[Restless legs syndrome in Fabry disease: clinical feature associated to neuropathic pain is overlooked].

INTRODUCTION: Neuropathic pain (NP) is a main feature of Fabry disease (FD) as consequence of small fiber neuropathy. Restless legs syndrome (RLS) in FD was not described, but it is an important feature in other small fiber neuropathies, i.e., diabetes. The aim of this study was to assess the prevalence of RLS in patients with FD, and its association with neuropathy.

PATIENTS AND METHODS: We investigated the occurrence of RLS in four families of classical FD, diagnosed in accordance with the criteria of the International RLS Study Group. Eleven patients, 6 hemicigote and 5 heterocigote, ages among 19 to 32 years old for males and 45 to 56 years old for females, were studied. The 6 hemizigote and 2 heterozigote patients were on enzyme therapy with agalsidase beta.

RESULTS: One heterocigote patient had not clinical NP and the other 10 patients had small fiber sensory neuropathy with symptoms: burning and painful feet. RLS was present in 3/6 hemicigote and 1/5 heterocigote patients (36%). In these four patients, RLS was associated with dysesthesias or pain crisis and it was characterized to be a desire to move the low extremities as crisis of motor restlessness. RLS was characterized for worsening of symptoms with rest without diurnal changes. Patients have to uncover the feet for improving burning or sometimes they have to get out of bed in the night looking for relief. Both NP and RLS improved after 3 years of enzyme replacement therapy.

CONCLUSIONS: Our data shows that RLS is associated to NP as a treatable manifestation of small fiber involvement in the course of FD.