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Background Axonal loss is a major determinant of disability in multiple sclerosis (MS). While acute inflammatory demyelination is a principal cause of axonal transection and subsequent axonal degeneration in acute disease, the nature of chronic axonal loss is less well understood. In the current study, the relationship between degree of chronic demyelination and axonal degeneration was investigated using optic neuritis (ON) as a model. Method 25 patients with a first episode of unilateral ON, good recovery of visual function and concurrent brain or spinal cord MRI lesions were enrolled. Axonal loss was assessed using change in retinal nerve fibre layer (RNFL) thickness between 1 and 3 years after ON. Optic nerve conduction was evaluated using latency of multifocal visual evoked potentials (mfVEP). The level of mfVEP latency delay at 12 and 36 months was considered indicative of the degree of permanent demyelination. Data from 25 age and gender matched normal controls were used for comparison. Results RNFL thickness was significantly reduced in ON eyes at 12 months compared with controls but remained unchanged in fellow eyes. Average RNFL thickness demonstrated a small but significant reduction between 12 and 36 months for both ON and fellow eyes. Change in RNFL thickness between 12 and 36 months, however, did not correlate with the degree of mfVEP latency delay. Conclusion The results, therefore, show no association between the degree of permanent optic nerve demyelination (as measured by latency delay) and progressive axonal degeneration, at least in the early stages of the disease. The fact that fellow eyes demonstrated a similar degree of progressive axonal loss supports this suggestion. [ABSTRACT FROM AUTHOR]

The clinical manifestations of mitochondrial encephalomyopathy are described in four generations of a single kindred. The age of onset of major neurological disturbance varied from 3-70 years. In some patients, deafness was the only manifestation; in others, recurrent bouts of status epilepticus associated with focal neurological deficits and headache, caused severe disability or death. Examples of all three adult forms of mitochondrial encephalomyopathy: MELAS, MERFF and Kearns Sayre syndrome, were represented within the kindred. Associated features included deafness, short stature, non-insulin-dependent diabetes mellitus, migraine, peptic ulceration and severe constipation. The nt 3243 A-G MELAS mutation was detected in two members of the kindred. This study highlights the diversity of clinical expression of a mitochondrial mutation within a single kindred. [ABSTRACT FROM AUTHOR]

Median nerve somatosensory evoked potentials (SEPs) were performed on 35 patients with acute stroke and correlated with functional outcome as measured by placement, length of stay and an activities of daily living index (Barthel Index). There was a statistically significant correlation of both SEP and sensory examination at the 0.05 level to eventual functional outcome. SEPs were better than age, sex and side of CVA in predicting functional outcome as measured by these scores. SEPs and sensory examination are interrelated but SEPs offer the advantages of objectivity, the ability to quantify results and the use in unconscious or dysphasic patients. [ABSTRACT FROM AUTHOR]

Somatosensory evoked potentials were recorded over the lumbar spine and scalp in 12 normal subjects after stimulating the posterior tibial nerve at the knee and ankle and the sural nerve at the ankle. The H-reflex from the soleus muscle was recorded at the same time. The effects of stimulus intensity, frequency of stimulation and vibration were assessed. It was concluded that when the posterior tibial nerve was stimulated in the popliteal fossa, three negative peaks were recorded over the lumbosacral area. They arose from activity in the dorsal roots, the dorsal horn of the spinal cord (SD) and the ventral roots. In contrast when the posterior tibial nerve and the sural nerve were stimulated at the ankle only two negative peaks were recorded, a dorsal root potential and a spinal cord dorsum potential. In addition the data suggested that the peripheral nerve fibres that are involved with generating the surface recorded spinal potential with mixed nerve stimulation are primarily muscle afferents. [ABSTRACT FROM AUTHOR]

Motor and sensory conduction studies, F-wave latency, and the latency of evoked potentials from the brachial plexus and cervical spine in response to median nerve stimulation were examined in 17 patients with acute idiopathic polyneuropathy. Short latency evoked potentials provided a higher yield of evidence of abnormalities of proximal conduction than did the F-wave latency. Both methods of studying conduction in the proximal segments of a peripheral nerve may be normal, however, in a small number of patients who have significant pathological lesions. [ABSTRACT FROM AUTHOR]

A study of 10 patients with brachial plexus trauma was performed to determine whether the diagnostic accuracy of sensory evoked potentials (SEPs) may be improved by using stimulation of multiple peripheral nerves (median, radial, musculocutaneous and ulnar). In addition, the relative advantages of SEPs and peripheral electrophysiological studies were considered. SEP patterns following most common brachial plexus lesions were predictable. Injuries to the upper trunk affected the musculocutaneous and radial SEPs predominantly. Lower trunk or medial cord lesions primarily affected ulnar SEPs. Diffuse brachial plexus lesions affected SEPs from all stimulation sites. In the majority of cases, the necessary information was obtainable from conventional EMG: however, for lesions involving the upper segments only, SEP techniques were more useful. It is suggested that selective SEPs from appropriate peripheral nerves when interpreted in combination with conventional EMG may add useful additional information. [ABSTRACT FROM AUTHOR]

A study was made of 11 patients with cervical rib, and one patient with Klippel-Fiel syndrome and enlarged transverse processes to determine whether evoked potentials recorded from both Erb's points and the cervical spine in response to median and ulnar nerve stimulation provided information additional to that obtained by EMG and peripheral conduction studies. It was found that in seven patients who had pain and paraesthesias but no objective neurological signs both the peripheral and central conduction studies were within normal limits. By contrast, of five patients who had objective signs, conventional EMG and conduction studies were abnormal in three patients, but abnormalities of the evoked potentials obtained from ulnar nerve stimulation were obtained in all five patients. It is suggested that this application of evoked potential estimation is a useful addition to the more conventional peripheral investigations. [ABSTRACT FROM AUTHOR]

Lower motor neuron (LMN) syndromes typically present with muscle wasting and weakness and may arise from pathology affecting the distal motor nerve up to the level of the anterior horn cell. A variety of hereditary causes are recognised, including spinal muscular atrophy, distal hereditary motor neuropathy and LMN variants of familial motor neuron disease. Recent genetic advances have resulted in the identification of a variety of disease-causing mutations. Immune-mediated disorders, including multifocal motor neuropathy and variants of chronic inflammatory demyelinating polyneuropathy, account for a proportion of LMN presentations and are important to recognise, as effective treatments are available. The present review will outline the spectrum of LMN syndromes that may develop in adulthood and provide a framework for the clinician assessing a patient presenting with predominantly LMN features., Competing Interests: Competing interests: None declared., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)