Intramedullary spinal epidermoid cyst of the upper thoracic region.

We report a 40-year-old male who presented with a two year history of thoracic cord compression. MRI of the thoracic spine demonstrated a diffuse, non-gadolinium enhancing intramedullary spinal cord tumour, extending from the C7 to T2 vertebral body levels. The lesion was surgically resected and the pathology revealed an epidermoid cyst. Epidermoid cysts are rare slow-growing lesions apparently resulting from inclusion of ectodermal tissue during the closure of the neural tube. The average age of presentation is about 35 years and the history of the symptoms is usually long. The treatment is surgical, and complete removal is the goal, if possible.

Longitudinal study of MRS metabolites in Rasmussen encephalitis.

This study analyses the evolution of metabolite changes in an 8-year-old boy with focal Rasmussen encephalitis. Five MRI examinations, including magnetic resonance spectroscopy (MRS) were performed over 9 months. Following complex partial status, T2-weighted imaging showed transient dramatic signal increase in the left superior temporal gyrus and mesial temporal structures. Subsequent scans showed resolution of the swelling and signal normalization, with development of slight focal atrophy. MRS after status showed a reduction in N-acetylaspartate, total creatine and trimethylamines. Subsequent scans showed complete resolution of these metabolite abnormalities, followed later by development of further abnormal metabolite values. Lactate and glutamine/glutamate were elevated after status. After surgery, ex vivo high-field (1)H and (31)P MRS confirmed metabolite abnormalities (elevated choline and decreased aspartate, N-acetylaspartate, [(1)H]glutamate together with altered [(31)P]phospholipid ratios. These findings suggested active disease process in the anterior region of the excised superior temporal gyrus. We conclude that Rasmussen encephalitis is a combination of progressive encephalitic damage and fluctuating seizure effects, in which neuronal injury and recovery can occur. MRS measurements at a single time point should consider the fluctuating metabolite profile related to seizure activity.

Spontaneous haemorrhage into an empty sella turcica mimicking pituitary apoplexy.

We present a case of spontaneous haemorrhage into an empty sella turcica with the features of subclinical pituitary apoplexy. A 66-year-old woman with a previously resected pituitary adenoma presented four months later with progressive headache and visual deterioration. Cranial MRI demonstrated hyperacute blood products in a recurrent pituitary adenoma. Operative findings were of subacute blood in an empty sella turcica. There was no operative or subsequent histological evidence of tumour recurrence. The intrasellar haemorrhage was evacuated via a trans-sphenoidal approach, resulting in a rapid improvement in visual function. Endocrine deficits required thyroxine, corticosteroid and desmopressin supplementation. Haemorrhage into an empty sella turcica has not been previously described and needs to be suspected as a clinical entity in patients presenting with the features of pituitary apoplexy. Awareness of this clinical condition will prevent preoperative misdiagnosis.

Intraoperative monitoring to preserve central visual fields during occipital corticectomy for epilepsy.

Photic driving using a flashing strobe light was recorded via intracranial electrodes in two patients with occipital epilepsy being evaluated for surgery. The same technique was used to monitor the visual cortex intraoperatively. Visual evoked potentials (VEPs) were also obtained using the intracranial electrodes in one patient. Preoperative photic driving occurred in a separate location from the cortical areas producing ictal epileptiform activity. VEPs were located in the same site as photic driving. Photic driving was monitored throughout the resection and remained unaffected at the end of each procedure. Postoperative visual field testing in both patients showed preservation of central vision although some reduction in peripheral fields was seen. Intraoperative monitoring of the visual cortex using photic stimulation proved to be a reliable technique for preserving central vision during occipital lobe surgery.

Motor cortex localization using functional MRI and transcranial magnetic stimulation.

OBJECTIVE: Congenital brain lesions producing focal seizures may be accompanied by reorganization of the areas responsible for motor and sensory functions within the brain due to a phenomenon that has been termed "neuronal plasticity." This can be studied using functional MRI (fMRI) and transcranial magnetic stimulation (TMS). Using either method, the motor cortex can be localized noninvasively, but to date there have been few studies correlating the level of agreement between the two techniques. METHODS: We used fMRI and TMS to localize the motor cortex in a young woman with intractable focal seizures, congenital left arm weakness, and a dysplastic right hemisphere on MRI. RESULTS: There was excellent agreement in the localization of motor representation for each hand. Both were predominantly located in the left hemisphere. fMRI also showed an area of posterior activation in the right hemisphere, but there was no evidence of descending corticospinal projections from this site using TMS, direct cortical stimulation, and Wada testing. CONCLUSIONS: Functional MRI (fMRI) and transcranial magnetic stimulation (TMS) were successfully used to localize cortical motor function before epilepsy surgery. Each technique demonstrated migration of motor function for the left hand to the left motor cortex. After resection of the dysplastic right precentral gyrus there was no permanent increase in weakness or disability. The two techniques are complementary; fMRI indicates all cortical areas activated by the motor task, whereas TMS identifies only those areas giving rise to corticospinal projections.

Presurgical evaluation of the motor hand area with functional MR imaging in patients with tumors and dysplastic lesions.

PURPOSE: To test an optimized functional magnetic resonance (MR) imaging procedure to depict the motor hand representation area (HRA) in patients with epilepsy lesions near the central sulcus. MATERIALS AND METHODS: Fast low-angle shot MR imaging was performed with an oblique single-section imaging technique in eight control subjects (10 hemispheres) and six patients (12 hemispheres). Three series of five activation images (obtained while subjects performed repetitive finger-to-thumb opposition movements) and five rest images were acquired. Each hemisphere was studied in three adjacent sections. Difference maps (obtained with simple subtraction between activation and rest images) were compared with t-test maps. RESULTS: In control subjects, the HRA was visible in 27 of 30 sections. Qualitatively, activation was seen better on t-test maps in 14 and on difference maps in four of these sections. In all patients, motor activation could be seen in the hemisphere that contained the lesion. This activation was considered normal in four patients. In two patients, the HRA was deformed. Functional MR imaging activation in the motor area was confirmed with Penfield stimulation in five patients. CONCLUSION: Functional MR imaging findings in the preoperative assessment of dysplastic lesions around the central sulcus are the same as for tumors. t-test maps are superior to difference maps in the treatment of motor functional MR imaging data.

Perfusion patterns during temporal lobe seizures: relationship to surgical outcome.

We sought to determine whether patterns of ictal hyperfusion demonstrated using [99mTC]HMPAO (hexamethylpropylene amine oxime) single photon emission computed tomography (SPECT) predict outcome of temporal lobectomy; in particular, whether the more extensive patterns of ictal hyperperfusion are associated with poor outcome. We studied 63 patients who had ictal SPECT studies prior to temporal lobectomy. Hyperperfusion on ictal SPECT scans was lateralized, and classified into: (i) 'typical', (ii) 'typical with posterior extension', (iii) 'bilateral' and (iv) 'atypical' patterns. Outcome (minimum of 2 years follow-up) was classified as either seizure free, or not seizure free. Actuarial analysis was used to test the relationship of SPECT patterns with outcome. There were 35 cases with the typical ictal SPECT pattern, 13 posterior, nine bilateral and six atypical cases. The atypical pattern was associated with lack of pathology in the surgical specimen. Outcome was similar for the typical, posterior and bilateral with 60%, 69% and 67% seizure free, respectively. In contrast, the atypical group had a worse outcome with only 33% seizure free. Actuarial analysis showed a significant difference in outcome between patients with the typical pattern, and patients with the atypical pattern (P = 0.04). We conclude that extended patterns of ictal perfusion in temporal lobe epilepsy do not predict poor outcome, indicating that extended hyperperfusion probably represents seizure propagation pathways rather than intrinsically epileptogenic tissue. Atypical patterns of hyperperfusion are associated with poor outcome and may indicate diffuse or extra-temporal epileptogenicity.

A new instrument for improved accuracy of stereotactic depth electrode placement. Technical note.

A disadvantage of stereotactic placement of flexible depth electrodes is the risk of inaccurate positioning as a result of electrode movement when the introducer is withdrawn. A simple device that virtually eliminates this error is described.

Preoperative MRI predicts outcome of temporal lobectomy: an actuarial analysis.

We used actuarial methods to study outcome after temporal lobectomy in 135 consecutive patients classified into subgroups according to preoperative MRI findings. Sixty months after surgery, 69% of patients with foreign tissue lesions, 50% with hippocampal sclerosis, and 21% with normal MRIs had no postoperative seizures. An eventual seizure-free state of 2 years or more, whether the patient was seizure-free since surgery or not, was achieved by 80% of patients with foreign tissue lesions, 62% of those with hippocampal sclerosis, and 36% of those with normal MRIs. Outcome was worse in those with normal MRIs than in the other two groups. Early postoperative seizures with later remission (the "running down" phenomenon) occurred in all groups. Late seizure recurrence was present only in the hippocampal sclerosis group. These data show that preoperative MRI is a useful predictor of outcome and that actuarial analysis provides insight into different longitudinal patterns of outcome in MRI subgroups. This information can now be used in preoperative counseling.

Temporal lobectomy for epilepsy - complicationsin 200 patients.

At the Austin Hospital, Melbourne, Australia, 200 consecutive temporal lobectomies were performed for refractorycomplex partial seizures between 1969 and 1991 as part of its Comprehensive Epilepsy Program. The complications of this retrospective series are reported. There were no 30-day postoperative deaths but there were 6 late deaths. Complications are divided into 'major' if permanent and/or severe or 'minor' if temporary or not severe. Complications included hemiparesis (2% major, 1% minor), visual field defect (3% major, 18. 5% minor), dysphasia (96 dominant resections - 0% major, 5. 5% minor), memory impairment (1 % major, 9. 5% minor); intracranial infection (2% major, 0% minor), and miscellaneous (11 % minor). The mechanisms of the complications are discussed. Temporal lobectomy for the treatment of epilepsy can be performed with a low morbidity.

Concurrent adjacent meningioma and astrocytoma: a report of three cases and review of the literature.

Three patients presenting with an adjacent meningioma and astrocytoma are described. A review of the literature discusses several modes of neuroimaging and the difficulties in diagnosing simultaneous adjacent tumors. Aspects of the pathology and etiology of these tumors are also reviewed.

Seizure outcome and pathological findings following temporal lobectomy in patients with complex partial seizures and foreign tissue lesions seen only on MRI.

11 patients with foreign tissue lesions (FTL) in the temporal lobe associated with complex partial seizures (CPS) were studied. All had lesions clearly definable on magnetic resonance imaging (MRI) but not seen on computerised tomographic (CT) scans. All cases showed seizure reduction following temporal lobectomy with 10 becoming seizure free. Pathology showed 9 tumours, 1 hamartoma and 1 cavernous angioma. Hippocampus was available for examination in 7 cases, showing abnormalities in 6. Our findings suggest MRI be mandatory in screening patients with CPS and that following surgery, outcome should be excellent.

Surgical damage stimulates proliferation of dopamine uptake sites in normal mouse brain.

To test the hypothesis that proliferation of host dopaminergic tissue in response to injury plays an important role in the response to intrastriatal grafting, we transplanted autologous adrenal medullary to striatum in normal C57-black mice and compared this procedure with transplantation of non-dopaminergic tissue (frontal cortex) or a non-cellular matrix (Gelfoam). [3H]Mazindol autoradiography revealed that all three protocols resulted in a marked proliferation of dopamine uptake sites 10 months after transplantation.

Craniotomy and thoracotomy for non-small cell carcinoma of the lung with cerebral metastasis.

Twenty patients with non-small cell carcinoma of the lung who had cerebral metastasis, were treated by craniotomy and thoracotomy. Eighteen of these patients had a solitary metastasis and all were treated as curable. Ten patients presented with synchronous lung and brain disease. Of the remaining 10, nine initially presented with the lung tumour, which was treated first. There was a zero operative mortality rate and median survival was 12 months with reasonable quality of life for this time.

Localised neuronal migration disorder and intractable epilepsy: a prenatal vascular aetiology.

Localised neuronal heterotopias are an increasingly recognised cause of intractable focal epilepsies. The aetiology of these circumscribed disorders of neuronal migration is often unknown although in some instances proximity to areas of prenatal infarction suggests that severe ischaemia was responsible. A patient is described with intractable complex partial seizures associated with heterotopic grey matter and cerebral hypoplasia confined to the territory of the left posterior cerebral artery; the left hippocampus was spared. Angiography showed a normal left anterior choroidal artery but a hypoplastic left posterior cerebral artery, implicating prenatal ischaemia without frank infarction as the aetiology of the malformation.

Evidence for plasticity of the dopaminergic system in parkinsonism.

A series of compensatory mechanisms within the dopaminergic system have been shown to maintain clinical function in the presence of dopamine loss. Experimental evidence for increased presynaptic dopamine turnover owing to increased dopamine synthesis, release, and reduced reuptake exists. Direct evidence that these mechanisms maintain extracellular dopamine levels is provided by intracerebral microdialysis techniques. Postsynaptic denervation supersensitivity clearly occurs with D2 dopamine receptors, although this is less evident with D1 receptors. Similarly, mechanisms of plasticity have been shown to be relevant in human postmortem and Positron Emission Tomographic studies of patients with Parkinson's disease. However, although presynaptic increases in dopamine turnover are well documented, postsynaptic D1 and D2 receptor changes have been more difficult to establish, mainly because of methodological difficulties. D2, but not D1, receptor increases have been documented in drug naive Parkinsonian patients with PET techniques. In transplantation of adrenal gland to striatum in animal models and patients with Parkinsonism where clinical improvement occurs, plasticity of host response may be as important as plasticity of the graft. Although some elements of the compensatory mechanism of dopamine plasticity may be deleterious, such as dyskinesias owing to dopamine receptor supersensitivity, the overall effect of delay and minimization of the clinical expression of disease is advantageous. An even greater understanding of the mechanisms involved may assist in developing future therapeutic strategies.

Hippocampal sclerosis can be reliably detected by magnetic resonance imaging.

Two independent blinded observers reported the preoperative MRIs in a series of 81 consecutive patients with intractable temporal lobe epilepsy who were undergoing temporal lobectomy. We then compared the nature and lateralization of the MRI abnormalities with the pathologic diagnosis and the side of lobectomy. The MRI criteria of hippocampal sclerosis were an increased T2-weighted signal and the signal's confinement to a unilaterally small hippocampus. Imaging was performed in coronal and axial planes, specially orientated along and perpendicular to the long axis of the hippocampal body. We found diagnostic MRI abnormalities in 25 of the 27 cases with pathologically proven hippocampal sclerosis (sensitivity 93%, specificity 86%). In addition, we detected all 13 foreign tissue lesions on MRI. Overall, we detected lateralized lesions on MRI that correctly predicted the side of the epileptogenic temporal lobe in 72 cases (89%), with 2 possible errors. A learning effect in appreciating the relatively subtle MRI changes of hippocampal sclerosis was apparent in our later cases, as shown by an improved correlation between the 2 observers. This study demonstrates that hippocampal sclerosis can be identified on MRI with a high degree of sensitivity and specificity.

Subarachnoid haemorrhage due to cauda equina haemangiopericytoma.

A case of cauda equina haemangiopericytoma presenting with spinal subarachnoid haemorrhage is reported. The tumour had been asymptomatic until 2 weeks prior to presentation, and resulted in complete paraplegia below L3. The authors underline the uncommon association of spinal subarachnoid haemorrhage and cauda equina tumour and the rare finding of a cauda equina haemangiopericytoma.

Blunt trauma to the carotid artery.

Non-penetrating trauma to the internal carotid artery presenting as an immediate or delayed neurological deficit is an uncommon clinical entity. It has a high reported morbidity and mortality. Three cases are presented with long-term clinical and radiological follow-up. The mechanisms of injury, clinical features and possible treatment modalities are discussed.