HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Correspondence to:

ARTICLES: Sunil Pradhan Bilaterally symmetric form of Hirayama disease Neurology 2009; 72: 2083-2089 [Abstract] [Full text] [PDF]

Correspondence: Submit a response to this article

Correspondence published:

Bilaterally symmetric form of Hirayama disease

Josep Gamez   (2 September 2009)

Reply from the author

Sunil Pradhan   (2 September 2009)

Bilaterally symmetric form of Hirayama disease 2 September 2009
Josep Gamez, ALS Unit, Neurology Dept., Hospital Universitari Vall d'Hebron Passeig Vall d'Hebron 119, 08035, Barcelona, SPAIN Send Correspondence to journal: Re: Bilaterally symmetric form of Hirayama disease 12784jgc{at}comb.es Josep Gamez	Pradhan reported bilateral symmetric involvement in eleven cases within a series of 106 patients with Hirayama disease (HirD). [1] The iconographic information is important for the correct diagnosis of this rare form of motor neuron disease. However, the author’s suggestion that “the symmetric involvement has never been described” is incorrect. Hirayama reported a small subset of patients with symmetric atrophy and weakness on many occasions. For example, of the 333 cases analyzed in a National Japan Survey, 3.1% presented with the variant described by Pradhan. [2] Other authors have reported similar cases. [3,4] The diagnosis of HirD variants is difficult and diagnosis criteria are supported by lab and neuroimaging tests to rule out other entities. [2] Identification of HirD has led to a search for labels that cover these clinical variants of HirD including: late onset, familial forms, proximal muscle involvement, and bilateral and progressive forms. [5] Since the first definition of this entity as “juvenile muscular atrophy of unilateral upper extremity” was coined by Hirayama in 1959, other terms have been used to improve the definition of the different clinical variants of the disease, including “chronic segmental spinal muscular atrophy of the upper extremities”, “anterior tephromalacia”, and “O’Sullivan-McLeod syndrome.” In addition to the anatomical abnormalities in the cervical/dural canal mentioned by the author, there are other pathogeneses of HirD. EMG observation of chronic denervation signs in the proximal muscles of all four limbs in at least one third of patients suggests that it may be an adult-onset diffuse lower motor neuron disease, or a clinical variant of spinal muscular atrophy with a focal symptomatology and benign course. There may also be genetic factors which play a role in the disease’s etiopathogenesis, considering the patients’ male predominance, Asian origin, and the descriptions of familial cases. References 1. Pradhan S. Bilaterally symmetric form of Hirayama disease. Neurology 2009;72:2083-2089. 2. Tashiro K, Kikuchi S, Itoyama Y, et al. Nationwide survey of juvenile atrophy of distal upper extremity (Hirayama disease) in Japan. Amyotroph Lateral Scler 2006;7:38–45. 3. Tataroglu C, Bagdatoglu C, Apaydin FD, Celikbas H, Koksel T. Hirayama's disease: a case report. Amyotroph Lateral Scler Other Motor Neuron Disord 2003;4:264-265. 4. Gaio JM, Lechevalier B, Hommel M, Viader F, Chapon F, Perret J. Chronic spinal amyotrophy involving the upper limbs in young adults (O'Sullivan and McLeod syndrome). MRI study of the cervical spinal cord. Rev Neurol (Paris). 1989;145:163-168. 5. Gamez J, Also E, Alias L, et al. Investigation of the role of SMN1 and SMN2 haploinsufficiency as a risk factor for Hirayama's disease: clinical, neurophysiological and genetic characteristics in a Spanish series of 13 patients. Clin Neurol Neurosurg 2007;109:844-848. Disclosure: The author reports no disclosures.
Reply from the author 2 September 2009
Sunil Pradhan, Professor of Neurology Sanjay Gandhi Postgraduate Institute of Medical Sciences, Raebareli Road, Lucknow, India. Send Correspondence to journal: Re: Reply from the author drspradhan{at}rediffmail.com Sunil Pradhan	I thank Dr. Gamez for his comments. Evolution of a syndrome into specific diseases repeatedly suggests that an apparently single disorder may be a group of etiologically different diseases. The initial description of "monomelic amyotrophy" included pure motor wasting of one upper and one lower limb. [6] The description of upper limb weakness and wasting was similar to Hirayama disease and that of lower limb more or less akin to what has been described from North India as "wasted leg syndrome." [7] After the demonstration of mechanovascular changes in flexion MRI of the cervical spine [8], the upper limb monomelic amyotrophy was soon considered a different disease than that of lower limb. A subsequent description of Hirayama disease was referred to as "brachial monomelic amyotrophy". [9] Hirayama disease primarily involves C7, C8 and T1 myotomes with distal upper limb wasting. Inclusion of patients with evidence of chronic denervation in proximal muscles of all four limbs as mentioned by Gamez may prompt debate on what to accept as Hirayama disease. We did not find evidence of chronic denervation in the right quadriceps and tibialis anterior muscles screened under a standard EMG protocol for upper limb diseases. Some patients with juvenile onset motor neuron disease and distal spinal muscular atrophies have focal onset, benign course, and a widespread chronic denervation on EMG. Inclusion of these and other unknown benign anterior horn cell disorders under the category of Hirayama disease may falsely convey diffuse denervation in this disorder. Several of these patients may show bilateralism. Some studies showing diffuse denervation in monomelic amyotrophy have included patients with one lower limb involvement. This may misclassify patients as having Hirayama disease. [10] The nationwide survey in Japan supports our finding of bilateralism in several patients with Hirayama disease. [2] Symmetrical involvement in some of these patients calls for the need to avoid terminologies suggesting unilateralism to denote this disorder. Our study is unique as it maintained a gold standard in the selection of patients because we included those having visible dynamic changes in flexion MRI particularly during the acute phase of illness. We do not know whether it is proper to classify other patients as having Hirayama disease but we were clear in the selection of our patient group. It is a good demonstration of symmetric and asymmetric bilateralism in patients with Hirayama disease. References 6. Gouri-Devi M, Suresh TG, Shankar SK. Monomelic amyotrophy. Arch Neurol 1984;41:388-394. 7. Prabhakar S, Chopra JS, Banerjee AK, Rana PV. Wasted leg syndrome: a clinical, electrophysiological and histopathological study. Clin Neurol Neurosurg 1981;83:19-28. 8. Pradhan S, Gupta RK. Magnetic resonance imaging in juvenile asymmetric segmental spinal muscular atrophy. J Neurol Sci 1997;146:133-138. 9. Gourie-Devi M, Nalani A. Long-term follow-up of 44 patients with brachial monomelic amyotrophy. Acta Neurol Scand 2003;107:215–220. 10. Khandelwal D, Bhatia M, Singh S, et al. Widespread electromyographic abnormalities in patients with monomelic amyotrophy: a detailed EMG study. Electromyogr Clin Neurophysiol 2005;45:63-67. Disclosure: Dr. Pradhan is an Associate Editor for Neurology India.