A study of tremor in multiple sclerosis.

One hundred patients with definite multiple sclerosis, who were randomly selected from a multiple sclerosis unit in London, were examined in order to study the prevalence, subtypes, clinical features and associated disability of tremor in this population. There were 35 males and 65 females with an average age of 47 years and an average disease duration of 18.8 years. The mean tremor duration was 13 years, with a median latency of 11 years from disease onset to appearance of tremor. Tremor was reported in 37 patients but was detected in 58. Tremor affected the arms (56%), legs (10%), head (9%) and trunk (7%). There were no examples of face, tongue or jaw tremor. All the patients had action tremor, either postural or kinetic (including intention). Rest, Holmes' ('rubral') and primary orthostatic tremors were not encountered. Tremor severity ranged from minimal in 27%, to mild in 16% and moderate or severe in 15% of cases. Tremor severity correlated with the degree of dysarthria, dysmetria and dysdiadochokinesia but not with grip strength. In order to determine the clinical characteristics of these tremors, the action tremors of the upper limbs were subclassified according to the predominant site and state of tremulous activity. Of the 50 patients with tremor in the right arm, 32% had distal postural tremor, 36% had distal postural and kinetic tremor, 16% had proximal postural and kinetic tremor; 4% had proximal and distal postural and kinetic tremor and 12% isolated intention tremor. Twenty-seven percent of the overall study population had tremor-related disability and 10% had incapacitating tremor. Patients with abnormal tremor (severity grade >1/10) were more likely than those without tremor to be wheelchair dependent and have a worse Expanded Disability Systems Score, but Barthel activities of daily living indices and cognitive scores were comparable in the two groups.