"While Hirayama disease is predominantly sporadic, rare familial cases have been linked to genetic variants, specifically the KIAA1377 (CEP126) gene and the C5orf42 locus 8."
"abnormal T2-weighted signal of the spinal cord with asymmetric atrophy/flattening at typically C5-C7"
"at the site of maximal forward shift of the posterior dural sac, the spinal cord is dynamically compressed with a reduction in the AP diameter of the cord compared to neutral imaging 6"
"Hirayama disease is usually of insidious onset, presenting with predominantly unilateral upper-extremity weakness and atrophy, cold paresis, hyperhidrosis, minipolymyoclonus, and no sensory or pyramidal tract involvement 8,9. The weakness and atrophy typically spares the brachioradialis whilst affecting other muscles of the forearm and hand, giving the characteristic appearance of oblique amyotrophy that affects the C7, C8 and T1 myotomes 5,6. The amyotrophy is unilateral in most patients, asymmetrically bilateral in some, and rarely symmetric 5. Limb symptoms usually progress gradually over several years 8."
"Hirayama disease is usually of insidious onset, presenting with predominantly unilateral upper-extremity weakness and atrophy, cold paresis, hyperhidrosis, minipolymyoclonus, and no sensory or pyramidal tract involvement 8,9. The weakness and atrophy typically spares the brachioradialis whilst affecting other muscles of the forearm and hand, giving the characteristic appearance of oblique amyotrophy that affects the C7, C8 and T1 myotomes 5,6. The amyotrophy is unilateral in most patients, asymmetrically bilateral in some, and rarely symmetric 5. Limb symptoms usually progress gradually over several years 8."