Biomedical subjects
Publications and source records attributed to G R Cosgrove.
The case is reported of a 28-year-old man with "ectopic" craniopharyngioma recurring in the epidural space 21 years after the original tumor was resected. Previously described cases of similar remote recurrences as well as some features of the biological behavior of craniopharyngioma are discussed. The rarity of this postoperative complication is addressed.
The clearly documented transaqueductal migration of a solitary intraventricular neurocysticercus cyst is described. The cyst was fortuitously demonstrated on magnetic resonance imaging during migration through the aqueduct. The radiological appearance and clinical significance of this condition are discussed.
Classic aphasiology has been challenged by studies that have employed cranial computed tomography to test predicted anatomic-behavioral correlations. We treated a patient who developed a classic Broca's aphasia but whose computed tomographic scan revealed damage to Wernicke's area, thus seeming to contradict the principles of traditional aphasiology. However, subsequent information obtained by magnetic resonance imaging, intracarotid amobarbital (Amytal) testing, and electrophysiologic studies, including cortical stimulation, demonstrated that the brain-behavior correlations in this patient can be understood in terms of the formulations of traditional aphasiology.
The accuracy with which electrical sources in the brain can be localized by using electroencephalograms measured on the scalp is not well known. In this study, tests of localization accuracy were performed by using implanted dipolar sources in the human brain. These dipoles are created by passing a weak (subthreshold) current through intracerebral electrodes implanted in the brains of epileptic patients for seizure monitoring. The locations of these dipoles are accurately known from roentgenographs. First, 16 electroencephalograms produced by these dipoles were recorded, then inverse solutions were calculated for the apparent sources of these electroencephalograms. Finally, the locations of the apparent sources were compared with the known locations of the implanted dipoles to determine localization error. The average localization error for a total of 28 dipoles in 3 subjects was 1.1 cm. These results indicate that good localization accuracy for focal sources in the brain can be provided by scalp electroencephalograms.
A 128-channel cable-telemetry EEG monitoring system has been developed for use on patients undergoing intensive neurodiagnostic monitoring with invasive intracranial electrodes. A unique head mounted preamplifier/multiplexor design allows continuous recording from any combination of intracerebral, subdural, epidural or surface electrodes. A computer is used to delay or buffer all 128 channels by 2 min or more. This computer is connected to a fileserver via a local area network and is used exclusively for data acquisition. Seizure files created by the activation of the seizure/event push button or detected by a second computer containing on-line seizure/spike detection algorithms are written directly on to the fileserver by the acquisition computer. The 128 channels of EEG recorded on the fileserver can then be remotely reviewed on a high resolution graphics terminal, printed out on a laser jet printer, archived or played out on paper, 16 channels at a time on any EEG machine. A time of day signal is also generated by the computer to permit time correlation with a continuous audio/video VCR unit which permits comparison of the EEG and clinical events. This system allows continuous EEG monitoring of extensive multichannel arrays not previously possible with conventional 16-, 32- or even 64-channel systems.
With increasing computerization, digitization and complexity of 64- to 128-channel long-term monitoring (LTM), new problems have arisen with data presentation. We describe customized software that allows for high resolution EEG output on a standard laser printer. This system can display from 1 to 128 channels of EEG on standard or legal size paper with freedom to alter both time and amplitude scales as desired. This technique is inexpensive and provides a high resolution rectilinear paper record of selected EEG events that is convenient for review and storage.
A case of circumferential leptomeningeal metastasis to the spinal cord from an intracranial glioblastoma multiforme (spinal meningeal gliomatosis) is presented. The clinical, radiographic, and pathological features are described. Spinal magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid accurately demonstrated the spread of disease when compared with autopsy findings. The value of spinal magnetic resonance imaging in patients with symptoms attributable to cerebrospinal fluid metastases is discussed.
The ability to evaluate the intensity of emotional facial expressions was investigated in patients undergoing the intracarotid sodium amytal procedure. It was found that when the hemisphere non-dominant for language (usually right) was anesthetized, the patients' ratings of the intensity of emotional expressions in photographs were lower than baseline ratings of these expressions. Such an effect was not seen with anesthetization of the hemisphere dominant for language (usually left). Ratings of shades of gray (which served as control stimuli) showed no such effect. The findings are interpreted in terms of a right hemisphere superiority in the perception and evaluation of emotional expression.
It is believed that the magnetoencephalogram (MEG) localizes an electrical source in the brain to within several millimeters and is therefore more accurate than electroencephalogram (EEG) localization, reported as 20 mm. To test this belief, the localization accuracy of the MEG and EEG were directly compared. The signal source was a dipole at a known location in the brain; this was made by passing a weak current pulse simulating a neural signal through depth electrodes already implanted in patients for seizure monitoring. First, MEGs and EEGs from this dipole were measured at 16 places on the head. Then, computations were performed on the MEG and EEG data separately to determine the apparent MEG and EEG source locations. Finally, these were compared with the actual source location to determine the MEG and EEG localization errors. Measurements were made of four dipoles in each of three patients. After MEGs with weak signals were discounted, the MEG average error of localization was found to be 8 mm, which was worse than expected. The average EEG error was 10 mm, which was better than expected. These results suggest that the MEG offers no significant advantage over the EEG in localizing a focal source. However, this does not diminish other uses of the MEG.
The authors describe a rare case of multiple peripheral aneurysms of the posterior inferior cerebellar artery found in association with a midline cerebellar arteriovenous malformation. Successful trapping of the aneurysms and excision of the arteriovenous malformation was accomplished with an excellent clinical result. The literature concerning aneurysms of the posterior inferior cerebellar artery, cerebellar arteriovenous malformations, and combined intracranial vascular abnormalities is discussed.
We compared the pulsatile secretion of luteinizing hormone (LH) between 13 men with clinically and electrographically documented temporal lobe seizures and 8 age-matched controls. Serum for LH measurement was drawn every 15 minutes during 8 hours of EEG telemetry in both groups. The 2 groups did not differ significantly in average mean baseline LH secretion, total LH secretion, or average pulse amplitude. The group with seizures, however, showed a significantly greater (p less than 0.05) variability of baseline LH secretion and pulse frequency. Among the men with unilateral paroxysmal EEG findings, pulse frequency was significantly greater (p = 0.05) with right epileptiform discharges or left slowing (6.4 +/- 0.4) than with left epileptiform discharges or right slowing (3.0 +/- 1.3). The relationship of pulse frequency to the nature and laterality of paroxysmal discharges makes it unlikely that endocrine abnormalities can be attributed to medication alone and strengthens the notion that temporal lobe epileptiform discharges may disrupt hypothalamic regulation of pituitary secretion.
Four patients with a solitary vertebral metastasis from a renal cell carcinoma presented with acute spinal cord or nerve root compression. Because of the markedly hypervascular nature of the metastases it was decided to palliate the lesions by transarterial catheter embolization. The embolization reduced the venous blood pool within the tumors, resulting in progressive neurological improvement often lasting for 12 weeks or more. With such palliation, surgical decompression may be obviated, postponed, or at least made manageable.
We studied 31 patients with histologically verified intracerebral cavernous angiomas. Twenty-two patients were symptomatic; nine were asymptomatic. All 22 symptomatic patients had seizures, three had intracranial hemorrhage, and one had signs of a space-occupying lesion. Twenty-seven lesions were located in the neocortex, three in the brainstem, and one in the cerebellum; all exhibited characteristic gross and microscopic features of cavernous angiomas. CT identified the location and extent of the lesion in 16 of 27 cases. Six of seven lesions demonstrated contrast enhancement, and ten of 27 scans harbored densities consistent with intracerebral calcium. Angiography was performed in 17 cases and was completely normal in eight. MRI revealed mixed signal intensity centrally with a ring of decreased signal intensity peripherally on T2-weighted images and was diagnostic in five cases. Surgical treatment offers an excellent prognosis for seizure control in patients with such lesions.
Five cases of histologically verified cavernous angiomas of the spinal cord are reported. Acute lower-extremity sensory disturbance was the initial symptom in four patients, and one presented with weakness of the hand. Progressive neurological deficit occurred in all patients, but the clinical course and outcome were extremely variable. Myelography revealed an intramedullary lesion in two cases but was completely normal in three; magnetic resonance imaging was diagnostic in these patients. Subtotal removal was accomplished in two cases, and myelotomy and biopsy were carried out in three. Four of the cavernous angiomas were located in the cervicothoracic region, whereas one was found in the thoracolumbar cord. All of the patients exhibited characteristic gross and microscopic features as well as hemosiderin-laden macrophages indicating remote hemorrhage. The diagnostic, therapeutic, and prognostic implications of this rare condition are discussed.
Fistulous communication between the vertebral artery and its surrounding venous plexus is rare. Two cases of vertebral arteriovenous fistula following anterior cervical spine surgery are reported. The anatomic relationships of the vertebral vessels, the radiographic findings, and the various therapeutic approaches to these lesions are discussed.
A case of extraaxial ependymoma of the posterior fossa, arising along the inferolateral aspect of the left cerebellar hemisphere, is reported. The clinical, radiologic, and histologic features of this lesion are presented. The unusual location of the tumor and its possible origin are discussed in the light of previous experience with other extraaxial ependymomas of the neuraxis.
We studied 24 patients with autopsy-proven cerebral amyloid angiopathy. Eight patients were demented or had some other medical problem and died of pneumonia or systemic disease. Sixteen patients died of intracranial hemorrhage. Amyloid was found in cortical arteries and arterioles of all patients. CT showed diffuse atrophy in demented patients and intracerebral hematomas in the others. The location and size of the hematoma, with cortical and subarachnoid extension, help to differentiate amyloid angiopathy from other causes of intracranial hemorrhage in the elderly.