Juvenile Muscular Atrophy of Distal Upper Extremity (Hirayama Disease).

Abstract

This disease is characterized by initially progressive muscular weakness and wasting of the distal upper limb(s) in young people predominantly in men, followed by a spontaneous arrest within several years. This disease has been thought to be separate from motor neuron diseases, yet some authors still consider the illness a variant of motor neuron disease. However, the pathological evidence of ischemic changes in the lower cervical anterior horn should facilitate differentiation of the disorder from degenerative motor neuron disease. Recent radiological investigations proved compressive flattening of the lower cervical cord due to forward displacement of the cervical dural sac and spinal cord induced by neck flexion. These findings suggest that sustained or repeated neck flexion may cause ischemic changes in the cervical anterior horn. Application of a cervical collar to minimize neck flexion prevents progressive muscular weaknessin an early stage of the disease.

Four Cases of Classical Hirayama Disease With Different Stages of Evolution

“…Such a sensory disturbance has been well documented in literature. 1 Apart from clinical evaluation, MRI of cervical spine is a must to rule out other diagnosis and to prove Hirayama disease. All of our patients satisfy MRI diagnostic criteria (table 2) for Hirayama.…”

“…Hirayama disease is characterized by progressive muscle wasting and weakness of the distal upper limb especially small muscles of hand(s) predominantly in young males, followed by spontaneous arrest within several years and it was thought to be a form of degenerative anterior horn cell disease 1 . With the advent of magnetic resonance imaging (MRI), compressive flattening of the lower cervical cord due to forward displacement of the cervical dural sac during neck flexion in these patients was picked-up.…”

“…With the advent of magnetic resonance imaging (MRI), compressive flattening of the lower cervical cord due to forward displacement of the cervical dural sac during neck flexion in these patients was picked-up. 1 So it was postulated that sustained or repeated neck flexion might cause atrophic changes in the cervical cord which was ultimately proved to be due to ischemic changes of anterior horn cells by post-mortem pathological examination. 2 During puberty there is a sudden spurt in growth of bony vertebral column compared to dura in these patients resulting in short length of dura which become tighter on neck flexion and ultimately detached from its loose posterior attachment with pedicle 3 .…”

A case of Hirayama disease treated with laminectomy and duraplasty without spinal fusion

“…Some authors consider that JADUE is not a flexion-induced cervical myelopathy, but an intrinsic motor neuron disease. The physiopathological influence of the flexion mechanism could support the effectiveness of the spinal fixation but, the natural history of the disease, which may arrest spontaneously several years after the onset 4 , questions the benefit to the surgical procedure. However, after seeing the MRI findings in our and other cases, it is difficult to reject that dural compression accompanying flexion movements represents an actual insult to spinal cord.…”

“…Juvenile amyotrophy of distal upper extremity (JADUE), also known as Hirayama disease, is characterized by 1) muscular atrophy that appears predominantly in males 15-25 years old; 2) usually sporadic, though rarely familial, occurrence; 3) limited muscular atrophy from the hand to forearm, excepting for the brachioradialis, which shows oblique amyotrophy over the forearm; 4) a lack of definite sensory disturbance and abnormal deep tendon reflex; and 5) a slowly progressive clinical course 4,10 . Since neck flexion has been thought to be the cause of the spinal cord damage, cervical orthosis, spinal fusion by an anterior or posterior approach and duraplasty in com- bination with posterior spinal fusion have been proposed as treatment of JADUE 7 .…”