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Magnetic stimulation was used to measure motor conduction time (MCT) between head and neck in a prospective longitudinal study of patients with multiple sclerosis (MS) and normal subjects. MCT measurements showed a high degree of reproducibility in normal subjects and patients with stable MS. In patients with definite MS, there was significant positive correlation between MCT and motor disability. In patients treated with steroids for relapse of MS, there was significant shortening of MCT following treatment in those who clinically improved, but not in those who were clinically unchanged. In a smaller group of patients followed for 3 months, MCT changes tended to mirror the clinical pattern. Magnetic stimulation should prove a useful tool for the quantification of motor disability, and monitoring the response to new treatments in MS.

Magnetic stimulation was used to measure motor conduction time (MCT) between head and neck, and head and lumbar region, as well as amplitude of the motor evoked potential (MEP) in normal subjects and patients with multiple sclerosis (MS). Patients with definite MS had significantly longer MCTs and smaller amplitude MEPs than normal subjects when recording from arm and leg muscles. In a comparison with visual evoked potential (VEP) recordings, head to neck MCTs were abnormal less often than VEPs, and VEPs detected more silent lesions. Recording from leg as well as arm muscles significantly increased the yield of abnormal MCT measurements. The detection of silent lesions in the patients with definite MS was improved, but there was no improvement in the non-definite cases. Amplitude measurements provided very little extra diagnostic information over MCT measurements alone and did not improve the detection of silent lesions. Interside MCT differences yielded extra abnormalities when recording from the arms but not the legs. Interside MCT abnormalities increased the detection of silent lesions in both the definite and non-definite categories. It was concluded that the majority of useful diagnostic information in patients with MS should be obtainable from bilateral MCT (head to neck) measurements, together with estimation of interside MCT differences. However, VEP recording is a better diagnostic test for MS than MEP recording as more silent lesions are detected. This may be because MCT abnormalities tend to reflect the degree of pyramidal disability.

The new technique of magnetic stimulation was used to measure amplitude of the motor evoked potential (MEP) recorded from abductor digiti minimi whilst stimulating at the head, and motor conduction time (MCT) between head and neck. Bilateral studies were made in 12 normal subjects and 56 patients with Parkinson's disease. The amplitudes of the MEPs were significantly larger (P less than 0.05) in the patients (mean 1.6 mV, SD 1.4) compared with the normal subjects (mean 0.9 mV, SE 0.6). MCTs were significantly shorter (P less than 0.001) in patients (mean 8.1 ms, SD 1.3) compared with the normal subjects (mean 9.4 ms, SD 1.2). Although the pathophysiological basis of these changes has not been determined, they provide objective measurements which may be clinically valuable in monitoring therapy.

Although the pathophysiological basis of idiopathic focal dystonia (IFD) remains unclear, we recently reported abnormal perception of the tonic vibration reflex (TVR) in the biceps brachii in IFD. In this study we examined whether the abnormality affects muscles other than the biceps brachii. A 100-Hz vibration stimulating predominantly the muscle spindle afferent was transcutaneously applied to one muscle tendon of the triceps brachii, the wrist extensor and flexor muscles in 29 subjects with IFD (18 with torticollis, 9 with writer's cramp, 2 with blepharospasm) and 15 control subjects. The blindfolded subjects were instructed to copy any perceived movement with the opposite tracking arm. The elbow or wrist angle changes were quantified electronically. The TVR and subjects' perception of the TVR were evaluated by angle movements of the vibrated joint and of the tracking joint, respectively. Perception of the TVR was significantly reduced in dystonic subjects at both elbow and wrist joints, while magnitude of the TVR did not differ between the two groups. Abnormal central perception of the TVR is a feature of IFD, suggesting a widespread involvement of abnormal muscle spindle afferent processing in IFD.

Total lymphocyte counts and T and SIg+ cell numbers in peripheral blood were determined in 74 healthy controls and 44 MS patients. Twenty-five patients were studied in relapse and at two intervals after ACTH. Nineteen had not relapsed for 6 months but most had progressed clinically. MS patients showed significantly lower total lymphocyte counts which were not correlated with disease activity. Subpopulation analyses showed the MS patients to have significantly lower T cell numbers and significantly elevated SIg+ cell numbers and percentages. Although T cell numbers were low in all phases, both T and SIg+ cell abnormalities were maximal in progressive disease or in the recovery phase after relapse and a significant fall in T cell percentage and rise in SIg+ cell number was confirmed in serial studies of 16 patients followed from relapse to recovery. SIg+ cell numbers correlated negatively with relapse rate and correlated positively with the ratio of disability to number of relapses. The incidence in MS patients of HLA A3 was significantly increased and of HLA B12 and HLA BW40 significantly decreased but no correlation was seen between HLA phenotype and T, SIg+ or total lymphocyte counts. It is suggested that the peripheral blood SIg+ cell abnormalities and some of the T cell abnormalities are secondary to the pathological process, perhaps due to antigenic stimulation and particularly in non-relapsing progressive disease. Their possible role in influencing recovery or progression is discussed.

The relationship between serum and CSF IgG has been analysed: 1. (1) In patients with a normal CSF concentration of albumin, no correlation can be demonstrated between serum IgG and CSF IgG. 2. (2) In cases where the CSF albumin concentration is elevated (i.e. transudation), local synthesis of IgG can be determined by reference to the degree of transudation of albumin and the serum IgG concentration. The combination of local IgG synthesis and transudation (meningitic pattern) is common. Most pure transudates are of “non-inflammatory” type. A very simple formula is proposed which evaluates the relationship between local and general immunity in all neurological diseases.