Neuroimage: the crescent moon sign of Hirayama disease

Brain imaging inspired by outer space

Medicine has many vividly named signs. We have compiled a list of radiological cerebral signs inspired by phenomena in outer space. These range from the well-known 'starry sky' appearance of neurocysticercosis or tuberculomas, to various lesser known signs including the 'starfield' pattern of fat embolism; 'sunburst' sign of meningiomas; 'eclipse' sign of neurosarcoidosis; 'comet tail' sign of cerebral metastases; 'Milky Way' sign of progressive multifocal leukoencephalopathy; 'satellite' and 'black hole' sign of intracranial haemorrhage; 'crescent' sign of arterial dissection and 'crescent moon' sign of Hirayama disease.

Magnetic resonance imaging features of "Proximal" hirayama disease: Case report and literature review

Background:

Proximal “Hirayama” disease (PHD) is characterized by proximal upper extremity atrophy. It is a rare variant of Hirayama disease (HD) which involves the proximal upper limb. Recognition of PHD’s unique magnetic resonance (MR) findings is critical as the treatment options differ versus classical HD.

Case Description:

A 17-year-old male presented with gradual progressive upper extremity weakness and atrophy. On MR, PHD was demonstrated by C4-C5 kyphosis with a posterior epidural soft-tissue mass compressing the C4-C5 cord resulting in gliosis. As the patient declined surgery, he was followed for 1 year with a cervical collar during which time his deficit stabilized.

Conclusion:

PHD, characterized by proximal upper extremity weakness and atrophy, has characteristic MR findings of kyphosis associated with cord compression and ischemia/gliosis. Select patients as the one we described who decline surgery may stabilize radiographically and clinically with the protracted utilization of a cervical collar.