The rationale, basic considerations, and technique of intraoperative nerve action potential (NAP) recording have been reviewed. Experience using this technique in several thousand patients over a 25 year period has been summarized. The most frequent serious nerve injury is one that leaves it in continuity. Resection of such a lesion that is regenerating does the patient a great disservice as does exploration without repair of one with little or no potential for useful spontaneous recovery. The frequency of lesions in continuity as well as the difficulties in evaluating them in the early months by electromyography let alone by surgical inspection has led to the development of intraoperative NAP recording. Where neurolysis was based on a recordable NAP across a lesion in continuity, 93% recovered good function. Where resection of the lesion was based on absence of an NAP, the injury was, without exception, neurotmetic and/or one with poor potential for useful recovery without repair. Some lesions had an NAP across their lesion but a portion of the cross-sectional area appeared more seriously injured. By use of NAP recordings, a split repair was done and usually with good results.

Motor evoked potentials (MEPs) were recorded from selected non-wasted, non-denervated hand muscles in 40 patients with Amyotrophic Lateral Sclerosis (ALS) with both upper and lower motor neuron signs. In most the compound muscle action potential (CMAP) of the target muscle was normal. Compared to the control group, cortical threshold in ALS varied considerably and there was a significant (r2 = 0.702) inverse, exponential, correlation between cortical threshold and MEP/CMAP ratio. There was a linear correlation between threshold and disease duration (r2 = 0.66) so that early in the disease threshold was normal and later the motor cortex could not be stimulated. It is suggested that early in ALS normal threshold reflects glutamate-induced hyper-excitability of the corticomotoneuron. The findings lend support to the hypothesis that ALS is primarily a disease of the corticomotoneuron.

The decisive conclusions to be drawn from the available epidemiological data, mostly geography and prevalence, of MS are: (1) a north-south (as well as west-east in the United States) gradient exists independent of genetic/racial factors; (2) major differences in prevalence occur in the absence of latitude differences; (3) individuals from the same ethnic derivation have either similar prevalence rates or very different prevalence rates in widely separated geographical areas and (4) specific resistant isolates are shown to exist regardless of latitude. Existing information leads to the almost inescapable conclusion that the epidemiology of MS cannot be explained by any single known environmental or genetic factor(s) in isolation. A combination of a heterogeneous distribution of both genetic and environmental factors appears to be required to explain the available data on MS.

The effect of hemodilution, with α-α cross-linked hemoglobin (DCLHb), on brain injury and edema was assessed after temporary middle cerebral artery occlusion in rats. Injury was analyzed with 2,3,5-triphenyltetrazolium chloride (TTC) stain and edema by microgravimety. Part A: DCLHb was given to maintain one of the following hematocrits (Hct) and normotension: 1) 45/Hct, 2) 30/Hct, 3) 16/Hct, or 4) 9/Hct. Brain injury (% of ischemic hemisphere, mean ± SD) was less in the 30/Hct group (31 ±4) versus the 45/Hct group (42 ± 5); and in the 16/Hct (20 ± 3) and 9/Hct (19 ± 4) groups versus the 45/Hct and 30/Hct groups. Edema was less in the hemodiluted groups versus the 45/Hct group. Part B: DCLHb was given to maintain one of the following hematocrits and hyper (HTN) − or normotension (Norm): 1) 45/Norm, 2) 30/Norm, 3) 30/HTN, 4) 16/Norm, or 5) 16/HTN. In hematocrit matched groups hypertension decreased brain injury (30/HTN − 24 ± 2 < 30/Norm − 34 ± 4; and 16/HTN − 17 ± 3 < 16/Norm − 24 ± 4). Edema was not effected by hypertension. These results suggest that hemodilution with DCLHb decreases focal ischemic injury, and is most effective when given in a manner that induces hypertension.

Occlusion of the carotid arteries for 5 minutes in the Mongolian gerbil results in selective necrosis of CAI pyramidal neurons. In the present experiments we studied whether intraventricular infusion of acidic fibroblast growth factor (aFGF) could attentuate this damage. Intraventricular infusions of bovine serum albumin (BSA-10 ng/h) or aFGF (1, 10 or 100 ng/h) were started 2 days prior to 5 minutes of bilateral carotid occlusion and continued for 5 days post-ischemia. The brains were perfused and fixed at 5 days post-ischemia and histological assessment of CAI damage was made. Animals receiving intraventricular infusions of 10 or 100 ng/h aFGF showed a significant reduction of CA1 neuronal damage in comparison to no treatment ischemic controls (no treatment − 8 + 1 ; aFGF 10 ng/h − 147 ± 28; aFGF 100 ng/h − 168 ± 35 cells/mm CAI; P < 0.05 for both aFGF groups). The results indicate that aFGF infusion can attenuate the severity of ischemic neuronal necrosis in the gerbil hippocampus.

In this study the ability of iron chelators to attenuate hypoxic-ischemic brain damage was assessed in hyperglycemic rats that were exposed to 1% carbon monoxide and right carotid occlusion. The animals received deferoxamine (50 mg/kg), manganese-deferoxamine (50 mg/kg) or vehicle i.p. 0.5 h prior to hypoxemic-ischemic exposure and at 0.5, 3 and 24 h post-exposure; with subsequent histological examination of the brain at 7 days recovery. The area of cerebral infarction was measured at three levels using video imaging methods. The mean percentage of total hemisphere that was infarcted in the three groups was: vehicle — 28.5 ± 5.0; deferoxamine — 31.7 ± 12.1; and manganese deferoxamine — 30.6 ± 6.8 (p - n.s.). The results as obtained in this preliminary study indicate that aggressive pre- and post-treatment with iron chelators has no ability to attenuate cerebral infarction in this model.

A single-blind study of dystrophin staining in skeletal muscle was performed in 13 biopsies from carriers of Duchenne Muscular Dystrophy (DMD) and controls. The results indicate that immunohistochemical analysis of dystrophin staining is a valuable diagnostic test for DMD carriers when DNA for testing is unavailable from critical family members or is uninformative, when creatine kinase (CK) values are conflicting or when CK values must be used in isolation.

The presence of cortical senile plaques and neurofibrillary tangles sufficient to warrant a neuropatho-logical diagnosis of Alzheimer's disease is well established in middle-aged individuals with Trisomy 21 (Down's syndrome). In contrast a relationship between Down's syndrome and Lewy bodies, one of the major neuropathological features of Parkinson's disease, has not been previously reported. In a cliniconeuropathological survey of 23 cases of Down's Syndrome, two patients, aged 50 and 56 years respectively, were found to have Lewy body formation in the substantia nigra in addition to cortical Alzheimer-type pathology. Neither case showed significant substantia nigra neuron loss although locus coeruleus loss was present in both. Since substantia nigra Lewy bodies are a characteristic neu-rohistological feature of idiopathic Parkinson's disease, their occurrence in cases of Down's syndrome with evidence of Alzheimer-type pathology supports an aetiopathological connection between Parkinson's disease, Alzheimer's disease, and Down's syndrome; and suggests that common pathogenic mechanisms may underlie aspects of neuronal degeneration in these three disorders, some of which may relate to aberrant chromosome 21 expression.

We performed a double-blind cross-over study with amantadine hydrochloride in 12 patients with Friedreich's disease and 2 with autosomal dominant cerebellar ataxia. Patients were randomly assigned to a placebo-amantadine or amantadine-placebo sequence. The interval between the treatments was two weeks. Patients were graded according to a functional ataxia scoring scale and videotaped in basal conditions and 90 min after a single oral dose of 100 mg amantadine or placebo. Three evaluators independently scored the videotapes. Statistical analysis showed no significant effect of amantadine in Friedreich's disease.

The anterior interosseous neuropathy is a rare focal neuropathy with typical clinical and electromyographic features. Most commonly reported etiologies include lesion of the median nerve following fracture of the radius and ulna, acute or repeated trauma or prolonged pressure on the forearm. In some cases, no predisposing factors can be elicited. Over a one-year period, two young women in their late twenties were evaluated for weakness of the flexor pollicis longus, flexor digitorum profundus of the 2nd and 3rd fingers, and pronator quadratus muscles that occurred within a month following parturition. Nerve conduction studies and concentric needle electrode examination of the upper extremities performed respectively 3 and 10 months after the onset of symptoms confirmed a severe anterior interosseous neuropathy and excluded more common conditions such as carpal tunnel syndrome, cervical radiculopathy or brachial plexopathy. The prognosis was unfavorable in both cases.

This report highlights the clinical features of two patients who presented with severe neuropathic chest wall pain caused by herniated C6-7 disc, and speculates on the pathophysiology of this syndrome. Worsening of symptoms with neck movement helped localize the process as cervical spine rather than plexus in origin. Both patients had herniated C6-7 disc material compressing the spinal cord and C7 nerve root, and neurological symptoms resolved promptly following surgery. Neuropathic chest wall pain should alert the clinician to consider the diagnosis of cervical disc herniation and prompt definitive imaging of the cervical spine by myelography or magnetic resonance imaging (MRI).

A 59-year-old man presented with the acute onset of paresthesias and pain in the left neck, face, and forehead. On subsequent investigation he was found to have a subadventitial type of carotid artery dissection, producing an ipsilateral Horner's syndrome with normal carotid angiography. MRI imaging of the neck structures, using fat saturation technique, showed the subadventitial dissection, sparing the vessel lumen. MRI offers a non-invasive method of diagnosis and follow-up for carotid artery dissection.

A patient presented with myelopathy due to intramedullary thoracic spinal cord glioblastoma 10 months after treatment for a supratentorial glioblastoma. There was no supratentorial recurrence, and no evidence of gross leptomeningeal dissemination documented by CSF cytology, complete myelography, and MR1 imaging. Gross examination of the spinal cord and arachnoid at the time of exploratory thoracic spinal surgery was normal. However, histological review of thoracic arachnoid demonstrated microscopic deposits of glial fibrillary acidic protein (GFAP) positive tumour consistent with malignant astrocytoma. Intramedullary spinal cord metastasis of cerebral glioblastoma rarely occurs, but may develop in association with leptomeningeal tumour dissemination. As local control of primary tumours improves, distant metastasis is likely to become a more common clinical problem. Leptomeningeal gliomato-sis may be very difficult to document, even when clinically suspected and GFAP staining of a biopsy of arachnoid tissue can play an important role in confirming the diagnosis. This information can be critical to establish prognosis and develop an appropriate treatment strategy.

Neuropathic pain is not well understood. Although central dorsal horn remodelling is likely important in maintaining chronic neuropathic pain, afferent activity from injured nerves or ganglia may initiate these changes. It is suggested, in this review that the peripheral nerve trunk is capable of sustaining a “flare” response as observed in injured skin and other tissues. The injury response may be associated with local vasodilatation, plasma extravasation and the generation of painful local afferent activity sustained by locally originating peptidergic fibers (nervi nervorum). These fibers contain substance P, calcitonin gene-related peptide and other peptides that have been linked to nociceptive transmission. Manipulation of the local injury response of the nerve trunk by pharmacologic means may provide one strategy in the treatment of neuropathic pain.