Significance of Sufficient Neck Flexion During Magnetic Resonance Imaging in the Diagnosis of Hirayama Disease: Report of Two Cases

It is difficult to distinguish Hirayama disease (HD) from other mimicking disorders in adolescent patients with distal upper limb weakness. The prevailing theory of HD postulates that the lower cervical cord is susceptible to compression during neck flexion because of insufficient growth of the dura relative to the spinal column. Confirmation of a dynamic change in the dorsal epidural space on magnetic resonance imaging (MRI) during neck flexion is essential for diagnosing HD. However, neck flexion MRI has not been routinely performed in juvenile patients with distal upper limb weakness in the absence of suspected HD. We report two cases of HD that were initially confused with other diseases because of insufficient or absent cervical flexion during MRI. Full-flexion MRI showed typical findings of HD in both cases. Our cases suggest that dynamic cervical MRI in the fully flexed position is necessary for evaluating suspected HD.

Two Cases of Hirayama Disease in a Pediatric Clinic / 대한소아신경학회지

We report two pediatric cases with Hirayama disease—a 16-year-old boy with a left wrist drop and a 14-year-old-boy with weakness and muscle atrophy of right hand. Motor nerve conduction study revealed decreased motor nerve action potential amplitudes in the ulnar nerve and radial nerve of the affected hands. The former patient showed normal magnetic resonance imaging (MRI) of the cervical spine, but the latter showed mild, asymmetric thinning of the anterior spinal cord at levels C5 to C7. Following active rehabilitation and avoidance of neck flexion, no further progression of neurological findings was noticed. These clinical findings were typical of Hirayama disease. We show that timely and accurate diagnosis for Hirayama disease is possible with awareness of disease history, careful physical examination, and the use of neurophysiological studies and MRI studies.

Enfermedad de hirayama en un adolescente / Hirayama disease observed in an adolescent

La Enfermedad de Hirayama -o amiotrofia monomélica- es una afección de baja frecuencia y escasamente reportada en la edad pediátrica. Se presenta el caso clínico de un adolescente de 15 años de edad con disminución de la fuerza muscular y pérdida de la masa muscular, que comenzó a los 10 años de edad por la mano izquierda, y le afectó posteriormente el antebrazo. Mantuvo un curso progresivo durante 3 años, para luego mantenerse estable. El electromiograma de aguja arrojó lesión de axones motores o motoneuronas dependientes de los miotomas C7-T1, y en menor grado, C5-C6. En la tomografía axial computarizada con contraste endovenoso en marcada flexión cervical, se observó desde C7-T2 una evidente ectasia venosa posmedular asimétrica, predominantemente del lado izquierdo, por congestión del plexo venoso vertebral posterior interno. En este paciente la enfermedad se detuvo espontáneamente, en otros casos es necesario limitar la motilidad de la columna con el uso de un collar cervical, y solo llegar a la cirugía en los casos más severos de evolución rápida.

Hirayama disease or monomelic amyotrophy is a low frequent, barely reported illness at pediatric ages. Here is the clinical case of 15 years-old boy that presented with reduced muscular strength and loss of muscle mass; this condition began at the age of 10 year in his left hand and then affected the forearm. The illness progressed for three years and then remained stable. The needle electromyogram showed a lesion in C7-T1 myotome-depending motor axons or motoneurons and to less extent in those C5-C6 depending ones. The venous contrast computed tomography on a marked cervical cord flexion position; it was observed an evident asymmetric postmedullary vein ectasia from the C7-T2 myotomes, mainly on the left side, caused by the internal posterior vertebral vein plexus congestion. There was spontaneous remission of the disease in this patient, but it is necessary in other cases to limit the cervical cord motility with the use of a collar and to only perform surgery in the most rapidly evolving and severe cases.

Rare case of Hirayama’s disease.

Hirayama‟s disease is a rare benign neurological disorder also known as monomelic amyotrophy, Sobue disease, Juvenile Muscular Atrophy of Distal Upper Extremity (JMADUE). It mainly affects young males in their second or third decades and is most commonly seen in Asian countries like Japan, Malaysia and India. In majority of the cases the cause of the disease is unknown. An 18 year male came with weakness in his right hand and forearm since 1 year. Examination revealed weakness and wasting of muscles of forearm and hand without lower limb involvement and normal deep tendon reflexes. MRI showed focal short segment hyperintense signal in the ventral and right lateral aspect of the cervical cord at C5-C6 level with the involved segment measuring 4x3mm in size. Based on clinical and radiological features a diagnosis of focal amyotrophy was made. Patient is given a cervical collar to prevent flexion at the neck and physiotherapy in the form of hand and forearm exercises were started. Regular follow up of the patient once every 2 months is being done. Hirayama‟s disease is a rare, benign, self-limiting neurological disorder. Early diagnosis and management by preventing cervical flexion with the help of a cervical collar has shown to halt the progression of the disease.

Monomelic Amyotrophy after Permethrin Poisoning.

Monomelic amyotrophy (MMA) known as Hirayama disease (HD). The first report appeared in 1959 when Hirayama described 12 patients [1] then, a large group of patients was found from Japan [2,3]. MMA from South India was also reported in 1984 [4]. The disease accounted for males over 80% of cases, especially between 15 and 25 years of age. The disorder has been recognized as, unilateral or bilateral asymmetric atrophy of hand and forearm with sparing of brachioradialis giving the characteristic appearance of oblique amyotrophy. Symmetrically bilateral disease has also been recognized. It is believed to be a cervical flexion myelopathy [5]. Pyrethroids are used as insecticides due to their high potency. These are highly toxic to a wide range of insects but have low toxicity to humans. Pyrethroids are known to cause neurotoxicity in humans like seizures, tremors, and dizziness. Motor neuron damage has been reported in acute toxicity due to ingestion of pyrethroids and organochlorines [6] and MND (Motor neuron disease) like features after chronic exposure has been reported [7]. Here a case of monomelic amyotrophy following massive ingestion of permethrin, amytriptyline and benzodiazepine tablets is reported.

Monomelic Amyotrophy (Hirayama Disease) With Upper Motor Neuron Signs: A Case Report

Monomelic amyotrophy (MMA), also known as Hirayama disease, is a sporadic juvenile muscular atrophy in the distal upper extremities. This disorder rarely involves proximal upper extremities and presents minimal sensory symptoms with no upper motor neuron (UMN) signs. It is caused by anterior displacement of the posterior dural sac and compression of the cervical cord during neck flexion. An 18-year-old boy visited our clinic with a 5-year history of left upper extremity pain and slowly progressive weakness affecting the left shoulder. Atrophy was present in the left supraspinatus and infraspinatus. On neurological examination, positive UMN signs were evident in both upper and lower extremities. Electrodiagnostic study showed root lesion involving the fifth to seventh cervical segment of the cord with chronic and ongoing denervation in the fifth and sixth cervical segment innervated muscles. Cervical magnetic resonance imaging (MRI) showed asymmetric cord atrophy apparent in the left side and intramedullary high signal intensity along the fourth to sixth cervical vertebral levels. With neck flexion, cervical MRI revealed anterior displacement of posterior dural sac, which results in the cord compression of those segments. The mechanisms of myelopathy in our patient seem to be same as that of MMA. We report a MMA patient involving proximal limb with UMN signs in biomechanical concerns and discuss clinical importance of cervical MRI with neck flexion. The case highlights that clinical variation might cause misdiagnosis.

Response of Hirayama disease to surgical intervention: case report.

Hirayama disease also known as monomelic amyotrophy, primarily involves distal upper limb extremities. It differs from the known types of motor neuron diseases because of its nonprogressive behavior and pathologic findings of focal ischemic changes in the anterior horn of the lower cervical cord. We present a young male with Hirayama disease who had a left upper extremity involvement which was progressive in nature. He didn’t respond with initial treatment of cervical collar. Consequently surgical intervention improves muscle weakness and decrease the neurological deficit.

Association of the X-linked Androgen Receptor Leu57Gln Polymorphism with Monomelic Amyotrophy

Monomelic amyotrophy (MA), also known as Hirayama disease, occurs mainly in young men and manifests as weakness and wasting of the muscles of the distal upper limbs. Here, we sought to identify a genetic basis for MA. Given the predominance of MA in males, we focused on candidate neurological disease genes located on the X chromosome, selecting two X-linked candidate genes, androgen receptor (AR) and ubiquitin-like modifier activating enzyme 1 (UBA1). Screening for genetic variants using patients' genomic DNA revealed three known genetic variants in the coding region of the AR gene: one nonsynonymous single-nucleotide polymorphism (SNP; rs78686797) encoding Leu57Gln, and two variants of polymorphic trinucleotide repeat segments that encode polyglutamine (CAG repeat; rs5902610) and polyglycine (GGC repeat; rs3138869) tracts. Notably, the Leu57Gln polymorphism was found in two patients with MA from 24 MA patients, whereas no variants were found in 142 healthy male controls. However, the numbers of CAG and GGC repeats in the AR gene were within the normal range. These data suggest that the Leu57Gln polymorphism encoded by the X-linked AR gene may contribute to the development of MA.

Clinical Characteristics, Electrodiagnostic, and Imaging Findings of Atypical Forms of Motor Neuron Disease

OBJECTIVE: To describe the clinical characteristics, electrodiagnostic, and imaging findings of Hirayama disease (HD), late onset monomelic amyotrophy (LMA), and brachial amyotrophic diplegia (BAD). METHOD: A retrospective analysis of the medical records, electrodiagnostic, and imaging findings of 12 patients (4 HD, 2 LMA, 6 BAD) was done. For patients whose last clinic follow-up exceeded 6 months a telephone survey was done to see if there were any symptom changes. RESULTS: The clinical, electrodiagnostic, and imaging findings of the HD and BAD patients were similar to previous studies. Except for a later onset, age disease duration was too short to distinguish LMA from HD or other motor neuron diseases. One patient in the BAD group progressed to amyotrophic lateral sclerosis (ALS) and another died due to undetermined respiratory failure. These two patients showed abnormalities in their lower extremities, thoracic paraspinal, and craniocervical muscles on needle electromyography. Except for another patient, none of the other three patients showed abnormalities in their lower extremities, thoracic paraspinals, or craniocervical muscles on needle electromyography. CONCLUSION: HD and BAD can be considered as separate disease entities. However, a longer follow-up period than previously recommended is necessary to differentiate BAD from ALS. Follow-up period was too short to determine whether LMA can also be considered as a separate disease entity.

Upper limb proximal form of benign monomelic amyotrophy: on purpose of 2 cases / Amiotrofia monomélica benigna forma proximal de membro superior: a propósito de 2 casos

Benign monomelic amyotrophy (BMA) is a rare form of motor neuron disease of unknown cause and it?s characterized by weakness and muscular atrophy restricted to an upper or lower limb, usually in the distal part, absence of upper motor neuron signs and self limited course. In this report we describe the clinical and electromyographic features of two young men with BMA in the proximal portion of the right upper limb, a location of BMA rarely described in the literature.

Amiotrofia Monomélica Benigna (AMB) é uma entidade rara do neurônio motor, de causa desconhecida, caracterizada por fraqueza muscular e amiotrofia restritas a 1 membro superior ou inferior, frequentemente em terço distal, sem comprometimento da via piramidal e cursoautolimitado. Descrevemos os achados clínicos e eletroneuromiográficos de 2 pacientes jovens com AMB na porção proximal do membro superior, localização raramente descrita na literatura.

Clinical Features of Brachial Amyotrophic Diplegia

BACKGROUND: The purpose of this study was to describe a pure lower motor neuron disease in adults that is isolated to the upper limbs over time and to emphasize a differential diagnosis from other motor neuron diseases or motor neuropathies. METHODS: We reviewed retrospectively five male patients who had a bilateral upper limb weakness without any sensory changes confirmed by clinical and electrophysiological examinations at least 2 years after onset. RESULTS: Initially weakness remained largely confined to the arms. It then progressed slowly during the follow-up periods ranging from about 5 to 7 years since onset. However, weakness and muscle atrophy spared the lower limbs, respiratory and bulbar musculatures. The patients did not develop any bulbar dysfunctions or pyramidal tract signs. They were still able to ambulate at the end of follow-up. CONCLUSIONS: Brachial amyotrophic diplegia presenting with severe weakness that is completely confined to the upper limbs over time, without upper motor neuron signs, might be a stable and relatively benign variant of motor neuron disease. It should be differentiated from other motor neuropathies.