Chronic deep brain stimulation for the treatment of tremor in multiple sclerosis: review and case reports.

BACKGROUND: Deep brain stimulation (DBS) offers a non-ablative alternative to thalamotomy for the surgical treatment of medically refractory tremor in multiple sclerosis. However, relatively few outcomes have been reported. OBJECTIVE: To provide a systematic review of the published cases of DBS use in multiple sclerosis and to present four additional patients. METHODS: Quantitative and qualitative review of the published reports and description of a case series from one centre. RESULTS: In the majority of reported cases (n=75), the surgical target for DBS implantation was the ventrointeromedial nucleus of the thalamus. Tremor reduction and improvement in daily functioning were achieved in most patients, with 87.7% experiencing at least some sustained improvement in tremor control postsurgery. Effects on daily functioning were less consistently assessed across studies; in papers reporting relevant data, 76.0% of patients experienced improvement in daily functioning. Adverse effects were similar to those reported for DBS in other patient populations. CONCLUSIONS: Few of the studies reviewed used highly standardised quantitative outcome measures, and follow up periods were generally one year or less. Nonetheless, the data suggest that chronic DBS often produces improved tremor control in multiple sclerosis. Complete cessation of tremor is not necessarily achieved, there are cases in which tremor control decreases over time, and frequent reprogramming appears to be necessary.

Parkinson's and Alzheimer's: new tools, new attitudes in patient care.

In 1946, the differential diagnosis of cognitive failure resided in the hands of psychiatrists. Not until the late 1960s was permanent doubt cast on the arteriosclerotic origins of dementia. Neuro-diagnostic studies 50 years ago were limited to skull x-rays. Many neurologic signs that would now be considered indicative of Parkinson's disease (PD) were thought in 1946 to typify old age. The diagnosis of PD was made on clinical grounds, and in that regard little has changed. For treatment of PD, textbooks then had little to offer, compared with the wide range of drug therapies available today. Unknown in the mid-1940s, the molecular biology of DNA now allows practitioners a glimpse at the highly complex and multifactorial origins of Alzheimer's disease.

Treatment of age-associated memory impairment with guanfacine.

Alpha2 adrenergic agonists have been shown to improve memory test performance in amnesic humans and aged nonhuman primates. In a group of drugs in this class that were tested for their effects on age-related memory impairments in aged monkeys, guanfacine was the most effective for improving mnemonic function at doses that were without significant side effects. These data prompted studies of guanfacine for its effect on learning and memory in persons with age-associated memory impairment (AAMI), the results of which are now reported. The data suggest that guanfacine may have modest mood-improving effects but had no significant effects on learning and memory in the subjects tested.

Noninvasive techniques for assessing the effect of environmental stressors on visual function.

Visual acuity, a standard measure of visual function, is affected by a variety of physical and toxic stressors. In anesthetized animals, the acuity may be determined by the visual-evoked potential (VEP). We compared two evoked potential methods: the steady-state VEP, elicited with a fixed stimulus, and the sweep VEP, elicited by a dynamic stimulus. The steady-state VEP is a conventional electrophysiological technique for determining acuity, although its signal-to-noise ratio declines at high spatial frequencies and introduces a source of error for acuity determinations. Moreover, it is unsuited for repeated or rapid measurements. The sweep VEP is elicited by a dynamic stimulus which sweeps through a series of spatial frequencies. Response amplitude is measured with a sensitive, synchronous filter. The sweep VEP can be completed in as little as 10 s and may be used for repeated measures. On the other hand, waveform data is lost with the sweep VEP. The two techniques yield fairly similar acuity measures, generally agreeing within a factor of two.