Brachioradialis Involvement in Hirayama's Disease: An Atypical Presentation of a Rare Cervical Myelopathy.

Juvenile monomelic amyotrophy (JMA), also known as Hirayama's disease, is a rare cervical myelopathy that predominantly affects young Asian males. It is characterized by degeneration of anterior horn cells due to compression by the redundant dural sac. This study presents an atypical case of a 23-year-old Indian male who exhibited uncommon symptoms of JMA. The patient displayed progressive weakness and atrophy in the left forearm, including the usually spared brachioradialis muscle. Electrophysiological tests and MRI scans solidified the diagnosis of Hirayama's disease. After wearing a cervical collar for one year, the patient's condition stabilized, reinforcing the diagnosis. Unlike most JMA cases, this instance highlights the involvement of the brachioradialis muscle, underlining the variability in JMA presentations. A precise diagnosis is contingent upon clinical criteria, dynamic MRI, and electrophysiological findings. Recognizing these variations is crucial for early detection and appropriate management of the disease.

Application of Antibodies to Neuronally Expressed Nogo-A Increases Neuronal Survival and Neurite Outgrowth.

Nogo-A, a glycoprotein expressed in oligodendrocytes and central nervous system myelin, inhibits regeneration after injury. Antibodies against Nogo-A neutralize this inhibitory activity, improve locomotor recovery in spinal cord-injured adult mammals, and promote regrowth/sprouting/saving of damaged axons beyond the lesion site. Nogo-A is also expressed by neurons. Complete ablation of Nogo-A in all cell types expressing it has been found to lead to recovery in some studies but not in others. Neuronal ablation of Nogo-A reduces axonal regrowth after injury. In view of these findings, we hypothesized that, in addition to neutralizing Nogo-A in oligodendrocytes and myelin, Nogo-A antibodies may act directly on neuronal Nogo-A to trigger neurite outgrowth and neuronal survival. Here, we show that polyclonal and monoclonal antibodies against Nogo-A enhance neurite growth and survival of cultured cerebellar granule neurons and increase expression of the neurite outgrowth-promoting L1 cell adhesion molecule and polysialic acid. Application of inhibitors of signal transducing molecules, such as c-src, c-fyn, protein kinase A, and casein kinase II reduce antibody-triggered neurite outgrowth. These observations indicate that the recovery-promoting functions of antibodies against Nogo-A may not only be due to neutralizing Nogo-A in oligodendrocytes and myelin, but also to their interactions with Nogo-A on neurons.