Reply: Sensory profile in primary restless legs syndrome and restless legs syndrome associated with small fibre neuropathy

Abstract

Sir, We wish to thank the editor for giving us the opportunity to respond to this letter. We appreciated reading that Drs Gemignani and Vitetta think our study (Bachmann et al. , 2010) provides support for the differential diagnosis of primary and secondary restless legs syndrome (RLS) associated with small fibre neuropathy, when comparing the sensory profiles of these groups of patients for the first time. Dr Gemignani recently wrote ‘A general consensus on the proposed criteria for the diagnosis of small fibre neuropathy has not been established’ (Gemignani, 2010 b ). This already applies for small fibre neuropathy without complicating RLS; however, for the constellation of RLS with small fibre neuropathy a general consensus is even further from being reached. Though the association of RLS and small fibre neuropathy may still be controversial, in primary RLS comorbidity is most likely coincidental and not causal, whereas in secondary RLS associated with small fibre neuropathy it may be different. Gemignani and Vitetta express their concerns regarding the classification of secondary RLS associated with small fibre neuropathy based mainly on the requirement of pain. The authors address the principle problem that no single feature can provide a 100% differentiation. Of course, tingling and dragging paraesthesias may also be a feature of small fibre neuropathy. The notion of paraesthesias as a symptom of small fibre neuropathy is in accordance with our text, as we clearly pointed out ‘Some of the more overt clinical features of patients with small fibre neuropathy are burning or shooting pain, paraesthesias and numbness (Hoitsma et al ., 2004; Ho et al ., 2009)’. However, by requiring spontaneous pain for the secondary RLS group, we narrowed possible patients for inclusion in order to be certain that only patients with secondary RLS with small fibre neuropathy were included in this …