Visual field defects after temporal lobe resection: a prospective quantitative analysis

OBJECTIVE

To evaluate and quantify prospectively visual field changes in patients undergoing temporal lobe resections for intractable epilepsy.

BACKGROUND

Visual field abnormalities occur after temporal lobe resections for epilepsy; however, we have not encountered published reports using automated static visual field analysis.

METHODS

Humphrey visual fields (program 30-2) were obtained before and after partial temporal lobe resection in 32 consecutive patients with intractable epilepsy. A quantitative point-by-point analysis was made in the affected superior quadrant, and the defects were averaged for the whole patient group.

RESULTS

Thirty-one patients developed a visual field defect, but none was aware of the defect. The points nearest fixation were relatively spared. The defects were greatest in the sector closest to the vertical meridian in the eye ipsilateral to the resection. The ipsilateral and contralateral mean field defects also differed in both topography and depth. A significant correlation was found between the extent of lateral temporal lobe resection and the degree of the defect in the contralateral eye.

CONCLUSIONS

There are differences in the shape and depth of the ipsilateral and the contralateral field defects not previously reported. These findings demonstrate that certain fibers from the ipsilateral eye travel more anteriorly and laterally in Meyer's loop, and support the hypothesis that visual field defects due to anterior retrogeniculate lesions are relatively incongruous because of anatomic differences in the afferent pathways. Automated perimetry is a sensitive method of evaluating and quantifying visual field defects.

EEG changes in intrathecal baclofen overdose: a case report and review of the literature

OBJECTIVE

To review the clinical and EEG manifestations of intrathecal baclofen overdose.

METHODS

We identified one patient who had received an overdose of intrathecal baclofen. Information about the clinical course was obtained by reviewing the patient's medical record. EEGs were recorded with the use of the standard 10-20 electrode placement system.

RESULTS

The patient received 30 mg baclofen intrathecally. Shortly after the injection he developed respiratory insufficiency and quadriparesis and later became comatose. The first EEG obtained 20 h after the injection showed very frequent quasiperiodic generalized epileptiform discharges. The patient gradually improved clinically and a second EEG obtained 24 h later showed only intermittent bursts of generalized slow wave activity. A repeat EEG study 1 week later was normal.

CONCLUSIONS

The EEG in intrathecal baclofen overdose can show quasiperiodic generalized epileptiform discharges. This does not necessarily indicate the presence of underlying potential epileptogenicity, and treatment with an antiepileptic medication is not necessary.

An analysis of the posterior epidural ligament role on the cervical spinal cord

STUDY DESIGN

Laminectomy was performed on cats to destroy the posterior epidural ligament. Evoked potentials and spinal cord blood flows quantified the spinal cord function before and after cervical flexion.

OBJECTIVES

This work describes a relationship between the loss of the posterior epidural ligaments and cervical spinal cord injury.

SUMMARY OF BACKGROUND DATA

The posterior epidural ligaments of the human cervical spine have been recently described. These ligaments theoretically prevent injury to the spinal cord by resisting collapse of the dura during cervical flexion.

METHODS

The animals were divided into three experimental groups: 1) control: no laminectomy and standard position, 2) flexion control: no laminectomy and known imposed flexion, 3) laminectomy (C3-C7) and flexion. Motor-evoked potentials and evoked spinal cord potentials were recorded to quantify the spinal cord functions. Radioactive microspheres were used to quantify ischemia in the spinal cord.

RESULTS

Control subjects showed blood flows of 36 mL/100 g/min (C3-C4) to 46 mL/100 g/min (C7-C8). Flexion control subjects did not experience significant reductions in blood flows or substantial change in evoked potentials. The laminectomy plus flexion group experienced reduced blood flows and substantial motor-evoked potentials and slight evoked spinal cord potential changes with 50 degrees, 60 degrees, and 70 degrees flexion. Blood flow reduction was greater in the anterior half of the C7-C8 segments compared with the posterior half at 60 degrees flexion. Evoked spinal cord potentials were less vulnerable than motor-evoked potentials.

CONCLUSIONS

The role of the posterior cervical epidural ligaments is to anchor the posterior dura mater to the ligamentum flavum. Loss of the ligaments allows anterior displacement of the posterior dura mater in flexion. Abnormal distribution of or lack of the cervical posterior epidural ligaments may lead to flexion myelopathy.

Postsurgical outcome of patients with uncontrolled complex partial seizures and temporal lobe hypometabolism on 18FDG-positron emission tomography

RATIONAL AND OBJECTIVE

The purpose of this study is to evaluate the relation between a focus of temporal lobe hypometabolism, including comparison between mesial and lateral asymmetry on fluorine-18-labeled-deoxyglucose-positron emission tomography (18FDG-PET) and surgical outcome in patients with uncontrolled partial seizures.

METHODS

Case histories, electroencephalogram (EEG) findings, radiographic findings, and surgical outcome (36 +/- 11 months of follow-up) were reviewed in 38 consecutive patients who had a interictal 18FDG-PET scan and subsequent temporal resection.

RESULTS

Among the 36 patients who had a temporal lobe focus of hypometabolism (more than 15% asymmetry to contralateral side), 61% (22 of 36) became seizure-free, 33% (12 of 36) markedly improved and 6% (2 of 36) did not improve. The focus of hypometabolism on PET was in agreement with the epileptic focus on the noninvasive EEG in 30 of 36 patients and in 19 of the 22 patients who underwent an invasive EEG. The asymmetry index for the mesial temporal lobe was significantly higher in the group of patients who became seizure-free compared with the other patients.

CONCLUSION

This study confirms that a focus of interictal temporal hypometabolism on PET is associated with marked improvement of seizure control after surgery in 94% (34 of 36) of the patients. Hypometabolism in the mesial temporal lobe appears to be associated with a seizure-free outcome.

Global aphasia with seizure onset in the dominant basal temporal region

A 33-year-old right-handed woman had intractable simple and complex partial seizures (SPS, CPS) that began with global aphasia. EEG closed-circuit TV (EEG-CCTV) monitoring with sphenoidal electrodes showed left inferomesial temporal ictal onset of CPS. Subdural electrodes were implanted over the left frontotemporal convexity, subtemporally and subfrontally. Stimulation of the basotemporal cortex produced global aphasia. A posterolaterotemporal language area was also identified. Spontaneous SPS had focal onset in the basal temporal language area (BTLA). Ictal discharges did not involve the posterotemporal region. This case shows that aphasic speech arrest at seizure onset may be due to seizure discharge in the basotemporal region and that the BTLA is clinically relevant in seizure semiology.

Preferential neuronal loss in layer III of the entorhinal cortex in patients with temporal lobe epilepsy

We report a characteristic pattern of neuropathological change in the entorhinal cortex (EC) from four patients with temporal lobe epilepsy. Specimens of the EC were obtained during the surgical treatment of intractable partial seizures and were studied by light microscopy in Nissl-stained sections. A distinct loss of neurons was observed in the anterior portion of the medial EC in the absence of apparent damage to temporal neocortical gyri. Cell loss was most pronounced in layer III, but also noticed in layer II, particularly in the rostral field. A similar pattern of neurodegeneration in the EC was found in all specimens examined though the degree of neuronal loss varied between cases. These observations provide neuropathological evidence for an involvement of the EC in temporal lobe epilepsy. Since the EC occupies a pivotal position in gating hippocampal input and output, our results further support previous suggestions that dysfunction of this region may contribute, either independently or in concert with Ammon's horn sclerosis, to epileptogenesis in humans.

Serial cerebrospinal fluid corticotropin-releasing hormone concentrations in healthy and depressed humans

CRH, a hypothalamic peptide that is the most potent ACTH secretagogue known, also appears to be produced in the cerebral cortex and spinal cord. Depressed patients have blunted responses to exogenous CRH and normal to high concentrations of CRH immunoreactivity in single morning samples of lumbar cerebrospinal fluid (CSF). Although these data suggest that depression may be associated with hypersecretion of CRH, it has also been postulated that central nervous system insufficiency of CRH might have a pathophysiological role in certain depressive syndromes. We continuously sampled lumbar CSF via indwelling subarachnoid catheters from 1100-1700 h and measured CRH at 10-min intervals in depressed patients and normal subjects. A standardized mixed liquid meal was administered at 1300 h. CSF CRH was strikingly reduced in depressed patients compared to normal subjects [4.2 +/- 1.1 pmol/L vs. 13 +/- 2.1 pmol/L (mean +/- SEM), respectively, P less than 0.01 by Wilcoxon test]. CSF CRH concentrations rose progressively during the experiment in both groups, suggesting a diurnal rhythm and, possibly, response to a test meal. CRH had a very brief half-life in CSF (less than 10 min), suggesting that the spinal cord is the origin of CRH in lumbar CSF. The rapid transients in CSF CRH concentration demonstrate that single samples provide very limited information. There were no intraindividual correlations between CSF CRH concentrations and those of either plasma ACTH or cortisol, both of which rose in response to eating. The present data show that impaired central nervous system secretion of CRH can exist during states of severe depression.

Normal and radiculopathic cutaneous pain tolerance levels evaluated by heat-beam dolorimetry

The heat-beam dolorimeter has previously been used to obtain cutaneous pain tolerance measures in normal volunteers and patients with chronic pain. In the present study, normal reference data were collected at two stimulus intensities for 24 volunteers, and the stimulus-effect relationship (decreasing tolerance latency with increasing stimulus intensity) was found significant (p less than 0.001) for all body sites tested. No overall sex differences were found; males behaved slightly more stoically than females, with differences significant only at the T3 site over the breasts. At the second evaluation at the higher stimulus intensity, females exhibited lower pain tolerance (greater pain sensitivity) at the right breast than males (p less than 0.05). No significant lateral asymmetry was found in cutaneous pain tolerance except at the dorsum of the hand: the right hand evinced elevated pain tolerance compared with the left hand in both right- and left-handed subjects. Eight radiculopathic pain patients with clinically involved left L5 nerve roots were evaluated and their responses were compared with the volunteer normal reference data. The radiculopathic group evinced elevated tolerance levels in both the radiculopathic dermatome and noninvolved sites compared with normal individuals (p less than 0.05).

Dural lacerations and thoracolumbar fractures

In the pre-CT era, Miller et al. reported the presence of dural lacerations (DL) and herniations of the cauda equina in a group of patients with thoracolumbar fractures that involved separation of the pedicles, as detailed on plain radiographs. Recently, these injuries have been well characterized on CT scan. We retrospectively reviewed our series of thoracolumbar burst fractures to assess the predictive value of CT for the presence of a DL, and the clinical significance of this finding. Twenty-five patients with 27 levels of injury were assessed. Dural lacerations were noted in eight (32%) of the cases. These were significantly associated with posterior element fractures noted on axial CT, and with motor neurologic deficits. There was no correlation between the presence of a DL and the degree of spinal canal compromise. Dural lacerations occur relatively frequently in patients with thoracolumbar fractures that require operative management. Their presence should be of particular concern in those cases with a motor deficit on presentation and a posterior element fracture on axial CT scan.

Thoracic intervertebral disc herniations: diagnostic value of magnetic resonance imaging

Thoracic disc herniation is relatively rare and frequently poses a challenge in clinical diagnosis. These protrusions have been categorized into two major anatomical types and three main clinical syndromes. A number of characteristic radiographic features have been reported. Recently, magnetic resonance imaging (MRI) has gained popularity as a neurodiagnostic imaging tool. A series of nine cases of thoracic intervertebral disc herniation is reported. The clinical aspects of the cases are discussed, and the potential value of spine MRI for thoracic disc herniation diagnosis is emphasized.

Neurochemistry of the dorsal horn

The dorsal horn region of the spinal cord, particularly the dorsal root entry zone (DREZ), represents the first central integration center for nociceptive afferent impulses. Here, the excitatory neurotransmitters/modulators, products of the primary sensory neurons, are released, the segmental interneuronal influences pertain, and the descending bulbospinal tracts terminate. A vast variety of compounds are thus involved in the processing of nociceptive information in these areas, among which are the 'classical' neurotransmitters and the more recently described neuropeptides. A continued vast interest exists concerning the chemistry of the dorsal horn/DREZ region. The current developments and understanding regarding the pharmacology of this region are presented. Particular emphasis is given to the interactions among the various compounds, the coexistence of some of these within single neuronal populations, the importance of the opiate receptor subtypes, and the actions and localizations of some of the newly discovered neuropeptides.

Combination analgesic-antispasmodic therapy in postoperative pain

Pain and muscle spasms are causes of postoperative complaints and complications following spinal surgery. The traditional medical management makes use of narcotic analgesics. The antispasmodics, diazepam and baclofen, might also be effective in pain control. A randomized prospective study of 50 consecutive patients was conducted comparing a regimen of a narcotic analgesic (meperidine hydrochloride) and the two antispasmodic agents versus the narcotic alone with the hope of reducing the requirement, postoperatively, of the narcotic and also the subjective assessments of pain and/or spasm. The results demonstrate the efficacy of the regimen in relieving postoperative spasm. The percentage of patients requiring narcotics and the assessed pain severity were essentially uniform between the groups. Whereas postoperative spasm was a common lament, it did not represent a significant element of postoperative pain when judged by these criteria.

Percutaneous minidose metrizamide endomyelographic computed tomography in syringomyelia

Two patients presented with syringomyelia, each unusual. After neuroradiographic diagnosis with delayed metrizamide computed tomography (CT) or magnetic resonance imaging (MRI), an interesting diagnostic question arose. A percutaneous minidose metrizamide endomyelographic CT (PMDMECT) study clarified each situation and directly affected the neurosurgical approaches. The features of each case, the technique of PMDMECT, and postoperative follow-up data are reported.

Craniotomy flap osteomyelitis: a diagnostic approach

Nine cases of suspected craniotomy flap osteomyelitis evaluated by combined bone and gallium scanning are presented. In six cases, the clinical data were inconclusive and evaluation by radionuclide imaging provided an accurate negative diagnosis. The other three cases considered positive by this technique were proven infected at subsequent exploration and flap removal. The use of radionuclide bone and gallium imaging should be considered in cases of possible craniotomy flap osteomyelitis.

Meningeal neurosarcoidosis mimicking convexity en-plaque meningioma

A 34-year old man presented with headaches. Computed tomography scanning revealed an enhancing subdural mass extending from the skull base to the convexity, thought to represent an en-plaque meningioma. Pathologic study revealed extraaxial subdural granulomatous inflammation consistent with neurosarcoidosis.

Primary leptomeningeal gliomatosis and "numb, clumsy hands": a case report

A 48-year-old man presented with the numb, clumsy hand syndrome. Evaluation revealed a high cervical cord lesion. Surgical exploration discovered leptomeningeal gliomatosis with no discernible intraparenchymal component. The clinical features of the case, the neuroimaging studies including magnetic resonance scanning, and the most unusual pathological nature of the lesion are discussed.

Ocular bobbing with ruptured giant distal posterior inferior cerebellar artery aneurysm

A patient presented comatose with an intraventricular hemorrhage of unknown etiology, and manifested the unusual clinical phenomenon of ocular bobbing. Further evaluation revealed a giant aneurysm of the distal posterior inferior cerebellar artery, which was successfully treated surgically. The pathophysiology of ocular bobbing is discussed as well as the association of this unusual sign with a rare aneurysm.

Tuberous sclerosis and multiple intracranial aneurysms: case report

A 6-year-old girl with tuberous sclerosis was found to have multiple intracranial fusiform arterial aneurysms. This represents the fifth reported case of this association. The concepts of an arterial dysplasia being present in cases of tuberous sclerosis and of developmental defects being the cause of some intracranial aneurysms are discussed. The need for a prospective study to assess the prevalence of intracranial aneurysms in patients with tuberous sclerosis is suggested.

Computed tomography detection of cervical spinal cord hemangioblastoma: a case report

Hemangioblastomas of the spinal cord are uncommon, accounting for 1.6% and 2.1% of all spinal cord tumors (1). Until recently these vascular lesions were best evaluated angiographically. Several cervical hemangioblastomas have been studied by computed tomography with intravenous contrast medium enhancement (2-4). This report illustrates the use of computed tomography with combined intravenous and intrathecal contrast medium enhancement, which permitted preoperative diagnosis and treatment planning of an intramedullary hemangioblastoma.

Neuropharmacology of the dorsal root entry zone

The finding of a number of peptides in the central nervous system and the discovery of the endogenous opiates represent major recent advances in the understanding of neural transmission. A number of these neuropeptides are found in the dorsal root entry zone and may play a role in pain. An analysis of changes in distribution of substance P, methionine-enkephalin, and somatostatin after simulated nerve root avulsion injury suggested a possible mechanism for deafferentation pain. A review of the localizations and actions of these peptides in the dorsal root entry zone is included.

Neck paraganglioma with a pituitary adenoma. Case report

✓ A 66-year-old man presented for evaluation of a mass of the sella turcica. Previously, he had undergone resection of a neck paraganglioma, which subsequently metastasized to the lungs. A tumor was removed transsphenoidally that proved to be a pituitary adenoma. This combination failed to fit the classical multiple endocrine neoplasia syndromes.