Lisa Countryman-Jones, BS, MT(ASCP) CLS, CPT(NCA), ACCE

• Faculty Member, Clinical Practice Coordinator
• Medical Laboratory Technology Program
• Portland Community College
• Portland, Oregon

The anterior and posterior transcortical and transcallosal approaches are suitable for access not only to the lateral ventricles but also to the third ventricle diabetes diet sample cheap precose 50mg free shipping. The following is a description of these approaches as used for accessing the lateral cavity diabetes service dogs generic precose 50mg otc. The specific aspects of third ventricular exposure with these approaches are discussed in Chapter 139 diabetes medications linked to pancreatic cancer precose 25 mg with amex. Either the cerebral hemisphere or the corpus callosum must be traversed to reach the ventricular cavity blood glucose before eating buy precose 25mg on-line. To minimize parenchymal traumatization by surgical manipulation, natural pathways such as the cerebral sulci, fissures, and cisterns should be used diabetes mellitus medical definition cheap 50mg precose mastercard. It was Yasargil and Abdulrauf who introduced this philosophic shift from transcerebral to transcisternal planning of surgical corridors diabetes symptoms numb lips safe 25mg precose. There are two generally accepted avenues to the lateral ventricle: the transcortical and interhemispheric pathways. The decision to approach transcortically or via an interhemispheric route depends on the location and size of the tumor and varies on a case-by-case basis. The standard position of the patient is supine with elevation and flexion of the head. For the craniotomy, two bur holes are drilled on the contralateral side close to the sagittal sinus. Mobilization of the draining veins is important for gaining space, and their sacrifice should be avoided. This strategy is preferred over the use of rigid retractors so as to protect neural structures from pressure and tearing damage. Entrance to and advance within the interhemispheric fissure are achieved by blunt dissection with tailed cotton strips and balls. When the corpus callosum is reached, an entrance of 10 to 15 mm is generally enough for removal of most lesions located in the frontal and middle parts of the lateral ventricles. The smoothest way of opening is to dissect along the plane of the fibers with fine-tipped bipolar forceps and small tailed cotton strips. For better orientation in the presence of large tumor masses with severely distorted ventricles, the surgeon will find the thalamostriate vein located on the right side of the plexus in the right lateral ventricle and on the left side of the plexus in the left lateral ventricle. The further course of the plexus and vein leads to the internal cerebral vein, which serves as a guide for localization of the fornix and thalamus and thus acts as an important landmark. Caution needs to be taken regarding the genu of the internal capsule, which reaches the surface of the ventricle lateral to the foramen of Monro where the thalamostriate vein turns medially toward the internal cerebral vein. Instead of entering toward the lateral ventricle by opening the middle frontal gyrus as described earlier, the superior frontal sulcus is chosen for creation of the corridor. The advantages and disadvantages are the same as described for the transcortical approach. The craniotomy is placed superior and inferior to the lambdoid suture, including the midline (as in the anterior interhemispheric approach), and can be varied according to the position of the superficial bridging veins. The posterior interhemispheric fissure is then opened widely to minimize retraction, and the precuneus and isthmus of the cingulate gyrus are opened to give access to the ventricle. Although this approach leads to direct access to the trigone, one should be aware that it poses a risk for possible neurological complications, such as visual field defects, apraxia, and acalculia. The Transsylvian Approach to the Temporal Horn the proximal transsylvian approach was developed by Yasargil in 1967 for the treatment of vascular and neoplastic lesions in the mesial temporal area. Through a pial incision lateral to the M1 segment of the middle cerebral artery between the origin of the anterior temporal and temporopolar arteries, one can gain access to the temporal horn. In particular, limbic tumors of the amygdala, hippocampus, and parahippocampal area extending into the temporal horn can be removed with this approach without injuring the adjacent neocortex of the superior, middle, and inferior temporal gyrus and lateral temporo-occipital gyrus. The Anterior Transcortical Approach this route provides excellent access to the frontal horns and bodies of the lateral cavities, and even the anterior part of the third ventricle can be exposed. This approach is most suitable for patients with large ventricles and for pathologies within the lateral frontal horn of the nondominant cerebral hemisphere. With the patient in the supine position and the head turned between 10 and 15 degrees to the opposite side, the skin incision and craniotomy are placed over the main part of the middle frontal gyrus. The advantage of the transcortical approach is that bridging veins are not a concern. The Occipitotemporal Sulcus Approach the occipitotemporal sulcus approach can be used to access lesions in the posterior part of the temporal horn. As is the case with other lateral transcortical approaches, there is a risk for postoperative visual field deficits. A, the patient was placed in the supine position, and a coronal skin incision has been marked behind the hairline. B, A small right-sided parasagittal craniotomy was performed that extended beyond the midline to completely expose the superior sagittal sinus. C, Tumor exposure was obtained via the interhemispheric transcallosal approach; both pericallosal arteries are kept medial by the suction tube, and a self-retaining brain retractor is inserted into the divided corpus callosum. The skin incision is bicoronal, usually at the level of or slightly behind the coronal suture. The craniotomy is generally performed on the right side but extends slightly to the contralateral side to completely expose the superior sagittal sinus. Small bur holes are placed obliquely in the skull at the margin of the craniotomy so that the dural flap (with its pedicle toward the sinus) can be sutured to the bone. This allows a straight-line view into the interhemispheric fissure directly at the level of the falx cerebri. We prefer wide dissection of the interhemispheric fissure in the anteroposterior direction. In many instances, this allows working in the depth of the lateral ventricle without the use of self-retaining retractors. Care is taken to penetrate the corpus callosum more laterally to avoid entrance into the ventricle on the wrong side of the septum pellucidum, which may be displaced by a large tumor. We use a probe of the ultrasonic aspirator that is sufficiently long and suitable for working in a deep and narrow surgical field. This complication can be avoided by subsequent rapid tumor debulking with the aid of the ultrasonic aspirator, particularly if the tumor has a high tendency to bleed during the initial stage of the resection. Clinical symptoms arise from obstructive hydrocephalus, which leads to intracranial hypertension. In addition, cognitive changes are seen frequently, especially memory and attention deficits. There were no postoperative neurological deficits; however, the patient needed placement of a ventriculoperitoneal shunt because of hydrocephalus. Although they most commonly arise within the fourth ventricle, they are located within the lateral ventricles in up to 40% of patients. Histologically, this tumor shows isomorphic nuclei in clustered patterns, a fibrillary matrix, and small cysts. Because of the benign natural history of these tumors, they remain clinically silent in many cases and are often detected only during autopsy studies. If clinical signs are absent, routine follow-up with imaging studies is recommended. If dynamic growth during follow-up or the development of clinical symptoms occurs, microsurgical removal of the mass is the treatment of choice. In patients with existing neurological deficits caused by the remnant mass, operative resection (or eventually radiotherapy) should be discussed. Typically, they are detected between the second and fourth decades of life, with equal distribution between the sexes. The presence of necrosis, cysts, and calcifications in these tumors sometimes causes a heterogeneous appearance. Initially, an external ventricular drain was placed to treat the occlusive hydrocephalus. E, the child was operated on in the supine position with the aid of intraoperative neuronavigation. The postoperative course was uneventful, and the young patient underwent chemotherapy. The tumor (a central neurocytoma) was totally removed via the interhemispheric transcallosal approach. Postoperatively, mutism was observed for several days but completely resolved within the first week after surgery. The patient has now been monitored for more than 12 years continuously and has shown an uneventful course. In most cases, central neurocytomas are slow growing and become clinically evident as a result of increased intracranial pressure from obstructive hydrocephalus that causes symptoms of headache, nausea, vomiting, gait disturbance, and cognitive deficits. Nevertheless, although central neurocytomas are generally considered to be benign, malignant courses with progression of remnant tumor and cerebral and spinal dissemination have been reported and associated with unfavorable clinical outcomes. Clusters, perivascular pseudopalisades, and calcification are typical histologic characteristics. On histopathologic examination, nuclear atypia is present, including enlarged, irregular hyperchromatic nuclei. This tumor shows diffuse and infiltrative growth; giant cell astrocytomas are found in patients suffering from tuberous sclerosis. This coexistence is well documented in the literature, and the neoplasm is typically located in the vicinity of the foramen of Monro and can extend to the cavity of the lateral ventricle. Cyst evacuation and tumor biopsy were performed immediately to release the intracranial pressure. The patient quickly recovered from this procedure, and no further therapy was necessary during the following period of pregnancy. The patient then underwent elective surgery via the posterior interhemispheric subcallosal approach, and the tumor was removed completely, with preservation of the involved fornices on both sides. If symptomatic lesions are diagnosed, surgical resection is the treatment of choice. With regard to incidental findings of ventricular gliomas, treatment is still controversial. In patients with small nonsymptomatic tumors, clinical follow-up with regular outpatient consultations and imaging studies is justified. High-grade gliomas of the lateral ventricle may frequently arise from the corpus callosum, the septum pellucidum, or the thalamus and show a predilection for the anterior horn of the lateral ventricle. There is a slight male preponderance, with a male-tofemale ratio that varies from 1. When anaplastic transformation is in progress, the nuclei vary in number, size, and shape. This tumor accounts for 12% to 15% of all intracranial tumors and shows astrocytic differentiation in 60% to 75% of cases. Histopathologic study reveals the typical malignant characteristics, such as nuclear atypia, cellular pleomorphism, a high mitotic rate, and necrosis. In particular, if the fornices have been invaded, biopsy is preferred instead of extensive surgery. When these lesions are located in the lateral ventricle, the median age at diagnosis is 18 months, and there is no predilection to occur in either sex. E and F, He underwent microsurgical resection of the tumor via the intraparietal sulcus approach with the aid of the BrainLab neuronavigation system. G and H, Gross-total removal of the lesion was documented on postoperative computed tomography scans. Initially, a metastatic tumor was suspected because the patient had previously suffered from renal carcinoma. E and F, the tumor was completely removed via a left parietal transsulcal/transcortical approach. Before surgery, the patient suffered from symptoms of raised intracranial pressure. They are similar in aspect to the glomus of the choroid plexus, being formed by a single cell layer of cuboid or cylindrical cells surrounded by a thin fibrovascular structure. In imaging studies, these tumors frequently contain calcifications, hemorrhagic elements, or cysts. In some cases, choroid plexus papillomas may fill the ventricular cavity, whereas in others, the ventricle may be markedly dilated ipsilaterally. It is helpful to expose and interrupt the proximal arterial supply from the choroidal artery to devascularize the tumor at an early stage of the procedure. At the end of the procedure, the remaining portions of the apparently healthy choroid plexus are resected as well to ensure complete tumor removal. Ventricular meningiomas account only for 1% to 5% of all ventricular tumors and are located within the atrium in most cases. The arterial supply stems from branches of the choroidal arteries, and they drain into the deep ventricular veins. Their histopathologic features and natural behavior are the same as those in any other location in the neural axis. In most cases, typical symptoms of elevated intracranial pressure do not occur, but rather, cognitive deficits affecting attention and memory dominate the clinical findings. Patients with these symptoms have a good prognosis overall after removal of the cause. F, After being placed in the right park bench position, he underwent surgery with the aid of the BrainLab neuronavigation system. G and H, Note the significant vascularization as shown by digital subtraction angiography. As a result of their location, these tumors can gain mass volume before causing neurological symptoms.

A speech disorder involving articulation, called dysarthria, can accompany tumors of the posterior fossa or cerebral hemisphere and is not unusual in meningeal carcinomatosis diabetes mellitus zuckerwerte buy precose in united states online. Subcortical tumors of the hemispheres frequently produce weakness of the contralateral body side diabetes insipidus nasal spray purchase 50mg precose fast delivery. Usually increased deep tendon reflexes and other evidence of increased tone are seen diabetes test fasting blood sugar purchase precose paypal. Posterior fossa tumors may produce long-tract signs with accompanying weakness and incoordination diabetes in dogs loss of eyesight best purchase for precose. Cerebellar tumors frequently produce incoordination, difficulty in walking, and dysmetria (uncoordinated rapid alternating movements or point-to-point testing diabetic diet food chart order cheapest precose. Sensory disturbances include paresthesias (tingling sensations), numbness, or altered sensation diabetes type 2 quinoa cheap precose 50mg online. Cortical (usually parietal lobe) disturbances include proprioception loss, sensory discrimination (two-point, graphesthesia), and astereognosis. Gait disorders may accompany weakness, incoordination, or sensory disturbances and include falling and ataxia. Ataxia may accompany tumors in the posterior fossa or, occasionally, in the frontal lobes (apractic gait). Anosmia may be associated with infrafrontal meningiomas, which can compress the olfactory or first cranial nerve. As noted previously, cerebral hemorrhage into a tumor (usually choriocarcinoma), testicular tumors, melanomas, glioblastomas, and, less frequently, other tumors may also be associated with subarachnoid hemorrhage. Skull tumors, especially metastatic, may be associated with subdural collections of tumor and subdural effusions; the patient may present as if a chronic subdural hematoma were present. Meningeal carcinomatosis is frequently associated with multifocal neurological signs and symptoms, including cerebral, cranial nerve, and spinal cord and nerve disturbances. Tumors of the cerebral hemispheres are characterized by progressive, focal neurological deficit, and commonly by generalized or focal convulsive seizures. In addition, all motor function requires sensory input, and extensive connections link the frontal lobes with the somesthetic regions of the parietal areas and thalamus, along with visual input from the occipital lobes and auditory input from the temporal lobes. The frontal lobes also have widespread connections to limbic areas of brain, through which emotional tone is controlled. The disorders associated with frontal lobe lesions include intellectual impairment, impairment of initiative and spontaneity, personality changes, and motor disturbances. The disturbances may be sufficiently serious that they may predict survival after treatment. If the dominant frontal lobe is involved, aphasia is common; this is generally expressive in type but can be mixed receptive and expressive. Impairment of Initiative and Spontaneity A common manifestation of intellectual impairment is the inability to initiate tasks. Patients lose interest in their surroundings, often staring blankly when asked to become involved in family or business activity. They remain in bed and may not dress, preferring to sit around the house, often wandering aimlessly or watching television without much involvement in the programs. When severe, the patient has the characteristics of akinetic mutism; although paralysis is not seen, immobility may last for days. By contrast, the patient may be irritated by being disturbed and may respond angrily and inappropriately. Personality Changes Two types of personality changes may accompany a frontal lobe lesion: apathetic and indifferent (pseudodepressed) and euphoric (pseudopsychopathic). Pseudopsychopathic patients vary from those whose humor becomes inappropriate, such as making silly jokes (witzelsucht), to those who exhibit socially unacceptable behavior, such as disrobing or urinating in public. Although these dramatic examples do occur, by far the most common personality change is one of disinterest, inattentiveness, impersistence, and sometimes drowsiness. Motor Disturbances Patients with frontal lobe tumors almost always develop motor problems. A contralateral hemiparesis is common, usually associated with hyperreflexia and an extensor plantar response (Babinski). Butterfly gliomas may be associated with a magnetic-like apractic gait in which balance is disturbed and the patient has difficulty initiating walking. A tumor of the medial surfaces of the frontal lobes may cause precipitate urination. Frontal Lobe Tumor the frontal lobes are thought to contain the "seat of the intellect," but the brain works as an integrated whole and requires extensive interneuronal connections among multiple regions for its cognitive functions. Seizures from lesions in the hippocampal gyrus may include odd, often unpleasant odors as part of the aura-so-called uncinate fits. Tumors involving the surface of the dominant temporal lobe produce mixed expressive and receptive aphasia or dysphasia, chiefly anomia. Cerebellopontine Angle Tumor Cerebellopontine angle tumors, particularly acoustic or vestibular schwannomas, impair function of the eighth cranial nerve and are characterized by unilateral hearing impairment, tinnitus, and sometimes vertigo. Pressure on the adjacent cranial nerves, brainstem, and cerebellum produces loss of corneal reflex, facial palsy and anesthesia, palatal weakness, signs of cerebellar dysfunction, and, rarely, contralateral hemiplegia or anesthesia. Parietal Lobe Tumor Parietal lobe tumors may provoke either generalized convulsions or sensory focal seizures. Cutaneous tactile, pain, and temperature senses are intact, but stereognosis and the cortical sensory modalities (position sense, two-point discrimination) are impaired on the contralateral body side. Contralateral homonymous hemianopia (or inferior quadrantanopia), apraxia, and anosognosia (nonrecognition of bodily defects) may also be present. Speech disturbances, notably receptive aphasia or mixed expressive-receptive aphasia, agraphia, and finger agnosia, may occur when the tumor involves the dominant hemisphere. Pituitary and Suprasellar Tumor Pituitary and suprasellar tumors produce neurological and endocrinologic abnormalities. Pituitary adenomas may present as intrasellar secretory or nonsecretory masses, or masses with extrasellar extension. Enlarging pituitary adenomas cause headache; as the tumor grows out of the sella, it compresses the optic chiasm, nerve, or tracts, as well as the hypothalamus. The most common visual field defect is bitemporal hemianopia, but unilateral optic atrophy, contralateral hemianopia, or any combination of the three may occur. Hypothalamic compression usually causes diabetes insipidus from injury to the supraoptic-pituitary tract. The tumor may destroy functioning glandular tissue and cause pituitary deficiency. Occasionally, acute degeneration (hemorrhage or infarction) of a pituitary tumor produces pituitary apoplexy, the syndrome of sudden headache, amblyopia, diplopia, drowsiness, confusion, or coma. Associated convulsions may be preceded by an aura of flashing lights but not usually formed images. Subcortical Tumor Subcortical tumors commonly involve the internal capsule and produce contralateral hemiparesis or hemiplegia. They may invade any of the lobes of the hemisphere, producing corresponding symptoms. Thalamic invasion produces contralateral cutaneous sensory impairment and occasionally abnormal eye movements. Invasion of the basal ganglia usually does not produce parkinsonian symptoms, but athetosis, bizarre tremors, or dystonic postures occasionally occur. Cranial, extradural, or subdural metastatic tumors compress or, rarely, invade the underlying cortex and produce the same localizing signs as those caused by primary cortical tumor. Pineal Tumor Pineal tumors (usually germ cell tumors) occur at any age but are most common in childhood. Precocious puberty may result when a germinoma arises adjacent to the hypothalamus, especially in boys. The tumor compresses the aqueduct of Sylvius, causing hydrocephalus, papilledema, and other signs of increased intracranial pressure. Brainstem Glioma the functions of the brainstem are myriad, and their description is beyond the scope of this chapter. However, it is important to appreciate that dysfunction of the ascending sensory, descending motor, and intervening cerebellar pathways can produce a variety of neurological signs, along with focal dysfunction of cranial nerves and autonomic nuclei. Tumors of the brainstem are usually infiltrating astrocytomas, which do not obstruct the fourth ventricle. Symptoms of brainstem gliomas result from destruction of nuclear masses or unilateral or bilateral paralysis of the 5th, 6th, 7th, and 10th cranial nerves and paralysis of lateral gaze. Damage to the motor or sensory pathways causes hemiplegia, hemianesthesia, or cerebellar disturbance (ataxia, nystagmus, intention tremor). Optic Nerve Glioma Optic nerve gliomas may develop in the intraorbital, retroorbital, or chiasmatic region of the optic nerves, the first being most common. These tumors usually occur in early childhood, more often in girls, and produce uniocular loss of vision as the most common presenting symptom. It may be associated with small cell lung cancer, ovarian or uterine cancer, and lymphomas. The anti-Yo antibody reacts with two antigens that are found in the Purkinje cells and in the tumors. Treatment directed at the cerebellar disorder is ineffective, and successful treatment of the cancer does not improve the neurological disorder. Limbic Encephalitis and Encephalomyelitis Limbic encephalitis is an inflammatory process mostly confined to the limbic system; it is a rare complication of cancer, most commonly small cell lung cancer. The disease may include other areas of the brain (brainstem encephalitis) and spinal cord. Anti-Hu antibody may be identified, and as noted later, a sensory neuronopathy may also occur. Treatment of tumor may be associated with improvement in the neurological disorder. However, the disorder also occurs in the absence of tumor and may respond to immunologic therapies. Specific antigens have been identified for some of the antibodies, and for some, the gene defect has also been determined. Paraneoplastic neurological disorders are rare diseases, although their identification depends on the vigor with which a diagnosis is pursued. The associated cancers are often small at the onset of the neurological disorder and span the range of the common tumors, including small cell lung cancer, ovarian and breast cancer, and the lymphomas. However, within each category of cancer, the incidence of paraneoplastic disorder is still rare, especially for the specific disorders, such as paraneoplastic cerebellar degeneration. The incidence rises if one considers the nonspecific disorders such as sensorimotor peripheral neuropathy, which may accompany the cachexia of advanced cancer. This review concentrates on the specific paraneoplastic disorders, especially of the brain. Also included are functional impairment of the neuromuscular junction (Lambert-Eaton myasthenic syndrome), sensory neuronopathy, and the inflammatory myopathies. The combination of sensory neuronopathy and encephalomyelitis in patients with small cell lung cancer has been described in association with the presence of anti-Hu antibody (see Table 108-6). Opsoclonus and Myoclonus Opsoclonus consists of arrhythmic, multidirectional, high-amplitude conjugate saccades and is often associated with diffuse or focal myoclonus and truncal titubation, with or without other cerebellar signs. The syndrome occurs rarely in adults, of which some are paraneoplastic, usually associated with lung cancer. Polymyositis and Dermatomyositis Of the inflammatory myopathies, dermatomyositis, polymyositis, and inclusion body myositis, only the first is considered a paraneoplastic disorder, with an associated risk for cancer in up to 22% of patients. The myopathy involves proximal weakness, more in the legs than arms; the muscles may be painful and mildly tender. The serum creatine kinase is elevated up to 10 times the normal value, and the electromyogram demonstrates findings of myopathy. The rash of dermatomyositis is most commonly diffusely erythematous over the chest and shoulders in a V-shaped distribution. A minority of patients also have a red-violet heliotrope rash over the upper eyelids. Lambert-Eaton Myasthenic Syndrome Lambert-Eaton myasthenic syndrome is the most common of the paraneoplastic disorders, with an incidence of up to 6% in patients with small cell lung cancer. It differs from myasthenia gravis in that the pathogenesis involves reduced release of acetylcholine from presynaptic terminals rather than reduced postsynaptic receptor numbers. The bulbar muscles are not usually involved as they are in myasthenia gravis, and in fact power may actually increase with effort. Electromyography reveals a decrement of the compound muscle action potentials after low-frequency repetitive nerve stimulation and an increment after high-frequency stimulation. Patients usually present with proximal leg weakness, impotence in men, and dry mouth with a metallic taste in both men and women. Symptoms may improve after plasmapheresis or immunosuppression, supporting the notion that the illness is humorally mediated. Treatments that increase transmitter release may also improve the weakness; 3,4-diaminopyridine appears to be particularly effective. Clinical outcome in adult onset idiopathic or paraneoplastic opsoclonus-myoclonus. Quality of life self-reports from 200 brain tumor patients: comparisons with Karnofsky performance scores. Cognitive function as a predictor of survival in patients with recurrent malignant glioma. The Karnofsky performance status scale: an examination of its reliability and validity in a research setting. Vascular endothelial growth factor/ vascular permeability factor enhances vascular permeability via nitric oxide and prostacyclin. Cerebral vasodilatation causing acute intracranial hypertension: a method for noninvasive assessment. Vascular endothelial growth/permeability factor expression in human glioma specimens: correlation with vasogenic brain edema and tumor-associated cysts.

Craniotomy Technique the incision starts at the zygoma, anterior to the tragus, and is carried to approximately 2 to 3 cm above and encircling the ear, where it descends behind the mastoid process diabetic watch discount 50mg precose. The temporalis fascia is reflected sharply and is kept in continuity with the sternocleidomastoid muscle; the temporalis muscle itself is subsequently sharply dissected off the bone and reflected anteriorly and inferiorly blood glucose homeostasis diagram order cheap precose on-line. The first bur hole is placed just medial and inferior to the asterion, which is located at the inferior junction of the transverse and sigmoid sinuses diabetes symptoms leg numbness cheap precose american express. The second bur hole is placed at the squamous and mastoid junction of the temporal bone, along the projection of the superior temporal line, which opens into the supratentorial compartment managing diabetes pill cheap precose 25 mg with visa. The final two holes are placed approximately 2 to 3 cm more medially and closer together on either side of the transverse sinus diabetes patch generic precose 25mg amex. A temporoparietal craniotomy and lateral occipital craniotomy are performed without connecting the bur holes across the sinus diabetes type 2 natural treatment buy 50 mg precose with amex. After meticulous separation of the wall of the sinus from the flap, the bone plate is elevated. This stage of the operation requires familiarity with the anatomy of the temporal bone and its surrounding structures. The diamond bit should be used when drilling near vital neural and otologic structures. The surgeon next drills the superficial mastoid air cells and the deep (retrofacial) air cells. The facial canal and the lateral and posterior semicircular canals are identified. The dura at the floor of temporal fossa is also opened to the drainage point of the superior petrosal sinus. The head and neck are kept in a neutral position to maintain the anatomic course of the vertebral artery and for easier stabilization, if necessary. The ipsilateral shoulder is gradually pulled downward and taped to keep it from obstructing the field. Craniotomy Technique the skin is incised behind the ear in a curvilinear fashion two fingerbreadths behind the mastoid. The curved incision begins at the level of the external auditory canal and turns downward to the level of the C4 vertebra, where it gradually curves anteriorly into the horizontal neck crease. This skin flap is well vascularized and can easily be tailored to accommodate other approaches if necessary. First, the sternocleidomastoid muscle is detached from its origin at the occipital bone. Its innervation by the accessory nerve should be preserved and freed as it enters the medial aspect of the muscle at the level of the C3 vertebra. The splenius capitis, longissimus capitis, and semispinalis muscles-the muscles of the second muscular layer- are also detached along with the sternocleidomastoid muscle and retracted inferiorly and medially. The muscles of the third, deep layer create two triangles: the superior and inferior suboccipital triangles. The superior suboccipital triangle is delineated by the rectus capitis posterior major, obliquus capitis superior, and obliquus capitis inferior muscles. In the depth of this triangle is the venous compartment, which cushions the horizontal part of the suboccipital vertebral artery, its branches, and the C1 nerve. The inferior suboccipital triangle is delineated by the obliquus capitis inferior, semispinalis cervicis, and longissimus cervicis muscles. In the depth of this triangle is the vertical part of the suboccipital vertebral artery, its branches, its surrounding venous plexus, and the C2 nerve with its anterior and posterior rami. To improve exposure, the posterior belly of the digastric muscle can also be detached and reflected laterally. During surgery on foramen magnum meningiomas, two segments of the vertebral artery are encountered: the suboccipital (V3) and the intracranial (V4). Exposing and mobilizing the V3 complex allows full proximal control of the artery. Transposing the V3 complex allows drilling of the condyle, ventral exposure of the tumor, and safe dissection. This dissection spares the lateral (periosteal) ring, which is used to manipulate the V3 complex. The fibrous membrane around the sinus along with the areolar tissue on it must be kept intact to prevent bleeding and the possibility of an air embolus. The sigmoid sinus and jugular bulb are fully exposed, and the atlantal and occipital condyles are drilled. The dural incision is centered on the dural ring surrounding the vertebral artery. This incision extends further inferiorly and laterally to the level of the atlas or lower if necessary. Closure and Reconstruction Skull base approaches require especially meticulous closure. Vascularized pericranial graft provides the principal protective layer for skull base reconstruction. A vascularized temporalis muscle graft can also provide an additional strong reconstructive element for the larger, temporally based approaches. Microplating systems have enhanced the cosmetic results, especially in the zygomatic and maxillary areas. Malignant progression in meningioma: documentation of a series and analysis of cytogenetic findings. Radiation-induced meningiomas: clinical, pathological, cytokinetic, and cytogenetic characteristics. Significance of proliferating cell nuclear antigen in predicting recurrence of intracranial meningioma. Meningiomas: Their Classification, Regional Behaviour, Life History, and Surgical End Results. Four subtypes of petroclival meningiomas: differences in symptoms and operative findings using the anterior transpetrosal approach. Ki-67 immunoreactivity in meningiomas-determination of the proliferative potential of meningiomas using the monoclonal antibody Ki-67. Petroclival meningioms: multimodality treatment and outcomes at long-term follow-up. Functional outcome of patients with benign meningiomas treated by 3D conformal irradiation with a combination of photons and protons. Hyperostosis associated with meningioma of the cranial base: secondary changes or tumor invasion. Progesterone and estrogen receptors: opposing prognostic indicators in meningioma. A role for telomeric and centromeric instability in the progression of chromosome aberrations in meningioma patients. Meningioma radiosurgery: tumor control, outcomes, and complications among 190 consecutive patients. Ewend Meningeal sarcoma and hemangiopericytoma are two disparate entities that have several things in common, including being a mimic for their more benign counterpart meningioma. Diagnosis of either lesion should lead to an exhaustive systemic work-up because they are uncommon as primary intracranial lesions. Meningeal sarcoma and hemangiopericytoma do not have a unique constellation of symptoms but rather produce symptoms based on their intracranial location. This chapter reviews the history, pathology, clinical significance, and typical treatment paradigms for meningeal sarcoma and meningeal hemangiopericytoma. Nonmalignant tumors that may simulate sarcoma because of pleomorphism (pleomorphic xanthoastrocytoma, benign fibrous histiocytoma) or fascicular arrangement of the spindle cells with marked desmoplasia (superficial cerebral astrocytoma, desmoplastic infantile ganglioglioma) Lesions in the last group are not true sarcomas but do share some common histologic findings. Gliosarcoma is classified as a subtype of glioblastoma, an astrocytic tumor of neuroepithelial origin. Sarcomatous metastases are similar in clinical behavior to other brain metastases and are discussed elsewhere. Meningeal sarcomatosis, or diffuse infiltration of the dura by sarcomatous cells in the absence of a clear mass, also tends to occur in very young children. With the exception of rhabdomyosarcomas, which reportedly occur more frequently in the posterior fossa11 and in the midline,12 sarcomas occur with equal likelihood throughout the cranium. Sarcoma is derived from the Greek word sar, which denotes a fleshy character related to the gross appearance of these tumors. Median survival for these three subtypes is quite different: fibrous, 74 months; spindle cell, 27 months; and polymorphocellular, less than 1 year. The nervous system has multiple tissues of mesenchymal origin and thus may serve as the origin for sarcomas: dura, pia-arachnoid, stroma of the choroid plexus, adventitial fibroblasts associated with blood vessels, and tela choroidea. One can classify intracranial sarcomatous lesions into seven distinct groups7,8: 1. Brain invasion is frequently seen with these lesions despite a circumscribed radiographic appearance. Some of these tumors exhibit a lower grade of malignancy than other sarcomas, but local recurrence and local aggressive behavior are still seen frequently. Mesenchymal chondrosarcomas exhibit a pattern of pale staining and atypical chondroid areas alternating with compact cellular aggregates. These sarcomas have a moderate tendency to recur locally9 and may metastasize distantly. They occur more frequently in children, often in the posterior fossa,7,11,13 where they can be difficult to differentiate from medullomyoblastoma. Rhabdomyosarcoma can also be seen as part of germ cell tumors of the pineal and suprasellar region. The diagnosis is aided by immunohistochemistry for myoglobin, myosin, muscle-specific actin, and desmin. These tumors arise from the dura or leptomeningeal infolds and can extend along the Virchow-Robin spaces. Thus, a careful search for another primary site should be made if the diagnosis of intracranial fibrosarcoma is entertained. Given the higher frequency of gliosarcoma than fibrosarcoma, careful staining of the specimen with glial fibrillary acidic protein should be performed to exclude a glial component and the diagnosis of gliosarcoma. Burger and Scheithauer identified the following as useful methods for making that distinction. Those arising from the dura are often firm, whereas those arising without clear dural attachment are often softer. In contrast to gliomas, sarcomas tend to be more distinct, with clearer macroscopic borders between the tumor and surrounding brain. Recent evidence has classified these tumors as central and peripheral primitive neuroectodermal tumors, but they are still classified as mesenchymal tumors in the 2007 classification. Sarcoma develops in some patients after radiotherapy for a brain tumor26 and has developed in at least one patient after chemotherapy for a brain tumor. Sarcomas have been reported most frequently after irradiation of the sella for pituitary adenoma. Clinical symptoms include headaches, seizures, weakness, mental status changes, or symptoms of hydrocephalus (Table 132-2). Patients seen in this fashion are usually stabilized with therapy for increased intracranial pressure, such as steroids. If the tumor erodes through the skull into the soft tissues of the scalp, it may be manifested as a palpable mass. The presence of bone erosion overlying the mass suggests a more malignant tumor, but this finding may also be seen with typical and atypical meningioma. Underlying edema is also nearly universal with sarcomas but may also be seen in up to 50% of typical meningiomas. Invasion of the superficial venous structures may occur with both types of tumors. A coronal, contrast-enhanced, T1-weighted magnetic resonance image shows a large and homogeneously enhancing mass in the left temporoparietal region. The mass does not invade the skull; it displaces the cortex inwardly but does not invade it radiographically. Third, a past history of meningioma aids in the diagnosis, as does the presence of whorls or psammoma bodies. Malignant Fibrous Histiocytoma this rare intracranial tumor is histologically similar to its extracranial counterpart. Histologic findings include high cellularity, nuclear polymorphism, and varying inflammation. These tumors arise from the meninges and are within the differential diagnosis for dural-based lesions. The tumors are hypointense or isointense to brain tissue on unenhanced T1-weighted images. On T2-weighted Other Sarcomas Primary meningeal sarcomatosis refers to diffuse spread of sarcomatous tissue throughout the meninges without a focal mass. The tumor in the subarachnoid space covers the surface of the brain and may grow along penetrating vessels into the brain, as well as into the spinal and cranial nerves. A coronal, contrast-enhanced, T1-weighted magnetic resonance image shows a large mass in the right temporoparietal region. An axial, contrast-enhanced, computed tomographic scan shows a large enhancing mass in the right frontal region. It is an extra-axial mass with a large intracranial component that also extends through the skull into the overlying scalp.

In recent years, the overall incidence of papilledema in patients with brain tumor has decreased; currently, fewer than 20% of such patients have papilledema, although it is more common with increased intracranial pressure diabetes mellitus hyperkalemia generic 50mg precose mastercard. A jacksonian seizure is most likely to occur with central-parietal tumors, whereas partial complex (psychomotor) seizures are usually associated with temporal lobe tumors diabetes insipidus urine sodium cheap 25mg precose mastercard. Alteration of vision implies involvement of the visual apparatus, including a problem in the eye itself, the occipital cortex, or the oculomotor nerves diabetes insipidus causes discount precose line. Visual loss may involve reduced visual acuity, the occurrence of field defects, or diplopia signs of diabetic ketoacidosis purchase cheap precose on-line. Parietal lesions and temporal lobe lesions produce corresponding, variably congruent homonymous quadrantanopia diabete quebec recette precose 50 mg without a prescription. Pupillary abnormalities and oculomotor abnormalities may be caused by tumors growing in the base of the brain and involving the third cranial nerve, fourth nerve, or sixth nerve diabetes symptoms pee precose 50 mg mastercard. As noted previously, a sixth nerve paresis may accompany mass lesions as a false localizing sign. Hearing impairment may mean reduced auditory acuity or the occurrence of tinnitus and may be associated with vertigo. Hearing impairment is especially common in tumors that involve the eighth cranial nerve but may also accompany meningeal carcinomatosis and tumors of the fifth cranial nerve. Speech disturbances include impaired spoken language and understanding speech and may be transient or progressive; expressive and receptive dysphasia progressing to aphasia occurs. Generally, tumors involving the dominant posterior-inferior frontal lobe produce an expressive aphasia; those involving posterior parietal or posterior temporal lobe produce mixed receptive-expressive aphasia. In recent years, however, it has also become possible to localize the regions of likely maximal malignancy within the lesion as well as to depict with increasing accuracy the relationship of the lesion to surrounding structures. These efforts are typically undertaken to optimize the surgical path to the mass and to reduce or at least to predict surgically related morbidity. The fundamentals of lesion localization have not changed very much over the years, although the tools for doing so have made the task easier. The fundamental determination to be made remains whether the lesion is within the brain parenchyma or is extra-axial. In the case of many tumors, catheter angiography would demonstrate a tumor blush, indicative of an abnormally enlarged blood pool. The reduced concentration of deoxyhemoglobin and concomitant prolongation of T2* leads to a regional taskrelated increase in signal. In most cases, the experiments are set up in a so-called block design, in which epochs or blocks of task. These techniques are based on the biophysical observation that water molecules within axons move in a relatively unconstrained manner longitudinally along the length of the axon, whereas those molecules can move only a short distance radially before they encounter either microtubules or the axonal membrane. This plot represents graphically what is known mathematically as the diffusion tensor. Conceptually, by assessing the directionality of water diffusivity in each small imaging voxel and then linking the measures of maximal diffusivity end to end, one can begin to discern the trajectories of white matter tracts as they run through the brain. Ongoing technical developments include improvements in tracking white matter bundles through edema surrounding tumors (and even through tumors) and in separating white matter tracts that closely approximate one another, or that cross one another within a group of voxels. The additions of advanced neuroimaging techniques notwithstanding, the first decision a neuroradiologist must make when evaluating an intracranial mass is whether the lesion is intraparenchymal or extra-axial. Contrast enhancement of cranial leptomeninges l Relative absence of vasogenic edema l nerves or the Although each of these findings may also be identified with lesions that are intracranial (especially infiltration of or reaction by the overlying bone and relative absence of vasogenic edema), a combination of these features would suggest an extra-axial process. Among the extra-axial processes, five are most common: meningioma, schwannoma, lymphoma, metastases, and granulomatous diseases (most notably sarcoidosis). Schwannomas occur in stereotypical locations associated with cranial nerves and rarely have dural tails of enhancing tissue arising from the margins of the lesion. Sarcoidosis may affect the pia, dura, or parenchyma and will commonly have pulmonary manifestations. It may elicit more of a parenchymal inflammatory and edematous reaction than the other diagnoses. Other granulomatous diseases such as tuberculosis or fungal infection are differentiated based on systemic symptoms. In the end, meningiomas still predominate in the extra-axial compartment, and unless there are unusual features as described previously, this is the most likely diagnosis to consider. Particularly with a dural tail and fine calcification or bony reaction, meningioma is the top choice. These caveats aside, the presence of necrosis, edema, and calcification and the location are the main factors that suggest a specific histologic classification. Except for the center of the mass, much of it exhibits T2-weighted signal close to that of the surrounding brain. The latter is usually much more irregular and elicits more edema in the surrounding tissue. The lesions with the greatest degree of edema are the lymphomas, glioblastomas, and metastases. Calcification occurs frequently with oligodendrogliomas, neurocytomas, and craniopharyngiomas. Nonetheless, by virtue of their higher incidence, astrocytomas still represent the most common calcified tumor. The calcification of an oligodendroglioma tends to be coarser than the more stippled calcification of astrocytomas. The metastases that calcify include mucinous adenocarcinomas, osteosarcomas, and chondrosarcomas. Lesions that cross the corpus callosum are usually high-grade astrocytomas or lymphoma. Clearly, the differential diagnosis of a pineal region mass differs from one in the suprasellar region (although germinomas and meningiomas may break that rule) or one that is in the ventricle. This initial review offers insight into the framework that is used to diagnose most intracranial masses, with the understanding that radiology rarely preempts a histologic specimen, particularly for the intra-axial masses. It should be noted, however, that there is a wide variety of signal intensity characteristics associated with meningiomas, and in fact, some reports suggest that syncytial, transitional, and angioimmunoblastic meningiomas may have differing signal intensity characteristics depending on their internal histology. Meningiomas also have a characteristic "dural tail," which represents contrast enhancement extending along the margins of the tumor affecting the pachymeninges. Some histologic studies have suggested that the entirety of the dural tail represents meningioma tumor, whereas others have suggested that this may represent reactive change adjacent to neoplasm. Although these areas usually represent a reaction by osteoblasts to the tumor, in some cases the meningioma may permeate the bone. Alanine has been suggested to be a specific marker for meningiomas, but its presence is variable. Meningiomas may deviate from the characteristic benign appearance in many different ways and on occasion demonstrate necrosis, fatty degeneration, cystic areas, infiltration into the brain, infiltration into the bone, and marked vasogenic edema. Nonetheless, branches of the tentorial artery from petrous carotid meningeal branches may be responsible for the primary supply of tentorial meningiomas. Similarly, meningiomas around the cavernous sinus may have direct carotid branches supplying the lesion. Meningiomas at the foramen magnum may receive blood supply from branches of the vertebral artery or posterior inferior cerebellar artery. Schwannoma the next most common extra-axial mass is the schwannoma, dominated by those that occur in and around the internal auditory canal. This lesion characteristically resides in the cerebellopontine angle or in the internal auditory canal, arising most often from the vestibular branches of the 8th cranial nerve. Its imaging characteristics are similar to those of a meningioma from the standpoint of being relatively isointense to gray matter, but the absence of a dural tail usually helps to distinguish these two lesions. Vestibular schwannomas, however, may show cystic degeneration as well as hemorrhage and occasionally cause edema in adjacent brain tissue. As opposed to meningiomas, it would be highly unusual for an acoustic schwannoma to cause bony lysis or bony sclerosis. In particular, if a cerebellopontine angle lesion shows enhancing tumor entering the internal auditory canal, one would favor vestibular schwannoma over meningioma. Schwannomas of other cranial nerves, particularly of either the 7th or the 5th cranial nerve, are the next most likely extraaxial masses to arise from the cerebellopontine angle region or from the lateral pons. They have imaging characteristics similar to those of vestibular schwannomas, but they may be distinguished by virtue of their location and plane of growth. This lesion, which has extendedextracranially(black arrow),aswellasintracranially,demonstratesa"duraltail"(white arrows)thatextendsdownovertheright hemisphericconvexity. On dynamic imaging with contrast agents, the meningiomas show slow uptake of the contrast agent in a continuous fashion followed by a lengthy period of stable enhancement and a delayed clearance of the contrast agent. Some branches of the 5th cranial nerve may show contrast enhancement within the cavernous sinus or the pterygopalatine fossa. The 7th cranial nerve schwannomas may occur in the cerebellopontine angle cistern, the internal auditory canal, or the temporal bone. Schwannomas of the 9th, 10th, and 11th cranial nerves are rarely seen in the intracranial compartment, but when they occur, they usually erode portions of the jugular foramen. Ninth cranial nerve schwannomas, in particular, present more frequently in the intracranial compartment than in the head and neck region. Schwannomas of the 3rd, 4th, and 6th cranial nerves may present in the basal cisterns or within the cavernous sinus. In the cavernous sinus, these are difficult to distinguish from cavernous sinus meningiomas. Epidermoid Epidermoid tumors may arise in the cerebellopontine angle, the suprasellar cistern, the diploic space, the peripineal region, or the middle cranial fossa. Epidermoid lesions tend to have a crenated margin and will infiltrate adjacent structures, particularly along the brainstem. In this location, they must be distinguished from atrophy-related dilation of the subarachnoid space. Additionally, arachnoid cysts may remodel and thin the bone, which would not be seen with atrophy and subarachnoid space dilation (in fact, the bone may become thicker in younger subjects). One may see pulsation artifacts within an arachnoid cyst, which are not seen in an epidermoid tumor. Teratomas, choriocarcinomas, endodermal sinus tumors, and embryonal cell tumors are also among the germ cell line tumors occurring around the pineal gland. Choriocarcinomas have a high rate of hemorrhage, both in primary sites and in metastatic deposits. Pineoblastomas are sometimes placed in the classification of primitive neuroectodermal tumors. This low signal intensity on T2-weighted imaging probably reflects some combination of hypercellularity and calcification. Subarachnoid seeding may occur with pineoblastomas but is uncommon with pineocytomas, which take a less malignant course. Pineocytomas may have cystic components and may appear like a complex benign congenital pineal cyst. Sometimes, the tumoral tissue surrounds the normal pineal gland, resulting in an engulfed appearance to the calcification. Cystic change occurs in 33% of pineal region, 28% of suprasellar, and 80% of basal ganglionic germinomas. Response to radiation therapy may be dramatic, with scans showing no evidence of tumor within 2 weeks after completion of radiation therapy. The presence of cystic change portends a worse response to radiation SellarLesions Pituitary adenomas are tumors that arise in the sella and are typified by their characteristic location within or engulfing the pituitary gland. Although microadenomas (<10 mm) may not show bony abnormalities and may present purely as an intrapituitary area of abnormal density or intensity, a pituitary macroadenoma usually depresses the floor of the sella or extends upward into the suprasellar cistern. On administration of gadolinium, most pituitary microadenomas show decreased enhancement amid the highly enhancing pituitary gland. When evaluating a patient for a pituitary adenoma, one should always examine the optic apparatus to determine whether it is compressed by the tumor. Invasion of the cavernous sinus may be associated with higher hormonal levels and a more difficult surgical approach. Tumors that project laterally to a vertically oriented line bisecting the two turns of the ipsilateral cavernous carotid artery are likely to have invaded the cavernous sinus. In the parasellar region, pituitary adenomas may encircle the internal carotid arteries. They are distinguished from meningiomas that do the same by the fact that pituitary adenomas, because they are relatively soft, generally do not decrease the size of the lumen of the vessel, whereas meningiomas often narrow the carotid artery. The most common suprasellar lesion is extension of a large pituitary macroadenoma out of the sella through the diaphragma sella. Craniopharyngiomas often have cystic degeneration or calcification (with a higher rate in the adult population than in the younger age group). This may be due to the high protein content associated with the cyst or to hemorrhage. It is also important to consider the possibility of a cavernous carotid artery aneurysm, especially if the lesion is eccentric or exhibits the signal characteristics suggestive of turbulent flow. Phaserelated ghosting artifact, signifying flow, may be a helpful subtle finding to that end. These lesions are highly vascular, and one can see flow voids or calcifications as low signal intensity areas within the lesions. The two have similar imaging characteristics, but meningiomas usually occur in elderly patients and usually have more homogeneous signal intensity. In the differential diagnosis of lesions around the glomus of the lateral ventricle, one should also consider metastases, and rarely lymphoma and astrocytoma. Ependymomas may grow through the exits of the ventricle, a feature that is unusual for medulloblastomas. From the posterior fossa, the tumor may grow into the cerebellopontine angle cisterns, the cisterna magna, or the foramen magnum to get to the cervical region. When ependymomas arise in the supratentorial compartment, they may appear in the peripheral parenchyma unassociated with the ventricular system.

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