Few good treatments for orthostatic tremor

By Will Boggs MD

NEW YORK (Reuters Health) - Orthostatic tremor is a rare, progressive condition with largely unsatisfactory drug treatment options, though surgery may hold some promise, according to a new report.

"Clinicians should be aware that orthostatic tremor (OT) is and remains largely an isolated condition both on clinical and electrophysiological grounds," Dr. Christos Ganos from UCL Institute of Neurology in London, UK, told Reuters Health by email. "Among the minority of patients who exhibit additional neurological symptoms, non-parkinsonian motor slowness and gait dysfunction are the most common and are probably related to symptom compensation."

OT is marked by high-frequency tremor (13-18 Hz) that develops upon standing and primarily affects the legs and trunks, Dr. Ganos and colleagues write in the Journal of Neurology, Neurosurgery and Psychiatry, online March 13. Little is known about its natural progression.

The team studied the long-term outcome of 68 patients with OT who were followed for at least five years (median, 6 years; range, 5-25 years). Median symptom duration was 14 years (range, 5-50 years).

Two-thirds of the patients were women, and 87% presented with isolated OT. Fifty-four patients reported worsening of their OT symptoms over time.

Clonazepam (used by 38 patients) and gabapentin (used by 24) were the most common treatments, with only 35 patients (51.5%) reporting some benefit from trials of medications. Overall, though, the responses were disappointing, inconsistent, and complicated by nonspecific side effects.

Still, most patients remained on some medication at last follow-up. The researchers say the patients felt that, in the long term, "something was better than nothing."

One patient experienced some benefits from a spinal cord stimulator, and another from bilateral deep brain stimulation of the ventralis intermedius nucleus of the thalamus.

"Based on our data clinicians should inform their patients that OT is and will remain largely an isolated condition on the long term (i.e. patients will most likely not develop other disorders, such as Parkinson's disease or cerebellar ataxia)," Dr. Ganos said. "In severe cases, there are further promising options, such as deep brain stimulation, but evaluation as to suitability for surgery and the surgical procedure itself need to be performed only in large centers with long expertise on movement disorders and good interdisciplinary work between neurology and neurosurgery. Also, the long-term efficacy of invasive methods needs to be addressed in future studies."

"We would like to highlight, however, that we studied patients with true orthostatic tremor (i.e., with a highly coherent tremor between homologous muscles of right and left leg, and frequency in the 13-18 Hz range)," Dr. Ganos added. "Clinicians should also be aware of cases with orthostatism but not true orthostatic tremor, such as orthostatic myoclonus for example, where different medications could be more helpful, or patients with orthostatism as part of a different disorder, as for example in cases with slow orthostatic tremor (< 10 Hz) due to parkinsonian conditions, which may improve with dopaminergic treatment."

Dr. Kenneth M. Heilman from the University of Florida College of Medicine in Gainesville told Reuters Health, "The patients who I treated with (clonazepam) and who had a reduction of symptoms found that this medication worked after the first few doses. Thus, after several days if there is no response I try another medication. Often when patients start this medication they do have the side effects often associated with benzodiazepines including drowsiness, but with repeated use of this medication these side effects often subside."

"I tell my patients that while this is a disabling disorder, and may over time get worse, that most of my patients' thinking and reasoning remains intact and that most patients can still take care of themselves and even perform many activities," Dr. Heilman, who was not involved in the study, said in an email. "I also do mention to my patients that they may have a slightly greater risk of developing other neurological disorders."

"While most reports do state that this is a rare disorder, it may be rare because physicians are unaware of it," Dr. Heilman said. "Since many patients can benefit from treatment, it is important that they be aware of this disorder."

Dr. Francesco Raudino, who also was not involved in the study, recently reported on the SPECT findings in one 59-year-old man with OT.

"In my opinion the benzodiazepines are quite effective," Dr. Raudino, from "Valduce" Hospital in Como, Italy, told Reuters Health by email. "I don't know if they act directly on it or because they reduce anxiety. Usually their effectiveness is manifest in a few days, so a two-week trial is adequate."

He added, "The main message for physicians is that they (should not) mistake orthostatic tremor with Parkinson's disease (in my experience this happened only once) and that the prognosis is relatively good."

SOURCE: http://bit.ly/1MaUSU9

J Neurol Neurosurg Psychiatry 2015.

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