Morphological changes of the lower cervical spinal cord under neutral and fully flexed position by MRI in Chinese patients with Hirayama's disease

Abstract

We examined MR images of the spinal cord from the neutral neck to the fully flexed neck position in Chinese patients with Hirayama's disease (HD). MRI was performed on 25 HD patients and 31 healthy controls in the neutral and fully flexed neck positions. The mean anterior-posterior diameter (APD) and transverse diameter (TD) of the cervical cord at C6 level in the different positions was measured. Localized lower cervical cord atrophy and asymmetric cord flattening in a neutral neck position were highly suggestive of HD. The mean APDs were 5.6+/-0.7 mm in HD patients and 6.7+/-0.5 mm in controls (p <0.001). These changes seemed related to longer disease duration, i.e. >18 months. Although displacement forward of the lower cervical spinal cord without significant compression was observed in healthy young people, anterior shifting of posterior dural sac and lower cervical cord compression in flexion were distinctive and pathognomonic features of HD. The mean APDs were 4.3+/-0.9 mm in HD patients and 6.0+/-0.5 mm in controls in flexion (p <0.001). Our results may be helpful in diagnosing and assessing this disease.

Hirayama’s disease: an Italian single center experience and review of the literature

“…Some authors (31,33,34) reported the presence of forward shifting of the dural sac in all their patients. Nevertheless this sign is not always present in HD patients.…”

“…Two of our patients (25%) showed T2 hyperintensities of the spinal cord respectively at C5-C6 and C6-C7 levels. High signal alterations on T2 weighted images without cord compression are described in the literature, but this finding is inconstant, presenting in about one third or less of the patients (10,27,34,42).…”

Mutational analysis of glycyl-tRNA synthetase (GARS) gene in Hirayama disease

“…The disease affects mainly young males and after progressing for a few years it generally stabilizes and remains confined to the upper limbs (1). In many cases HD is associated with lower cervical cord atrophy and asymmetric cord flattening (2, 3). Concerning its etiology, some authors suggested mechanical compression of the lower cervical spine during flexion, but this pathogenic mechanism is not unanimously accepted (1–5).…”

Mutational analysis of glycyl-tRNA synthetase (GARS) gene in Hirayama disease

“…The disease affects mainly young males and after progressing for a few years it generally stabilizes and remains confined to the upper limbs (1). In many cases HD is associated with lower cervical cord atrophy and asymmetric cord flattening (2,3). Concerning its etiology, some authors suggested mechanical compression of the lower cervical spine during flexion, but this pathogenic mechanism is not unanimously accepted (1)(2)(3)(4)(5).…”

“…In many cases HD is associated with lower cervical cord atrophy and asymmetric cord flattening (2,3). Concerning its etiology, some authors suggested mechanical compression of the lower cervical spine during flexion, but this pathogenic mechanism is not unanimously accepted (1)(2)(3)(4)(5). Others consider HD as a segmental form of spinal muscular atrophy (6).…”