Waterskier’s Hirayama syndrome

Abstract

Hirayama disease is a segmental inferior cervical myelopathy. Presentation is usually in young males with unilateral or asymmetrical upper limb weakness and atrophy. The clinical features can be similar to the initial presentation of amyotrophic lateral sclerosis, but Hirayama syndrome has a benign course and is typically limited to distal muscles of the upper limbs. The typical teenage onset of the syndrome corresponds with juvenile growth spurt. The disproportionate growth of the vertebral column compared to the spinal cord resulting in the relative shortening of the dorsal roots and the loss of attachment between the posterior dural sac and the subjacent lamina are considered to be contributing factors [1]. Several reports document antecedent events including repetitive movements, competitive sport or strenuous physical work. Jeannet et al. [2] documented the case of a 10-year-old girl who had a nocturnal rhythmic movement disorder, leading to prolonged repetitive neck flexion at night time. Huang et al. [3] reported that 37.5% of their patients with Hirayama disease frequently participated in vigorous sports or physical activity for at least 6 months before the onset of symptoms. These activities included basketball, baseball, martial arts, body-building, strenuous farm work or military training. We describe the case of a competitive waterskier who presented with the typical clinical features of Hirayama syndrome. A 55-year-old international waterski champion presented with a 2-year history of progressive left hand weakness. His symptoms developed following an intensive season of waterskiing. His waterskiing activities include travelling up to speeds of 80 kph prior to jumps, with violent passive neck flexion when landing. On examination he had marked wasting of C8 and T1 innervated muscles with striking preservation of the proximal forearm musculature (Fig. 1). Sensory examination was normal as was remainder of his neurological examination. Concentric needle EMG examination revealed fibrillation potentials and positive sharp waves in the left dorsal interosseous and abductor pollicis brevis. Large amplitude long duration polyphasic motor unit activation potentials with reduced recruitment were present in the remaining C7-T1 innervated muscles on the left. Sensory nerve action potentials were normal. No abnormalities were detected in the remaining limbs. A priority of the diagnostic work up was to rule out multifocal motor neuropathy (MMN). There was no evidence of conduction block on repeated conduction studies and anti GM1 ganglioside antibody titers were negative. CSF examination was normal. Standard, axial and sagittal cervical spine MR imaging in a neutral position showed moderate spondylotic changes, in which the vertebral bodies formed an uneven posterior surface. There was no evidence of cord or nerve root compression. Axial imaging in neck flexion demonstrated cord flattening with marked anterior shifting of the posterior wall of the cervical dural canal Fig. 2. P. Bede (&) A. L. W. Bokde S. C. Byrne M. Elamin O. Hardiman Trinity College Dublin, Dublin, Ireland e-mail: bedepeter@hotmail.com