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‘Painful legs moving toes’ syndrome causes intractable pain

NEW YORK (Reuters Health) – A large case series from a neurology referral center has shed some light on a rare and mysterious movement disorder that causes debilitating pain.

“Painful legs moving toes (or ‘painful arms moving fingers’) is a rare syndrome that arises from multiple possible triggers/underlying causes,” Dr. Anhar Hassan from Mayo Clinic, Rochester, Minnesota told Reuters Health in an email. “It is disabling due to the predominant pain which is difficult to treat.”

Dr. Hassan and colleagues treated 76 patients with “painful legs moving toes” syndrome (PLMT) over the course of 20 years. They reported their experience online April 9th in Archives of Neurology.

Two thirds of the patients were women. The mean age at onset was 58 years. Pain was present at diagnosis in 70 cases and was more distressing than movements in all but one case.

Movements tended to be constant, to wax and wane in severity, and to be stereotypical in a particular individual.

The most common identifiable causes of pain were peripheral neuropathy (in 21 patients, or 28%), followed by limb trauma (eight patients, 11%) and radiculopathy (11%).

Neuroimaging of the brain and spinal cord were normal in the 44 patients evaluated, but nerve conduction studies were mildly abnormal in 30 of 63 patients. Electromyography findings included irregular phasic bursts of varying duration associated with contraction and correlating with digit or distal limb movements.

Pain treatment was generally unsuccessful, including surgical intervention in five patients. Localized therapy and physical therapies helped a few patients.

Movements were attenuated by treatment with clonazepam, pramipexole dihydrochloride, or ropinirole hydrochloride in a few cases, but without pain relief.

The syndrome persisted in 63 patients (83%) during the mean follow-up time of 4.6 years. Symptoms improved in only seven patients.

Overall, only a third of patients responded to pharmacologic treatment for movements or pain, and no factors could be correlated with response or clinical course.

“We think that ‘painful legs moving toes’ arises from a problem in the spinal cord or higher central nervous system wiring that generates both toe/foot movements and pain, that is unfortunately quite difficult to treat,” Dr. Hassan said.

“Further neurophysiology studies (somatosensory evoked potentials and motor evoked potentials), and perhaps higher resolution imaging (diffusion tensor imaging, tractography) could potentially localize the site of dysfunction,” he said. “Functional neuroimaging could also determine whether an abnormal neural network is activated in this disorder.”

“Prior to treating the pain, it is important to have a neurologist take a history and examine the patient to exclude an alternate cause of pain,” Dr. Hassan concluded. “If the pain is attributed to ‘painful legs moving toes’, then a neuropathic pain medication/anticonvulsant may be helpful (gabapentin, pregabalin, carbamazepine) or tricyclic antidepressant (amitriptyline) or non-opioid analgesic (tramadol) may be tried. The response rate appears to be less than 50%, so more than one agent may need to be titrated up to achieve a response.”

Finally, he added, “It is important to exclude dystonia, hyperexcitable nerve problems, and other pain conditions.”

SOURCE: http://bit.ly/J0b6Jl

Arch Neurol 2012.