2 Walton Centre NHS Foundation Trust, Liverpool, United Kingdom 3 National Hospital for Neurology and Neurosurgery, London, United Kingdom 1. Nobile-Orazio E, Gallia F, Tuccillo F, Terenghi F. Chronic inflammatory demyelinating polyradiculoneuropathy and multifo- cal motor neuropathy: treatment update. Curr Opin Neurol 2010;23:519–523. 2. Boukhris S, Magy L, Khalil M, Sindou P, Vallat JM. Pain as the pre- senting symptom of chronic inflammatory demyelinating polyradicu- loneuropathy (CIDP). J Neurol Sci 2007;254:33–38. 3. Tan G, Jensen MP, Thornby JI, Shanti BF. Validation of the Brief Pain Inventory for chronic nonmalignant pain. J Pain 2004;5: 133–137. 4. Singleton JR. Evaluation and treatment of painful peripheral poly- neuropathy. Semin Neurol 2005;25:185–195. 5. Dworkin RH, O’Connor AB, Backonja M, Farrar JT, Finnerup NB, Jensen TS, et al. Pharmacologic management of neuropathic pain: evidence-based recommendations. Pain 2007;132:237–251. Published online 24 February 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/mus.23355 --------------------------------------------------------- CHARACTERIZATION OF NON–LENGTH-DEPENDENT SMALL-FIBER SENSORY NEUROPATHY In their recent work, Khan and Zhou reported the larg- est series to date of non–length-dependent small-fiber sensory neuropathy (NLD-SFSN). 1 This is a less well-rec- ognized and characterized form of SFSN, which can be mistaken for a somatization disorder due to its unusual presentation and the lack of awareness of its status as a distinct disorder. Their useful study may help make this underdiagnosed condition more easily recognizable, because the clinical features are now better delineated. With respect to the clas- sical, length-dependent form of SFSN, 2 patients were younger, predominantly women, and more often had asso- ciated immune-mediated conditions, confirming in part what was suggested in previously reported small series. 3,4 The peculiar distribution of sensory symptoms and signs suggests that NLD-SFSN is most likely a ganglion- opathy, which is selective for small-diameter dorsal root ganglion (DRG) sensory neurons. 3,5 This hypothesis is strengthened by the notion that associated conditions in NLD-SFSN are quite different from those that underlie axonal damage in distal SFSN. With segregation of LD- SFSN and NLD-SFSN into distinct entities by site of lesion and etiology, one would expect to observe some- what different symptoms to arise in distal axons or DRG sensory neurons. Further, it has been speculated that sensory symptoms and signs may translate into different mechanisms of neuropathic pain. 6 Khan and Zhou only describe NLD-SFSN symptoms as ‘‘including pain, burn- ing, tingling, and/or numbness.’’ It would be of interest to know whether the sensory symptoms of NLD-SFSN were different from those of LD-SFSN. Signs of small- fiber involvement on examination were found in 63% of NLD-SFSN patients, but a comparison with the classical SFSN group was not made. In our small series, itch seemed to be a quite characteristic symptom in NLD- SFSN, 4 whereas Khan and Zhou noted that itching did not occur their series. They correctly conclude that it was unlikely to be a prominent symptom, although possi- bly it could have been overlooked in a retrospective study. It is noteworthy, however, that a non–length-de- pendent pattern has been described in some patients with itch as the main symptom of SFSN. 7 A strength of the study was that inclusion of the patients was fairly selective and homogeneous, as inclu- sion criteria required biopsy-proven ‘‘pure’’ small-fiber involvement, whereas previous studies either included patients with large-fiber involvement 3 or those in whom the diagnosis of NLD-SFSN was made based entirely on clinical symptoms and signs. 4 However, as acknowledged by the authors, the composition in their series may have been influenced by the use of stringent criteria, as well as by referral bias. In other words, it could be that idio- pathic patients, who are more likely to undergo exten- sive investigations including skin biopsy due to the diffi- culty of making a diagnosis, were overrepresented with respect to patients who had a more obvious etiology for neuropathy. A clinically based approach for the study of neuropathic pain conditions, using tools readily available in clinical practice, has been advocated to expand the investigated population. 8 This may facilitate epidemio- logic studies of this rare, but probably overlooked condition. Because immune-mediated conditions are relatively common in NLD-SFSN (including sarcoidosis, which was successfully treated with intravenous immunoglobulin in 1 patient by Khan and Zhou), an immune-mediated pathogenesis should also be suspected in idiopathic cases and may give impetus to trials of immunodulatory treatment. Editorial Note: Drs. Khan and Zhou were offered the opportunity to comment on this letter but they declined. Franco Gemignani, MD Department of Neurosciences, University of Parma, Parma, Italy 1. Khan S, Zhou L. Characterization of non–length-dependent small- fiber sensory neuropathy. Muscle Nerve 2012;45:86–91. 2. Lacomis D. Small-fiber neuropathy. Muscle Nerve 2002;26:173–188. 3. Gorson KC, Herrmann DN, Thiagarajan R, Brannagan TH, Chin RL, Kinsella LJ, et al. Non-length dependent small fibre neuropathy/gan- glionopathy. J Neurol Neurosurg Psychiatry 2008;79:163–169. 4. Gemignani F, Giovanelli M, Vitetta F, Santilli D, Bellanova MF, Brin- dani F, et al. Non-length dependent small fiber neuropathy. a pro- spective case series. J Peripher Nerv Syst 2010;15:57–62. 5. Koike H, Sobue G. Small neurons may be preferentially affected in ganglionopathy. J Neurol Neurosurg Psychiatry 2008;79:113. 6. Woolf C. Dissecting out mechanisms responsible for neuropathic pain: implications for diagnosis and therapy. Life Sci 2004;74:2605–2610. 7. Devigili G, Tugnoli V, Quadrale R, Casetta I, Gastaldo E, Tola MR, et al. Neuro- pathic itching syndrome: a preliminary study. Eur J Pain 2007;14(suppl 1):S137. 8. Walk D, Sehgal N, Moeller-Bertram T, Wasan A, Wallace MS, Irving G, et al. Quantitative sensory testing and mapping: a review of non- automated quantitative methods for examination of the patient with neuropathic pain. Clin J Pain 2009;25:632–640. Published online 27 March 2012 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/mus.23394 --------------------------------------------------------- NERVE CONDUCTION STUDIES IN CHARCOT–MARIE–TOOTH DISEASE IN A COHORT FROM TURKEY I read the study by Deymeer et al., 1 which nicely con- firms the utility of nerve conduction studies in Letters to the Editor MUSCLE & NERVE August 2012 295