Magnetic stimulation of the spine: the role of tissues and their modelling.

Numerical modelling of magnetic stimulation in the spine is a scarce subject in the literature, although it has been gaining clinical acceptance. In the present work we present the results from a simplified computational model of the spine. The results indicate that it is necessary to use a numerical technique for solving the problem, which takes into account tissue dispersion and both dielectric properties (conductivity and permittivity), since a difference of 14% in the induced electric fields was found when displacement currents were included. With respect to the role of tissues in stimulation efficiency, it was confirmed that water-rich tissues lead to a shielding effect of the spinal cord. However, this effect becomes smaller at the height of the intervertebral discs, resulting in an increase of the field inside the spine.

Primary extracerebral meningeal glioblastoma: clinical and pathological analysis.

Primary meningeal gliomas are uncommon tumors in the subarachnoid space, their primary characteristic being the absence of any obvious connection to the brain parenchyma. Rarely, they are quite malignant and assume a bulky, well circumscribed appearance rendering the differential diagnosis from other CNS neoplasms difficult. A 53-year-old man presented with a history of persistent headaches and left sided weakness. Magnetic resonance imaging revealed a temporoparietal mass attached to the dura that strongly resembled a meningioma. At surgery, the outer layer of the dura mater was intact and there was a clear brain-tumor interface without obvious pial disruption. Histological examination showed a biphasic pattern consisting of benign connective tissue intermingled with bundles of what seemed to be a glioblastoma. The mass demonstrated strong positivity for GFAP and the MIB labeling index focally exceeded 20%. The tumor was identified as a primary meningeal glioblastoma. The patient was disease-free for 42 months, after which he developed a recurrence for which he was re-operated. This time, the pathological findings of the tumor were those of a typical glioblastoma multiforme. We discuss the origin of the initial neoplasm and also the differential diagnosis that needs to include meningioma, aggressive glioblastoma infiltrating the dura and a recently recognized bimorphic CNS tumor: the desmoplastic glioblastoma.

Multifocal glioblastoma with remote cutaneous metastasis: a case report and review of the literature.

BACKGROUND: Remote extracranial mestastases of glioblastoma multiforme (GBM) are uncommon, while cutaneous seeding at a distance from the operative site appears to be even more unusual. CASE REPORT: A 63-year-old man presented with focal seizures and mental impairment. Computed tomography (CT) scan revealed a left frontoparietal mass. He underwent a gross total removal of the tumor. The tissue diagnosis was that of a GBM. Seven months later, the patient developed a left scapular subcutaneous mass. Fine-needle aspiration cytology (FNAC) was performed and the cytological findings disclosed again a GBM. One month later, after clinical deterioration, a repeat magnetic resonance imaging (MRI) scan was carried out which demonstrated two new distinct lesions in the opposite hemisphere, as in a multifocal GBM. Both lesions were biopsed under stereotactic guidance and the recurrence of GBM was confirmed. The patient died ten months after the primary diagnosis of the intracranial GBM. CONCLUSION: Improved diagnostic modalities and prolonged survival have increased the likelihood of detection of extracranial mestastases from GBM. This potential may be greater in multifocal GBM. FNA is a valuable method for the definite diagnosis of metastatic GBMs. Although several theories have been postulated, the route of remote cutaneous dissemination and the mechanism of multifocal recurrence remain to be elucidated.

Suprasellar and intrasellar paragangliomas.

Neoplasms of the sellar region are entities with a large differential diagnosis. Although paraganglionic cells have not been demonstrated in the pituitary or adjacent structures, the existence of sellar region paragangliomas is well-documented. To elucidate, in this area the nature of these unusual tumors is relatively difficult. Clinical history, physical examination, radiographic investigation as well as intraoperative gross observation are the same as those of sellar meningioma or pituitary adenoma. Immunohistochemistry, using neuroendocrine markers and electron microscopy are the two definitive diagnostic methods to differentiate among these entities. The clinical management, the possible pathogenesis of the tumor, the importance of immunohistochemistry in making the diagnosis and the clinical outcome of these patients are discussed.

A sphenoid en plaque meningioma aggravates exophthalmos in a patient with thyroid ophthalmopathy.

PURPOSE: To describe the rare case of a patient with thyroid ophthalmopathy whose unilateral aggravated exophthalmos was caused by the development of an ipsilateral sphenoid wing en plaque meningioma. METHODS: Case report. RESULTS: The ophthalmologic examination included visual acuity assessment, anterior segment examination, funduscopy, ocular motility examination, and exophthalmometry. Magnetic resonance imaging (MRI) of the brain and orbit revealed the existence of a sphenoid meningioma. Removal of the tumor through a pterional craniotomy was performed. The histologic examination showed that it was an en plaque meningioma. There were no postoperative complications and no recurrence of the tumor was revealed 24 months after the operation. CONCLUSIONS: Detailed ophthalmologic examination and MRI of the brain and orbit are necessary in every patient with deterioration of the exophthalmos even if the suggestive cause seems obvious.

Subdural empyema and cerebellar abscess due to chronic otitis media.

The infratentorial variety of the subdural empyema, with or without coexisting cerebellar abscess, is a rare clinical entity that carries a high mortality rate. We briefly describe the case of a 49-year-old man presented with severe debility, fever and an obviously neglected chronic otitis media. The patient had refused surgical treatment several months ago. After admission, his level of consciousness began to deteriorate, and the radiological studies showed infratentorial subdural suppuration extending into the right cerebellar hemisphere, along with chronic pyogenic infection of the middle ear and the mastoid process. Radical mastoidectomy was performed first, followed by extensive right posterior fossa craniectomy. The two subdural collections and the cerebellar abscess were successfully evacuated. Subsequently, he received post-operative antibiotic treatment for 6 weeks. At follow-up, 10 months after surgery, his neurological recovery was complete except for a minor residual cerebellar dysfunction on the right. This unusual case highlights that in patients presented with severe intracranial complications of chronic otitis media, early diagnosis and radical surgical intervention may be life saving.

Transsphenoidal extradural chiasmapexy in the management of the symptomatic primary empty sella syndrome.

When patients with the usually clinically silent primary empty sella syndrome become symptomatic through visual field defects or hormonal deficits the condition was frequently treated by a transsphenoidal intradural procedure with a risk of consecutive CSF leak or meningitis. We present 3 cases in which we performed a transsphenoidal extradural procedure packing the sella and sphenoid sinus with fat tissue and discuss the procedure and results.

Parkinsonism as a manifestation of brain tumor.

Neoplasm is an uncommon cause of the parkinsonian syndrome. We are presenting three cases of intracranial tumors whose major manifestations included parkinsonism. Surgical treatment resulted in control of the extrapyramidal symptoms in two of our patients. Because no curative treatment is available for the vast majority of parkinsonian patients, early detection of an underlying neoplasm may offer a most rewarding outcome. Unilaterality of the symptoms, overwhelming dementia, or suspicion of a mass should lead to the performance of computed tomography.

Augmentation of cerebral blood flow induced by hemodilution in stroke patients after superficial temporal-middle cerebral arterial bypass operation.

Experimental hemodilutional therapy has been shown to raise collateral perfusion to acutely ischemic brain regions distal to occluded internal carotid (ICA) and middle cerebral (MCA) arteries and to reduce infarct size. Superficial temporal (STA)-MCA anastomosis surgically establishes additional regional collateralization, and this bypass angiographically enlarges over time. Despite bypass patency verification by Doppler recording made at the edge of the craniectomy, the microsurgical STA-MCA anastomosis in 11 stroke patients did not produce early changes in cerebral perfusion parameters in the MCA territory of either hemisphere as determined by 133xenon inhalation. Therefore, hemodilution was initiated in an effort to increase cerebral perfusion during this marginal period when the STA was beginning to dilate progressively. Incremental venesections with equal intravenous volume replacement with 5% human serum albumin caused a significant lowering of the hematocrit from 40 +/- 1 to 33 +/- 1%. This isovolemic hemodilutional therapy resulted in significant mean regional cerebral blood flow (rCBF) elevations of 23 +/- 5% (SE) in the bypassed MCA territory and of 25 +/- 6% in the opposite MCA region. The mean gray flow (F1) in the involved and homologous MCA regions significantly increased 27 +/- 8% and 30 +/- 11%, respectively. Similarly, the initial slope index (ISI2) significantly rose by 17 +/- 5% in the bypassed MCA territory and by 18 +/- 6% in the homologous region. These data objectively support the premise that reductions in hematocrit without intravascular volume expansion augment cerebral blood flow, probably by reducing blood viscosity.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative EEG alterations after isovolemic-hemodilutional augmentation of cerebral perfusion in stroke patients.

Eleven patients with ischemic neurologic deficits in the middle cerebral arterial (MCA) territory and ipsilateral slowing on initial EEG underwent venesection and equal volume replacement with intravenous 5% human serum albumin. As the mean hematocrit was reduced by 19%, the mean cerebral blood flow (CBF) in the MCA territory of the affected and contralateral hemisphere determined by the 133Xenon inhalation technique increased 18 and 21%, respectively. Similarly, CBF in the contralateral occipital region increased 17%. The percentage total slow-wave EEG activity (fractional sum of theta and delta activity, 1.0 to 7.5 Hz) determined by fourier analysis was reduced significantly in the affected MCA territory and in the contralateral occipital region within 1 to 2 hours after isovolemic hemodilution. Using quantitative EEG analysis, rapid improvement in background EEG activity can be demonstrated following the diffuse elevation in CBF by hemodilution.

Carpal tunnel syndrome. Decompression using the Paine retinaculotome.

The presenting symptomatology and clinical findings of 464 patients with the carpal tunnel syndrome are reviewed. The results of decompression by section of the transverse carpal ligament are presented, with particular reference to the use of the Paine retinaculotome. Approximately 90% of patients achieved very satisfactory results and complications were minimal. The commonest reason for failure is incomplete division of the flexor retinaculum. The detailed procedure is presented.

Massive cerebellar infarction: "conservative" management.

Eleven patients with large cerebellar infarctions were admitted recently to our service. Eight of them showed evidence of hydrocephalus on the CT scan examination. Five were treated with controlled external ventricular drainage and six were managed conservatively. One death, most likely due to progressive brainstem infarction, occurred. The outcome was favorable in the other patients. It is suggested that prompt treatment of the acute obstructive hydrocephalus may obviate the need for posterior fossa decompression in patients with massive cerebellar infarction.