Hirayama disease: Nosological classification and neuroimaging clues for diagnosis

Abstract

Hirayama disease (HD) is a rare, benign, and nonprogressive motor neuron disease (MND) affecting the upper limbs. It usually presents with weakness and amyotrophy in a single upper extremity with an insidious onset between adolescence and the third decade of life. Since its description in 1959, HD has been known under several names and eponyms in Europe and in Asian countries probably due to its heterogeneous clinical features.Thus, the unclear nosological classification makes challenging the differential diagnosis between HD and other neuromuscular conditions, such as MNDs. However, apart from the nosological difficulties and the lack of evidence-based guideline for diagnosis, the neuroimaging is the mainstay for the diagnosis of HD. Indeed, the specific findings on cervical flexion MRI usually lead to a prompt diagnosis. Here, we reviewed the nosological classifications of HD and its neuroimaging features. Also, we report a case of a 18-year-old boy who presented to our Clinic complaining of muscle weakness of the left distal upper limb without other neurological signs. The cervical MRI, in the neutral position, revealed a high T2 signal intensity in the C5-C7 cervical myelomeres as well as the loss of cervical lordosis, whereas, during neck flexion, it showed the anterior displacement of the posterior dura ad the post-gadolinium T1-weighted imaging enhancement of the posterior epidural plexus. These findings are typical for HD allowing the diagnosis as well as the differential diagnosis from other neuromuscular diseases.

Characteristics of Hirayama Disease in Young South Korean Soldiers

“…Several studies have found varying degrees of cord atrophy above and below the C6 vertebral body level. 2 32 Some studies have found atrophy to be most severe at the C6–C7 level, 25 29 with others finding a higher prevalence of C5–C6 cord atrophy. 27 …”

“… 1 HD is diagnosed based on a combination of distinctive clinical features and electrodiagnostic and cervical magnetic resonance imaging (MRI) findings. 2 3 4 5 6 The clinical presentation of HD includes asymmetric oblique amyotrophy, specifically involving the distal muscles of the hand and forearm, but sparing the brachioradialis. HD primarily affects males and typically manifests during late adolescence or early adulthood.…”

A Vietnamese Case of Hirayama Disease and Narrative Review of Literature

“…[12,23,24] This could somehow explain why the clinical symptoms occurred within the cord area from C7 to T1 myotomes and the upper levels are usually spared. Hirayama postulated the "stagnation of the posterior epidural venous plexus" as contribution factor of cord compression [20] and venous engorgement also disturbed the microcirculation and aggravated the local ischemia within the cord [14]. HD affects predominantly male population, with male/ female ratio approximately 10/1.…”

Surgical management of Hirayama disease in a pediatric patient presenting with severe cervical kyphosis and focal myelopathy: illustrative case

“…[6][7][8] Magnetic resonance imaging (MRI) reveals cervical straightening or mild kyphosis, flattening of the midlower cervical cord, and a crescent-shaped posterior epidural space on T2-weighted imaging. 5,9 Electrodiagnostic studies reveal normal or mildly impaired conduction velocities and classical sparing of the cranial, thoracic, lumbar, and sacral nerves. 1,2,10 Although often self-limited, HD has the potential to lead to progressive cervical myelopathy and concomitant disability.…”