Remission of Severe Restless Legs Syndrome and Periodic Limb Movements in Sleep after Bilateral Excision of Multiple Foot Neuromas: A Case Report

Ludwig A Lettau; Charles J Gudas; Thomas D Kaelin

Disclosures

J Med Case Reports. 2010;4(306) 

In This Article

Abstract and Introduction

Abstract

Introduction: Restless legs syndrome is a sensorimotor neurological disorder characterized by an urge to move the legs in response to uncomfortable leg sensations. While asleep, 70 to 90 percent of patients with restless legs syndrome have periodic limb movements in sleep. Frequent periodic limb movements in sleep and related brain arousals as documented by polysomnography are associated with poorer quality of sleep and daytime fatigue. Restless legs syndrome in middle age is sometimes associated with neuropathic foot dysesthesias. The causes of restless legs syndrome and periodic limb movements in sleep are unknown, but the sensorimotor symptoms are hypothesized to originate in the central nervous system. We have previously determined that bilateral forefoot digital nerve impingement masses (neuromas) may be a cause of both neuropathic foot dysesthesias and the leg restlessness of restless legs syndrome. To the best of our knowledge, this case is the first report of bilateral foot neuromas as a cause of periodic limb movements in sleep.
Case presentation: A 42-year-old Caucasian woman with severe restless legs syndrome and periodic limb movements in sleep and bilateral neuropathic foot dysesthesias was diagnosed as having neuromas in the second, third, and fourth metatarsal head interspaces of both feet. The third interspace neuromas represented regrowth (or 'stump') neuromas that had developed since bilateral third interspace neuroma excision five years earlier. Because intensive conservative treatments including repeated neuroma injections and various restless legs syndrome medications had failed, radical surgery was recommended. All six neuromas were excised. Leg restlessness, foot dysesthesias and subjective sleep quality improved immediately. Assessment after 18 days showed an 84 to 100 percent reduction of visual analog scale scores for specific dysesthesias and marked reductions of pre-operative scores of the Pittsburgh sleep quality index, fatigue severity scale, and the international restless legs syndrome rating scale (36 to 4). Polysomnography six weeks post-operatively showed improved sleep efficiency, a marked increase in rapid eye movement sleep, and marked reductions in hourly rates of both periodic limb movements in sleep with arousal (135.3 to 3.3) and spontaneous arousals (17.3 to 0).
Conclusion: The immediate and near complete remission of symptoms, the histopathology of the excised tissues, and the marked improvement in polysomnographic parameters documented six weeks after surgery together indicate that this patient's severe restless legs syndrome and periodic limb movements in sleep was of peripheral nerve (foot neuroma) origin. Further study of foot neuromas as a source of periodic limb movements in sleep and as a cause of sleep dysfunction in patients with or without concomitant restless legs syndrome, is warranted.

Introduction

Restless legs syndrome (RLS) is a sensorimotor neurological disorder characterized by an urge to move the legs in response to uncomfortable leg sensations.[1] While asleep, 70% to 90% of patients with RLS have periodic limb movements of sleep (PLMS). Frequent PLMS and related brain arousals as documented by polysomnography are associated with poorer quality of sleep and daytime fatigue. RLS onset in middle age (late onset RLS) is sometimes associated with neuropathic foot dysesthesias (numbness, burning and/or tingling, lancinating electric shock pains, and hypersensitivity), which are attributed to small fiber-type peripheral neuropathies.[2] We have previously reported a case series of patients with diabetes or human immunodeficiency virus (HIV) whose dysesthesias of the feet were due to bilateral Morton's neuromas rather than neuropathy.[3]

A neuroma is a focal enlargement of the second, third (Morton's), or fourth digital nerve in the forefoot where each nerve stretches under the deep transverse ligament between the respective adjacent metatarsal heads.[4] Repeated nerve stress results in pathological changes of so-called entrapment neuropathy, including thickening and degenerative enlargement of the nerve and surrounding fibrous sheath into a nerve impingement mass.[5] Early symptoms include forefoot numbness and aching while late symptoms are mainly neuropathic dysesthesias. Diagnosis is primarily symptom based plus physical findings of either metatarsal head interspace tenderness or the Mulder click sign.[4,6] Interventional treatment consists of injections of local anesthetic mixed with either corticosteroids or 4% alcohol administered into the neuroma-containing interspace. If symptoms are severe and persistent or recurrent, neuroma excision is usually curative unless complicated by nerve regrowth and re-entrapment (stump neuroma).

When several of our patients reported both decreased RLS-type leg restlessness and improved quality of sleep after receipt of bilateral neuroma injections for neuropathic foot pains, their observations were considered potentially significant because of the known association of late onset RLS with neuropathic foot symptoms. This prompted a study of neuroma treatment in patients with RLS, including some without foot complaints. Of 15 patients with moderate to severe RLS, all of whom had bilateral physical findings of neuromas, treatment with injections or surgery resulted in sustained remission of RLS in nine with a concomitant marked improvement in subjective sleep quality and fatigue, indicating that their RLS was of peripheral (neuroma) origin.[7] In the current report, we describe a patient with severe, refractory RLS and PLMS with brain arousals (documented by polysomnography), the remission of which was prompt and near complete after bilateral excision of multiple foot neuromas.

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