Delayed cervical spinal cord tethering following tonsillar resection for Chiari malformation.

Although tethering of the spinal cord in the lumbosacral region, particularly following repair of congenital anomalies, such as myelomeningocele, is a well-known phenomenon, only sporadic reports of tethering along the rest of the neuraxis, including the hindbrain, cervical and thoracic spinal cord have been documented. In this report, we describe a woman who developed symptoms related to tethering of the cervical spinal cord 5 years after suboccipital decompressive surgery of the posterior fossa for Chiari I malformation. The authors discuss the diagnosis, treatment, and postoperative course of this entity.

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.

Differential diagnosis of severe back pain using MRI.

Back pain, despite its prevalence, often presents a diagnostic dilemma. Infection, degeneration, and neoplasm comprise major etiologic categories of severe nonspecific back pain. Diagnostic evaluation includes plain roentgenograms, computerized tomography, and radionuclide studies, all of which are often equivocal or misleading. We retrospectively analyzed 21 presentations of severe back pain of various causes evaluated by magnetic resonance imaging (MRI) in addition to conventional diagnostic imaging modes. A characteristic MRI pattern of both the lesions's distribution and its signal intensity was observed that delineated each etiologic category. MRI was found to be particularly suited for use in the differential diagnosis of nonspecific back pain.

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.

Intraoperative ultrasonography (IOUS) in thoracolumbar fractures.

The thoracolumbar levels are the second most common region for spinal trauma. A major surgical effort often entails removal of retropulsed bone fragments with decompression of the spinal contents or realignment of vertebral subluxations. The ability to determine intraoperatively the completeness of such a procedure could impact on the surgical approach and, ultimately, the operative result. The intraoperative use of ultrasonography has gained popularity and applicability. This comparison study of intraoperative ultrasonography versus postoperative computed tomography (CT) assessed the accuracy of intraoperative ultrasonography in determining the status of the spinal canal following surgical intervention in a group of 21 patients with thoracolumbar fractures. In all cases a patent ventral subarachnoid space or complete spinal canal decompression was deduced following intraoperative ultrasonography. The postoperative assessment by CT concurred in 20 of 21 (95%) situations. Intraoperative ultrasonography proved useful during the operative management of these fractures and gave good supportive evidence that the neural elements were decompressed by surgical procedure.

Magnetic resonance imaging (MRI) of thoracolumbar fractures.

Many patients suffer neurologic deficits as a consequence of thoracolumbar fractures. A major surgical effort often entails decompression of the neural elements. Which patients would benefit from this endeavor remains to be determined. Magnetic resonance imaging (MRI) has emerged as one of the foremost neurodiagnostic procedures. This study assessed the impact of MRI on the management of these injuries in 21 patients. Five anatomical parameters were evaluated. Significant associations were noted between the neurologic morbidity from the injury and (a) the relative level of the conus medullaris and; (b) the patency of the ventral subarachnoid space. On the basis of these data, a treatment protocol is presented. MRI has gained prominence as an investigative tool in cases of thoracolumbar trauma.

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.