Hirayama Disease is a spinal muscular atrophy which presents with varying degrees of unilateral or asymmetric bilateral distal muscle weakness of the upper extremity. It is a rare, non-progressive motor neuron disease, mostly affecting young males. Although considered to have a relatively stationary clinical course after a period of initial progression, it can be functionally impairing in some patients. Here, we present a case of a 20-year-old male who complained of weakness of his right upper extremity for 1 year with difficulty performing activities of daily life. This case highlights the role of radiologist in identifying the subtle findings in cervical spine MRI of patients with such presentation. Moreover, it emphasizes the importance of including flexion imaging MRI sequences in a patient with suspicion of Hirayama disease.

Monomelic amyotrophy (MMA) is a lower motor neuron predominant disorder affecting an upper limb, which can mimic amyotrophic lateral sclerosis (ALS). It often presents with unilateral, distal upper limb weakness and atrophy, whose trajectory is one of an initial period of progression followed by a prolonged plateau, as opposed to the typically relentless progression as is seen in ALS. This case report describes a novel observation of a patient with MMA with an unexplained ipsilateral partial Horner's syndrome (miosis and ptosis). Horner's syndrome is known to result from sympathetic dysfunction from lesions from the hypothalamus to the cervical/upper thoracic spine and can be seen with brachial plexopathies, but has never been, to our knowledge, described in MMA. This finding is of interest because it may facilitate earlier diagnosis of MMA in isolated upper extremity, lower motor neuron-predominant syndromes, as Horner's syndrome is not known to complicate ALS.

Hirayama disease (HD) is a cervical flexion-induced compressive myelopathy. Typically, there is forward displacement and loss of attachment of dural sac to lamina at the cervical level during neck flexion. However, the extent of the dural detachment (DD) has not been studied carefully. We undertook this study to know the extent of DD in HD. We conducted a retrospective study of HD patients evaluated from 2015 to 2023. Patients with DD extending beyond the cervical spine were selected, and their clinical and radiological features were studied. One hundred and thirty-two (62.8%) patients were identified to have DD beyond the cervical spine in a cohort of 210 HD patients. The mean age at onset and duration were 18.09 ± 2.3 years (13-26) and 38.63 ± 39.9 months, respectively. Proximo-distal involvement was noted in 50% of patients, while 33% and 17% of patients had isolated distal and proximal involvement, respectively. Wasted legs were observed in three patients. Cord atrophy was present in 96.9% of patients, extending from C5 to C7. Epidural detachment and engorgement of posterior epidural venous plexus were evident in all. DD extended from C2 to D10 vertebral level. The cranial extent of DD was from C2 to C4 in 87% of cases, and the caudal extent was D1-D5 in 84% of cases, extending up to D10 in two cases. The HD spectrum continues to evolve phenotypically and radiologically. The pathophysiological mechanisms and DD extend beyond the cervical spine in a large proportion of patients. This makes it important to cover a longer part of the spine during imaging. This may have implications on the management of patients, particularly those with isolated lower limb involvement.

Hirayama disease (HD) is a rare, nonfamilial, monomelic amyotrophy in which patients present with muscle atrophy and weakness of the forearms and hands, either unilateral or bilateral, and without sensory loss. Current treatment guidelines describe the role of conservative treatments including cervical collars and neurotropic medications, as well as spinal surgery in select patients. Upper extremity surgery has not yet been incorporated into the treatment algorithm of HD. The objective of this study is twofold: to present a case series of HD patients treated with the incorporation of nerve and tendon transfers and joint fusions into the existing treatment algorithm and to perform a literature review of interventions. Three cases (4 limbs) of HD treated surgically with nerve and tendon transfers and fusion are retrospectively reviewed. The subjective and objective results from surgery are reported. A literature review is performed on PubMed using "Hirayama disease" and "peripheral nerve surgery," "nerve transfer," "tendon transfer," "hand surgery," or "upper extremity surgery" as search terms to identify studies describing surgical treatment of HD outside of spinal surgery. Three HD patients (4 limbs) were identified. The average age was 23 years old (range, 16-33 years). Patients presented with intrinsic muscle atrophy, hypothenar, and thenar atrophy. The disease had been present for an average of 6.5 years (range, 1.5-15 years) prior to referral. Two patients had unilateral involvement, whereas one had bilateral involvement. Two patients (3 limbs) were treated with an anterior interosseous (AIN) to ulnar motor nerve transfer, whereas a patient with delayed presentation underwent thumb metacarpophalangeal joint fusion and a Zancolli lasso to the fingers. All patients had subjective and objective improvements postoperation.The literature reveals three independent case reports of HD patients treated with upper extremity surgery. Two papers describe using a tendon transfer, whereas one paper describes an AIN to ulnar motor nerve transfer. All patients demonstrated functional improvements in follow-up. HD can be successfully treated with a combination of upper extremity surgery and nerve transfers. To the authors' knowledge, this is the first literature review and the largest case series presenting such interventions in HD.

Hirayama disease (HD) is a rare, nonfamilial, self-limiting, progressive lower cervical myelopathy, resulting in debilitating distal upper-extremity motor deficits, mimicking high ulnar neuropathy, lower trunk brachial plexopathy, or C8-T1 radiculopathy. Although most literature focuses on pathophysiology and prevention of disease progression, there remains limited discussion regarding treatment to improve upper-extremity function in patients with stable disease. The upper-extremity manifestations of HD are reviewed along with surgical options for restoring hand function. A retrospective review of patients with HD who underwent reconstruction to improve hand function was undertaken. Demographic data, preoperative electrodiagnostic and electromyographic, and physical examination findings were collected. Outcome data involved postoperative grip, pinch, and functional assessment documented on clinical visits. Qualitative descriptions of the surgical techniques are described. Among six patients identified, four met the inclusion criteria and underwent tendon transfers and selected joint arthrodeses. All patients were diagnosed as teenagers, were right hand-dominant, and three were male. Unilateral symptoms were present in one patient and were bilateral in the rest. All patients were treated with tendon transfers for thumb opposition, grasp, anticlaw, and thumb interphalangeal joint arthrodesis. All patients had postoperative grip strength improvement. The average follow-up was 3.2 years. Hirayama disease is a rare disease often managed by spine surgeons and neurologists who may be unaware of options for restoring hand function deficits. Technical strategies and outcomes of improving hand function in HD have not been adequately described. Surgical options to improve hand function are tailored to the deficits and include tendon transfers, select joint arthrodeses, and/or tenodeses. Risk of disease progression and expectations following hand reconstruction must be managed carefully. Therapeutic V.