Atopic myelitis with focal amyotrophy: a possible link to Hopkins syndrome

Abstract

Among 22 consecutive patients with myelitis, of unknown etiology, and atopic diathesis (atopic myelitis) who from April 2002 to March 2006 had been studied in our clinic, 5 (23%) showed focal amyotrophy in one or two limbs. These 5 patients were subjected to combined clinical, electrophysiological, neuroimaging and immunological studies. Ages were 18 to 58-years-old (average 39). Four showed amyotrophy of unilateral or bilateral upper limbs while one showed amyotrophy in both thighs. All patients showed on-going denervation potentials in the affected muscles, while motor conduction study including F wave was normal except for in one patient who showed prolonged F wave latency in one nerve. Two had localized high signal intensity lesions involving anterior horns on spinal cord MRI and three showed abnormalities suggesting pyramidal tract involvement on motor evoked potentials. All had a present and/or past history of atopic disorders and specific IgE against common environmental allergens, such as mite antigens and cedar pollens, and four showed mild eosinophilia, all of which were compatible with atopic myelitis. When clinical and laboratory findings were compared between atopic myelitis with (n=5) or without focal amyotrophy (n=17), the former showed a significantly higher frequency of present and past history of asthma (80% vs. 24%, p=0.0393) and tended to have higher EDSS scores (3.8+/-1.6 vs. 3.1+/-1.4). Two patients showed mild to moderate improvements after immunotherapies such as methylprednisolone pulse therapy or plasma exchange, while two recovered with low dose corticosteroids and one without treatment had a gradually progressive course. Although atopic myelitis preferentially involves the posterior column of the cervical spinal cord, it is possible that anterior horn cells are affected in some cases of atopic myelitis, especially in patients with asthma. This suggests a possible link between atopic myelitis and Hopkins syndrome (asthmatic amyotrophy).