Ann Rehabil Med.  2019 Oct;43(5):615-620. 10.5535/arm.2019.43.5.615.

Significance of Sufficient Neck Flexion During Magnetic Resonance Imaging in the Diagnosis of Hirayama Disease: Report of Two Cases

Affiliations
  • 1Department of Rehabilitation Medicine, Dongsan Medical Center, Keimyung University School of Medicine, Daegu, Korea. ripheonix@dsmc.or.kr
  • 2Department of Physical and Rehabilitation Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.

Abstract

It is difficult to distinguish Hirayama disease (HD) from other mimicking disorders in adolescent patients with distal upper limb weakness. The prevailing theory of HD postulates that the lower cervical cord is susceptible to compression during neck flexion because of insufficient growth of the dura relative to the spinal column. Confirmation of a dynamic change in the dorsal epidural space on magnetic resonance imaging (MRI) during neck flexion is essential for diagnosing HD. However, neck flexion MRI has not been routinely performed in juvenile patients with distal upper limb weakness in the absence of suspected HD. We report two cases of HD that were initially confused with other diseases because of insufficient or absent cervical flexion during MRI. Full-flexion MRI showed typical findings of HD in both cases. Our cases suggest that dynamic cervical MRI in the fully flexed position is necessary for evaluating suspected HD.

Keyword

Monomelic amyotrophy; Myelopathy; Magnetic resonance imaging

MeSH Terms

Adolescent
Cervical Cord
Diagnosis*
Epidural Space
Humans
Magnetic Resonance Imaging*
Neck*
Spinal Cord Diseases
Spine
Upper Extremity

Figure

  • Fig. 1. (A, B) T2-weighted cervical magnetic resonance imaging (MRI) in the neutral position revealed no signal change or spinal cord atrophy. (C, D) Contrast-enhanced MRI in the suboptimal neck-flexion position did not show dural detachment from the adjacent lamina. (E) Sagittal contrast-enhanced MRI in the fully flexed position demonstrated a crescent-shaped enlarged posterior epidural space (arrow). (F) Axial contrast-enhanced MRI in the fully flexed position revealed right dural sac detachment from the lamina and spinal cord compression by the engorged posterior epidural venous plexus (arrow).

  • Fig. 2. Upper-arm magnetic resonance imaging revealed hyperintensity and swelling of the median (asterisk) and ulnar (arrow) nerves in the axial T2-weighted fat-suppressed turbo spin-echo sequence image.

  • Fig. 3. (A) Cervical magnetic resonance imaging (MRI) in the neutral position showed disc protrusion at C5-6 and C6-7 in the sagittal T2-weighted image. (B) Cervical MRI with neck flexion revealed suspected dural detachment from the lamina (arrow). (C) Cervical MRI with full flexion demonstrated obvious widening of the dorsal epidural space with flattening of the cervical cord (arrow).


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