We compared the diagnostic capabilities of contrast reversal and sparse pattern pulse stimulation for dichoptic multifocal visual evoked potentials (mfVEPs) measured in normal subjects and multiple sclerosis (MS) patients. Multifocal responses were obtained from 27 normal subjects and 50 relapsing-remitting patients, 26 of whom had experienced optic neuritis (ON+). The patient groups were matched for length of disease and number of clinical attacks. Compared with the responses of normal subjects those of MS patients had significantly smaller response amplitudes, lower signal-to-noise ratios, more complex response waveforms, and longer response delays. The effects were larger for sparser stimuli. Sensitivities and specificities for the different stimulus types were estimated from receiver operator characteristic (ROC) plots. Bootstrap estimates of the accuracies of the ROCs for the most promising measure, the template delays, indicated the sparsest stimulus would deliver 92% sensitivity at a false-positive rate of 0%. In contrast, at 92% sensitivity the conventional mfVEP stimulus misdiagnosed more than 20% of the normal population. The results were similar for patients with no history of ON (ON-). In performing well in patients with no history of ON, the sparse mfVEPs seem to measure progressive damage associated with axon and gray matter losses rather than damage associated with a history of serious inflammation.

Summary:Purpose: Lamotrigine (LTG) is recognised as effective add-on therapy for focal epilepsies, but this is the first double-blind, placebo-controlled, crossover study in treatmentresistant generalised epilepsy.Methods: The study consisted of 2 x 8-week treatment periods followed by a 4-week washout period. Patients received doses of either 75 or 150 mg daily, depending on their concomitant antiepileptic drugs (AEDs). Long-term continuation was offered at the end of the study with open-label LTG.Results: Five centres in Australia recruited 26 patients who were having absence, myoclonic, or generalized tonic-clonic seizures or a combination of these. Twenty-tv?o patients completed the study. There was a significant reduction in frequency of both tonic-clonic and absence seizure types with LTG. A 250% decrease in seizures was observed for tonic-clonic seizures in 50% of cases and for absence seizures in 33% of evaluable cases. Rash was the only adverse effect causing discontinuation. Twenty-three of 26 opted for open-label LTG, with 20 still receiving LTG for a mean of 26 months. In these 20, 80% had 250% seizure reduction and five (25%) were seizure free.Conclusions: This study shows that LTG is effective add-on therapy in patients with refractory generalised epilepsies. Statistically significant reduction in seizures in both absence and tonic-clonic seizure types was seen even with low doses of LTG.

SUMMARY A small pneumatic cuff inflated around the knee was used to produce tourniquet paralysis in baboons. A cuff pressure of 1,000 mm Hg maintained for one to three hours produced paralysis of distal muscles lasting up to three months. Nerve conduction studies showed that most of the motor fibres to the abductor hallucis muscle were blocked at the level of the cuff and that they conducted impulses normally in their distal parts. There was a significant correlation between the duration of compression and that of the subsequent conduction block. When tested two to three weeks after the tourniquet, the amplitude of the response of m. abductor hallucis to nerve stimulation distal to the cuff was usually slightly reduced compared with the precompression figure. This was assumed to mean that a small proportion of the motor fibres had undergone Wallerian degeneration as a result of compression. Maximal motor conduction velocity was reduced in recovering nerves. It was also reduced when a cuff pressure of 500 mm Hg was used, which was insufficient to produce persistent conduction block. In such cases a reduced velocity without evidence of block could be demonstrated 24 hours after compression. Ascending nerve action potentials were recorded from the sciatic nerve in the thigh, with stimulation at the ankle. Before compression the fastest afferent fibres had a significantly higher velocity than the fastest motor fibres in the same nerve trunk. Results after compression suggested that the high-velocity afferent fibres had a susceptibility to the procedure similar to that of the fastest motor fibres.In clinical practice, particularly in orthopaedic surgery, it is well recognized that the application of a tourniquet to a limb is sometimes followed by paralysis which may persist for weeks or months. While most of the reports in the literature date from the period when rubber tubing or Esmarch bandages were used (Lejars, 1912;Eckhoff, 1931), occasional examples have been reported after pneumatic tourniquets (Bruner, 1951;Moldaver, 1954 by Denny-Brown and Brenner in 1944. They found that there was local demyelination of nerve fibres under the tourniquet but no loss of axonal continuity through the lesion. The electrical excitability of the motor nerves distal to the tourniquet was preserved, and in most cases power in the affected muscles recovered within a few weeks. Conduction velocity during the recovery period was studied by Mayer and Denny-Brown (1964) who found it to be reduced at the site of the tourniquet compared with the velocity above and below this level.In the present experiments we have reinvestigated the conduction block produced by a tourniquet, with special reference to the timecourse of recovery. In baboons it has been possible to apply a pneumatic cuff rather than the narrower rubber tubing used by Mayer and Denny-Brown in the cat. Recovery in individual 638

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