MRI findings in Hirayama's disease: flexion-induced cervical myelopathy or intrinsic motor neuron disease?

Anterior cervical discectomy and fusion for the treatment of pediatric Hirayama disease

PURPOSE

Hirayama disease, a rare cervical myelopathy in children and young adults, leads to progressive upper limb weakness and muscle loss. Non-invasive external cervical orthosis has been shown to prevent further neurologic decline; however, this treatment modality has not been successful at restoring neurologic and motor function, especially in long standing cases with significant weakness. The pathophysiology remains not entirely understood, complicating standardized operative guidelines; however, some studies report favorable outcomes with internal fixation. We report a successful surgically treated case of pediatric Hirayama disease, supplemented by a systematic review and collation of reported cases in the literature.

METHODS

A review of the literature was performed by searching PubMed, Embase, and Web of Science. Full-length articles were included if they reported clinical data regarding the treatment of at least one patient with Hirayama disease and the neurologic outcome of that treatment. Articles were excluded if they did not provide information on treatment outcomes, were abstract-only publications, or were published in languages other than English.

RESULTS

Of the fifteen articles reviewed, 63 patients were described, with 59 undergoing surgery. This encompassed both anterior and posterior spinal procedures and 1 hand tendon transfer. Fifty-five patients, including one from our institution, showed improvement post-treatment. Eleven of these patients were under 18 years old.

CONCLUSION

Hirayama disease is an infrequent yet impactful cervical myelopathy with limited high-quality evidence available for optimal treatment. The current literature supports surgical decompression and stabilization as promising interventions. However, comprehensive research is crucial for evolving diagnosis and treatment paradigms.

Characteristics of Hirayama Disease in Young South Korean Soldiers

BACKGROUND AND PURPOSE

The purpose of this study was to describe the clinical presentation and features in electrodiagnostic and imaging investigations of young South Korean males diagnosed with Hirayama disease (HD).

METHODS

We reviewed the electronic medical records of South Korean enlisted soldiers who were diagnosed with HD and discharged from military service during 2011-2021. We investigated the clinical characteristics and results of electrodiagnostic and magnetic resonance imaging (MRI) investigations. We analyzed laterality and identified the involved muscles using needle electromyography (EMG). Loss of lordosis, localized cervical cord atrophy, loss of attachment between the posterior dura and subjacent lamina, asymmetric flattening of the cord, crescent-shaped mass in the posterior epidural space, and noncompressive intramedullary T2-weighted high signal intensity were investigated using neutral- or flexion-position MRI.

RESULTS

Forty-two male patients aged 20.2±0.8 years (mean±standard deviation) were identified. All patients complained of hand weakness, and 10 complained of hand tremor (23.8%). Four patients (9.5%) had symptoms in both upper limbs, and five (11.9%) had sensory disturbances. Needle EMG revealed that muscles in the C7-T1 myotome were commonly involved, and C5-C6 involvement of the deltoid (10.5%) and biceps brachii (12.5%) was also observed. In cervical MRI, localized cord atrophy (90.0%) was the most characteristic finding, and cord atrophy was most severe at the C5-C6 level (58.3%).

CONCLUSIONS

This is the first description of a large number of patients with HD in South Korea. The clinical presentation and features found in electrodiagnostic and imaging investigations will improve the understanding of HD in the young South Korean male population.

Hirayama's disease associated with cervical deformity and spinal cord compression: a case report from Sweden

BACKGROUND

Hirayama's disease (HD) is most common in young males, and previous studies are predominantly from Asian countries. The cause of HD is unknown but the most common theory about the pathology speculates on forward bending that causes a compression of the dura mater and the anterior horn of the spinal cord against the vertebra during an overstretch flexion that may result in myelopathy. Both anterior and posterior cervical surgical approaches have been shown to be effective in stopping the disease and improving function; however, HD is also reported to be a self-limited disease, and treatment with a cervical collar may be an alternative for these patients.

CASE REPORT

We report HD in a 17-year-old male from Sweden who underwent surgical treatment with a 2 level anterior cervical discectomy and fusion (ACDF) due to neurological progression from HD after conservative treatment.

CONCLUSION

HD is rare and is easily overlooked. Surgical intervention shows promising results for neurological progression, but HD is also reported to be a self-limited disease.

Association of joint hypermobility with range of cervical motion and its impact on the motor unit loss in patients with Hirayama disease

INTRODUCTION/AIMS

Some patients with Hirayama disease (HD) may have generalized joint hypermobility (GJH), which may excessively increase cervical range of motion (ROM) and then worsen the HD. The purpose of this study was to identify the frequency of GJH in HD patients and to analyze the effect of GJH on cervical ROM and the severity of HD.

METHODS

The Beighton scoring system (≥4) was used to diagnose GJH in 84 HD patients. All patients underwent assessments of cervical-flexion/extension ROM; motor unit number estimation in bilateral abductor pollicis brevis (APB) muscles; handgrip strength; and the disabilities of the arm, shoulder, and hand assessments.

RESULTS

Concomitant GJH was identified in 20 (23.8%) HD patients. The HD patients with GJH exhibited greater cervical-flexion (P < .001) and cervical-extension (P = .033) ROM than those without GJH. Both greater single motor unit potential amplitudes (symptomatic side: P = .005; less-symptomatic side: P = .011) and lower motor unit numbers (symptomatic side: P = .008; less-symptomatic side: P = .013) in bilateral APB, along with lower compound muscle action potential amplitudes on the symptomatic-side APB (P = .039), were observed in patients with GJH than those without GJH. There was a mild negative correlation between motor unit number and cervical-flexion ROM in HD patients (symptomatic side: r = -0.239, P = .028; less-symptomatic side: r = -0.242, P = .027).

DISCUSSION

The frequency of GJH in HD patients may be higher than in the general population. Importantly, GJH may exacerbate excessive cervical-flexion ROM, thereby worsening motor unit loss in HD patients. A cautious approach should be taken when treating HD due to possible comorbid GJH.

[Monomelic amyotrophy]

Monomelic amyotrophy, also known as Hirayama disease, is a rare neurological disorder characterized by focal and latent onset of upper limb weakness and atrophy in the absence of sensory deficits, bulbar or pyramidal signs. It usually occurs in young patients. The disease usually begins unnoticeably and progresses slowly, and can manifest itself as unilateral or asymmetrical weakness, as well as atrophy of the distal upper limb. Sensory disturbances, reflex changes and signs of lesions of lower motor neurons are rare. This article describes a case of a patient with complaints of weakness not only in the upper but also in the lower extremities.

Cervical Transdural Discectomy with Laminoplasty for the Treatment of Multi-segment Cervical Spinal Stenosis Accompanied with Cervical Disc Herniation: Technical Note and Clinical Outcome

Objective

To describe the surgical technique of cervical transdural discectomy with laminoplasty (CTDL) for the treatment of multi‐segment cervical spinal stenosis (CSS) accompanied with cervical disc herniation (CDH) and investigate its surgical outcomes and complications.

Methods

This was a clinical study. Between 2012 and 2018, 31 patients (13 males and 18 females) with multi‐segment CSS (over two cervical segments) accompanied with huge CDH and underwent CTDL were enrolled in this study. The details of CTDL technique with general anesthesia was described by the authors. The average follow‐up period of patients was 65.03 months (range from 24 to 126 months). Perioperative parameters such as age, sex, operative level, operative time, estimated blood loss, ambulation time, and operative complications were recorded. The results of clinical metrics such as the visual analog scale (VAS) and Japanese Orthopaedic Association (JOA) scores in the preoperative and during the follow‐up period were obtained and used to evaluate clinical outcomes. Radiographic improvement was evaluated by the compression ratio, sagittal maximum spinal cord compression (SMSCC), and cervical range of motion (ROM). The preoperative and postoperative follow‐up parameters (VAS, JOA, Compression ratio, SMSCC, and ROM) were assessed with paired t test. A P‐value <0.05 was considered statistically significant.

Results

In the study, the mean age of the 31 patients was 55.23 ± 10.97 years. The mean operative time was 192.45 ± 24.17 min (ranging from 150 to 245 min), and intraoperative blood loss was 322.58 ± 129.00 mL (ranging from 150 to 600 mL). The VAS neck pain was improved significantly over the follow‐up period (P < 0.05, respectively). The VAS arm pain improved significantly from 6.26 ± 0.93 preoperatively to 1.74 ± 0.63 at 24 months postoperatively (P < 0.001). There was no significant difference in improvement of VAS arm pain between 24 months postoperatively and final follow‐up (P = 0.180). Compared with preoperative JOA score, JOA score was significantly improved at 24 months postoperatively (14.79 ± 1.84 vs 9.66 ± 2.81, P < 0.001). Meanwhile, there were no statistically significant differences between the final follow‐up and the postoperative JOA scores (15.08 ± 1.71 vs 14.79 ± 1.84, P = 0.051). Postoperative patients showed significantly higher index of compression ratio (58.30 ± 8.51 vs 27.17 ± 3.89, P < 0.001) and lower SMSCC (25.12 ± 5.67 vs 33.66 ± 5.38, P < 0.001). In addition, there was no significant difference between preoperative and postoperative cervical ROM (P = 0.740). One patient observed postoperative symptom of C₆ nerve root injury, which was resolved within 24 months after the surgery; meanwhile, the neurological monitoring also reflected the intraoperative stretching of the C₆ nerve root. Two cases involved postoperative cerebrospinal fluid (CSF) leakage which may have been related to laceration of dura mater.

Conclusions

This study suggested that CTDL technique could acquire satisfactory surgical outcomes for patients with multi‐segment CSS accompanied with CDH, but the surgical indications of the patients need to be selected strictly.

An Atypical Presentation of Hirayama Disease With Lower Limb Myelopathic Symptoms Only

ABSTRACT

Hirayama disease is a rare neuromuscular disease, which classically presents as lower motor neuron weakness and atrophy in the upper limbs and specifically the C7-T1 myotomes. Proposed pathogenesis relates to microcirculatory dysfunction in the territory of the anterior spinal artery caused by epidural venous plexus engorgement with forward displacement of the posterior dura and spinal cord during neck flexion, leading to chronic ischemic changes in the lower cervical anterior horn cells. Diagnosis hinges upon clinical and radiographic findings, and treatment is generally conservative given the self-limited nature of the disease. Here, we present a case with classic radiologic findings of Hirayama disease with lower limb myelopathic findings alone. This case raises the question of whether the pathophysiology leading to focal anterior cervical myelopathy in forward flexion could present along a broader clinical spectrum than previously recognized, from complete asymptomaticity, to classic Hirayama disease with C7-T1 atrophy, to cervical myelopathy with long tract signs.

The Influence of "Loss of Attachment" on the Outcome of Anterior Cervical Fusion Procedures in Patients With Hirayama Disease

The objective of this study was to identify the influence of the measurements of "loss of attachment" on the surgical outcome in Hirayama disease (HD). Forty-two patients with HD underwent neutral and cervical-flexion magnetic resonance imaging (MRI) before surgery, and the cervical-flexion MRI was repeated at the 3-month postoperative visit. The longitudinal separation range (LSR) of loss of attachment, the maximum forward-shifting (MFS) degree in the cervical cord, and the relative morphological changes of the cervical cord were measured on MRI. Additionally, all patients underwent handgrip strength (HGS) testing, the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and Medical Research Council scales at the 1-year postoperative visit. Postoperatively, the cervical-flexion X/Y and the LSR decreased significantly at a mean of 94.17±8.65 days (range, 75-110 days) (P<.01), while the cervical-flexion A/B increased (P<.01). Loss of attachment was resolved in fused segments in all 42 patients, but there were 7 instances of residual loss of attachment at adjacent segments. Twenty (47.6%) of the 42 patients' DASH scores decreased at the 1-year postoperative visit. According to the logistic regression analysis, both LSR and MFS were related to the surgical outcomes. Receiver operating characteristic curve analysis found that area under the curve and cutoff values were 0.959 and 4.5, respectively (P<.05) for LSR and 0.782 and 0.215, respectively (P<.05) for MFS. Anterior cervical fusion procedures can effectively improve the abnormal loss of attachment and prevent further progression of HD. The LSR is an important risk factor for the prognosis, and longer fused segments may be required when the LSR is 5 segments or more. [Orthopedics. 2021;44(1):30-37.].

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.

CAN anterior cervical fusion procedures prevent the progression of the natural course of Hirayama disease? An ambispective cohort analysis

OBJECTIVE

To clarify the effectiveness of anterior cervical fusion (ACF) in the treatment of Hirayama disease (HD).

METHODS

Sixty-nine HD patients who accepted ACF procedures underwent dynamic F-waves before and soon after operation, and 36 of the 69 patients underwent pre- and postoperative magnetic resonance imaging (MRI). Motor unit number estimation, handgrip strength (HGS) and disabilities of arm, shoulder and hand (DASH) were performed in these 36 HD patients and in the other 24 patients who accepted neither neck-collar support nor operation, and these tests were reassessed about one year after initial test.

RESULTS

Postoperatively, dynamic F-wave abnormalities were observed in fewer HD cases (2/69 vs. 25/69), and neck-flexion MRI abnormalities decreased significantly (P < 0.05). Compared with motor unit loss in patients who were untreated, follow-up analysis demonstrated no differences in motor unit, HGS or DASH in HD patients who underwent operation (P > 0.05), and mild recovery of motor units was observed in patients with preoperative abnormal dynamic F-waves (P < 0.05).

CONCLUSIONS

ACF procedures can immediately remove neck-flexion abnormalities and prevent or delay the progression of HD.

SIGNIFICANCE

ACF procedures may provide effective, reliable and alternative methods for the treatment of HD, especially in HD patients with functional evidence of neck-flexion abnormalities.

Benign monomelic amyotrophy with lower limb involvement in an adult: A case report

RATIONALE

Monomelic amyotrophy (MMA) is a benign motor neuron disease with bilateral muscular atrophy in asymmetry and abnormal in the electromyography (EMG). However, we report a case by the muscle biopsy which shows symptoms of slowly progressive amyotrophy despite having a normal EMG.

PATIENT CONCERNS

A 51-year-old male was diagnosed with a lower limb amyotrophy, insidious at the onset and located in the distal thigh and the proximal crus near the knee, slowly progressive weakness, and wasting of his right gastrocnemius muscle for the last 20 years.

DIAGNOSES

He was diagnosed with MMA by the clinical profile, natural history, examinations, and the biopsy.

INTERVENTIONS

We perform dynamic physical therapy for the patient in this case.

OUTCOMES

The positive effects of dynamic physical therapy in this case with MMA were shown in this report.

LESSONS

The outcome of physical therapy is satisfactory.

Segmental Spinal Muscular Atrophy Localised to the Lower Limbs: First case from Oman

Spinal muscular atrophy (SMA) is a genetic lower motor neuron disease. It usually involves all of the skeletal muscles innervated by the anterior horn cells of the spinal cord. In rare cases, there is also localised involvement of the spinal cord. We report a 10-year-old boy who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in 2015 with muscle weakness restricted to the lower limbs. The presence of a homozygous deletion within the survival of motor neuron 1 gene confirmed the diagnosis of SMA. To the best of the authors' knowledge, this is the first report of an Omani patient with segmental SMA involving only the lower limbs. Treatment for this rare and relatively benign form of SMA is symptomatic and includes physiotherapy.

Hirayama disease (monomelic amyotrophy) clinically confused for carpal tunnel syndrome

Hirayama disease (HD) is a rare motor neuron disorder that involves a single upper extremity. It is clinically characterized by weakness and atrophy of the muscles of the hand and forearm. This article presents a 19-year-old woman who visited the orthopedics outpatient clinic with weakness and atrophy in her right hand and was clinically diagnosed with advanced stage carpal tunnel syndrome and scheduled for surgical intervention; she was later diagnosed with HD by an electrophysiological study. As a result, it has been found that a careful electrophysiological study and neurological examination can be used to diagnose HD. In this way, advanced stage carpal tunnel syndrome will be ruled out and patients will be spared from an unnecessary surgical operation.

Clinical Experiences of Uncommon Motor Neuron Disease: Hirayama Disease

Hirayama disease, juvenile muscular atrophy of the distal upper limb, is a rare disease predominantly affecting the anterior horn cells of the cervical spinal cord in young men. This cervical myelopathy is associated with neck flexion. It should be suspected in young male patients with a chronic history of weakness and atrophy involving the upper extremities followed by clinical stability in few years. Herein, we report 2 cases of Hirayama disease on emphasis of diagnostic approach and describe the pathognomonic findings at flexion magnetic resonance imaging.

Hirayama Disease with Proximal Involvement

Hirayama disease is a slowly progressing benign motor neuron disease that affects the distal upper limb. A 29-year-old man visited the hospital with a 1-year history of weakened left proximal upper limb. He was diagnosed with Hirayama disease 9 years ago, while there was no further progression of the muscle weakness afterward. Atrophy and weakness was detected in proximal upper limb muscles. Magnetic resonance imaging and somatosensory evoked potentials were normal. Needle electromyography showed abnormal findings in proximal upper limb muscles. Our patient had Hirayama disease involving the proximal portion through secondary progression. Clinical manifestation and accurate electromyography may be useful for diagnosis. Rare cases with progression patterns as described here are helpful and have clinical meaning for clinicians.

Hirayama's disease: an Italian single center experience and review of the literature

BACKGROUND

Hirayama's disease (HD), is a benign, self-limited, motor neuron disease, characterized by asymmetric weakness and atrophy of one or both distal upper extremities. In the present study we report the clinical, electrophysiological and MRI features of a group of Italian patients, with review of the literature. Moreover we propose an optimized MRI protocol for patients with suspected or diagnosed HD in order to make an early diagnosis and a standardized follow up.

METHODS

Eight patients with clinical suspicion of Hirayama disease underwent evaluation between January 2007 and November 2013. All patients underwent standard nerve conduction studies (NCS), electromyography (EMG) and motor/sensory evoked potentials (MEP/SEP). Cervical spine MRI studies were conducted with a 1.5 Tesla MRI scanner in neutral and flexion position, including sagittal T1-weighted sequences and sagittal and axial T2-weighted sequences. The following diagnostic features were evaluated: abnormal cervical curvature, localized cervical cord atrophy in the lower tract (C4-C7), presence of cord flattening (CF), intramedullary signal hyperintensity on T2 weighted sequences, anterior shifting of the posterior wall of the cervical dural sac (ASD) and presence of flow voids (EFV) in the posterior epidural space during flexion.

RESULTS

All patients complained of weakness in hand muscles as initial symptoms, associated with hand tremor in three of them and abnormal sweating of the hand palm in two of them. No sensory deficits and weakness at lower limbs were reported by any patients. Distal deep tendon reflexes at upper limbs were absent in all patients with the absence of the right tricipital reflex in one of them. Deep tendon reflexes at lower limbs were normal and no signs of pyramidal tract involvement were present. The clinical involvement at onset was unilateral in six patients (three left-sided and three right-sided) and bilateral asymmetric in two of them, with the right side more affected. With the progression of the disease all patients but one experienced weakness and wasting of hand muscles and forearm bilaterally, but still asymmetric. The duration of the progression phase of the disease ranged from eight months to three years. In all patients, NCS and EMG findings were consistent with a spinal metameric disorder involving the C7-T1 myotomes bilaterally; sensory conduction and electrophysiologic features at lower limbs were normal. MEP and SEP were normal and we did not observe the disappearance of the spinal potential during the neck flexion in any of the patients. MRI is the best diagnostic tool in the diagnosis of HD; it can confirm clinical diagnosis and exclude other conditions responsible for the neurological deficits leading to a correct patient management and therapy, limiting arm impairment. On MRI all patients had loss of the normal cervical lordosis (100%). Five patients had loss of attachment of posterior dural sac and anterior dural shift on flexion MRI with presence of flow voids from venous plexus congestion (62.5%); three patients had no anterior dislocation of the dural sac and no epidural vein congestion. Two patients showed localized cord atrophy, one at C5-C6 and the other at C6-C7 level (25%). Three patients had T2 intramedullary hyperintensities (37.5%) and cord flattening (CF) was present in 5 patients of 8 (62.5%).

CONCLUSIONS

HD is a rare entity and a self-limited condition, but it has to be early differentiated from other diseases that may determine myelopathy and amyotrophy to establish a correct therapy and limit arm impairment. MRI is very important to confirm the clinical suspect of HD and a standardized MRI protocol using axial and sagittal images in both neutral and flexing position is needed, in order to diagnose and follow up affected patients.

Correlations of clinical, neuroimaging, and electrophysiological features in Hirayama disease

Hirayama disease (HD) is characterized by development of asymmetric forearm muscle atrophy during adolescence with or without focal cervical spinal cord atrophy. The purpose of this study is to assess the correlation of clinical symptoms, disease progression, and electrophysiological findings with cervical spine magnetic resonance imaging (MRI) findings.The medical records, cervical spine MRIs, and electrophysiological findings of 44 HD patients were retrospectively reviewed and analyzed.Denervation changes in any single C5 to C7 root-innervated muscle (deltoid, biceps, triceps, or extensor digitorum communis) occurred more frequently in the 25 patients with cord atrophy than the 19 patients without cord atrophy (88% vs 53%, P = 0.02). Onset age, duration of disease progression, neurological examinations, nerve conduction study, and electromyographic findings from individual muscles were similar between patient groups.Compared with HD patients without cord atrophy, HD patients with cord atrophy experience a more severe denervation change in C5 to C7 root-innervated muscles.

Monomelic amyotrophy: clinical profile and natural history of 279 cases seen over 35 years (1976-2010)

Our objective was to study the clinical characteristics and natural history of monomelic amyotrophy (MMA). We used a retrospective study of 279 patients diagnosed to have either upper (Hirayama disease) or lower limb MMA. Results showed that brachial MMA (BMMA) occurred in 224 patients (male:female, 9:1). Mean age of onset was 19.5 ± 4.18 years. Progression occurred over less than five years in the majority (95.9%) of patients. Duration at the last follow-up was: up to five years in 61.4%, 5-10 in 21.3%, 10-15 in 7.2%, > 15 years in 10.1%. MRI showed asymmetrical lower cervical cord atrophy in 44.6% of patients. Crural MMA (CMMA) occurred in 55 patients (male:female, 13:1). Mean age of onset was 21.38 ± 5.3 years. Similar to BMMA, most cases (65.5%) had onset between 15 and 25 years of age. Total duration of illness at the last follow-up was up to five years in 52.7%, 10 and beyond in 47.3%. In conclusion, a large cohort of patients with monomelic amyotrophy seen over 35 years (1976-2010) is described. Study data support the clinical findings and its natural history with long term follow-up, and the findings emphasize that monomelic amyotrophy is a 'benign' condition with a self-limiting course.

Hirayama disease in children from mainland of China

Hirayama disease is characterized by asymmetrical focal weakness and atrophy of the distal upper limbs with onset in the teens and early 20s. This retrospective study aims to review clinical features of the children (onset before the age of 18 years) with Hirayama disease from mainland of China. Sixty-five children who fulfilled the clinical criteria for Hirayama disease were enrolled. The mean age of onset was 15.7 years, 3.3 years later than the peak age for the normal growth curve. Electrophysiology studies showed chronic denervation changes in C7-T1 segments with normal sensory nerve conduction. Flexion cervical magnetic resonance imaging (MRI) showed forward shifting of the posterior dural sac and engorgement of the posterior epidural venous plexus. Therapeutic intervention with cervical collar can induce a premature arrest of disease progression. Knowledge and awareness of Hirayama disease will facilitate diagnosis and therapeutic intervention in its early stages.

Nosology of juvenile muscular atrophy of distal upper extremity: from monomelic amyotrophy to Hirayama disease--Indian perspective

Since its original description by Keizo Hirayama in 1959, "juvenile muscular atrophy of the unilateral upper extremity" has been described under many nomenclatures from the east. Hirayama disease (HD), also interchangeably referred to as monomelic amyotrophy, has been more frequently recognised in the west only in the last two decades. HD presents in adolescence and young adulthood with insidious onset 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. Believed to be a cervical flexion myelopathy, HD differs from motor neuron diseases because of its nonprogressive course and pathologic findings of chronic microcirculatory changes in the lower cervical cord. Electromyography shows features of acute and/or chronic denervation in C7, C8, and T1 myotomes in clinically affected limb and sometimes also in clinically unaffected contralateral limb. Dynamic forward displacement of dura in flexion causes asymmetric flattening of lower cervical cord. While dynamic contrast magnetic resonance imaging is diagnostic, routine study has high predictive value. There is a need to lump all the nomenclatures under the rubric of HD as prognosis in this condition is benign and prompt diagnosis is important to institute early collar therapy.

Hirayama disease is a pure spinal motor neuron disorder--a combined DTI and transcranial magnetic stimulation study

Hirayama disease (HirD) is a juvenile spinal muscular atrophy predominantly affecting young men with an initially progressive course followed by a stable plateau within several years. It is a matter of debate whether HirD is a widespread motor neuron or more focal cervical cord disease. Whether the supraspinal pathways of the corticospinal tract (CST) are also affected has not been studied systematically. We analyzed CST integrity in seven HirD patients and 11 controls of similar age and gender using diffusion tensor imaging at a 1.5-T scanner and central motor conduction time (CMCT) using transcranial magnetic stimulation. The apparent diffusion coefficient, fractional anisotropy, and axial and radial diffusivity coefficients were determined bilaterally at four representative CST levels and along the whole CST using a probabilistic fiber tracking approach. There were no differences between the initially affected and the contralateral side in HirD patients and no difference between HirD patients and controls for both the ROI-based and the whole CST analyses. Radial diffusivity of the CST was positively correlated with years of disease progression in HirD patients. CMCT was normal in HirD patients. Combined anatomical and functional measurements established normal integrity of the supraspinal CST in HirD patients lending support to the notion that HirD is a pure spinal motor neuron disorder.

Cervical spine MR imaging findings of patients with Hirayama disease in North America: a multisite study

BACKGROUND AND PURPOSE

Most studies of HD have been conducted in Asia, particularly Japan. To characterize the MR imaging findings of North American patients with HD, we reviewed neutral and flexion cervical MR imaging examinations performed for possible HD at 3 academic medical centers located in the Southeastern, Southwestern, and Midwestern regions of the United States.

MATERIALS AND METHODS

Three neuroradiologists assessed the MR imaging examinations in a blinded fashion and reached a consensus rating for LOA of the posterior dura to the spine, lower spinal cord atrophy, spinal cord T2 hyperintensity, loss of cervical lordosis, anterior dural shift with flexion, and confidence of imaging diagnosis. Final reference diagnosis was established separately with a retrospective chart review by a neurologist.

RESULTS

Twenty-one patients met the criteria for HD, all were North American males and all who reported their race were white. Seventeen patients did not meet the criteria and served as controls. Four imaging attributes, LOA, dural shift with flexion, consensus diagnosis of neutral images, and consensus diagnosis of combined neutral and flexion images were all able to discriminate the group with HD from the group without HD (P < .05 for each). Findings of HD were often present on neutral images, but the addition of flexion images increased diagnostic confidence.

CONCLUSIONS

MR imaging findings in white North American patients with HD include LOA on neutral images and forward displacement of the dura with flexion. Findings are often present on neutral MR images and, in the appropriate clinical scenario, should prompt flexion MR imaging to evaluate anterior dural shift.

A case of monomelic amyotrophy of the upper limb: MRI findings and the implication on its pathogenesis

Monomelic amyotrophy of the upper limb or Hirayama disease is mostly considered as an anterior horn disorder resulting from local ischemia, triggered by arterial compression from an anterior shifting of the posterior cervical dura upon neck flexion. However, such a dural shifting is not universally seen. We report on a Caucasian male patient who developed a slowly progressive unilateral distal hand weakness in his teens. His clinical and electromyographic findings were consistent with Hirayama disease. Local anterior cervical cord atrophy was observed without dural shifting on the dynamic magnetic resonance imaging. Axial magnetic resonance imaging demonstrated signal changes of "snake-eye" appearance in the cervical anterior horn region, similar to ischemic myelopathies caused by various etiologies. This case illustrated that even without dural shifting, a mechanism of anterior spinal cord ischemia could still be responsible for the pathogenesis of Hirayama disease.

Clinical and radiological profile of Hirayama disease: A flexion myelopathy due to tight cervical dural canal amenable to collar therapy

BACKGROUND

Hirayama disease (HD) is benign focal amyotrophy of the distal upper limbs, often misdiagnosed as motor neuron disease. Routine magnetic resonance imaging (MRI) is often reported normal.

OBJECTIVE

To study the clinicoradiological profile of hand wasting in young males.

MATERIALS AND METHODS

Patients presenting with insidious-onset hand wasting from March 2008 to May 2011 were evaluated electrophysiologically. Cervical MRI in neutral position was done in 11 patients and flexion contrast imaging was done in 10 patients.

RESULTS

All patients were males less than 25 years of age, with median age 23 years, except one patient who was 50 years old. Duration of illness was 3 months to 3 years. All (100%) had oblique amyotrophy, four (36%) cold paresis, 10 (91%) minipolymyoclonus and three (27%) had fasciculations. Regional reflexes were variably absent. Two patients (18%) had brisk reflexes of lower limbs with flexor plantars. Electromyography (EMG) showed chronic denervation in the C7-T1 myotomes. Neutral position MRI showed loss of cervical lordosis in 10/11 (91%), localized lower cervical cord atrophy in 9/11 (82%), asymmetric cord flattening in 11/11 (100%) and intramedullary hyperintensity in 2/11 (18%); flexion study showed loss of dural attachment, anterior displacement of dorsal dura, epidural flow voids in 9/10 (90%) and enhancing epidural crescent in 10/10 (100%). Clinical profile, imaging and electrophysiological findings of the patient aged 50 years will be described in detail as presentation at this age is exceptional. Collar therapy slowed progression in most cases.

CONCLUSION

Clinical features of HD corroborated well with electrophysiological diagnosis of anterior horn cell disease of lower cervical cord. While dynamic contrast MRI is characteristic, routine studies have a high predictive value for diagnosis. Prompt diagnosis is important to institute early collar therapy.

Hirayama disease in children from North America

Hirayama disease has been mainly reported from Asia; only a few cases are from the Western hemisphere, particularly North America. This is a retrospective chart review of patients < 18 years, diagnosed with Hirayama disease from a single center over 10 years. We diagnosed 6 children (4 boys), 15.1 ± 1.2 years of age. Symptom onset was 3 months to 3 years before presentation. All had unilateral or bilateral asymmetric distal upper extremity weakness without objective sensory loss. Oblique amyotrophy and cold paresis were noted in 5. On electromyography, acute-on-chronic denervation was most frequently noted in cervical-8 (C8) and thoracic-1 (T1) myotomes followed by cervical-7 (C7) myotome in both upper limbs, sparing C5-C6 myotomes. Cervical magnetic resonance imaging (MRI) was abnormal in 3. Symptoms progressed over a mean of 16.5 months. Treatment consisted of placement of cervical collar. Heightened awareness of this entity among pediatric neurologists in North America will lead to early diagnosis and intervention, avoiding unnecessary investigations.

[Motor neuron diseases]

Motor neuron diseases (MND) are a group of neurodegenerative disorders which are present in clinical, prognostic and genetic diversity. The most common MND are amyotrophic lateral sclerosis (ALS), proximal spinal muscular atrophy (SMA) and various forms of hereditary and sporadic lower motor neuron syndromes including hereditary motor neuropathies (HMN). Familial and "sporadic" forms of ALS and lower motor neuron syndromes are known. The essential pathogenic findings in MND have emerged from molecular biological examinations of the hereditary forms of MND. In ALS, one consistent neuropathological feature is intraneuronal protein inclusions which arise from TDP-43, FUS, SOD1 or ataxin-2 aggregations. TDP-43, FUS, SOD1 and ataxin-2 are multifunctional DNA/RNA-binding proteins which are involved in transcription regulation. SMA and HMN are associated with different genes whose gene products may also be involved in RNA processing. A disturbance in the regulation of RNA possibly represents an overlapping pathophysiological characteristic in MND. The elucidation of common pathways in the cascade of motor neuron degeneration is an essential point of departure for molecular genetically defined treatment strategies both in ALS and in hereditary and sporadic lower motor neuron syndromes.

Features of Hirayama Disease on Fully Flexed Position Cervical MRI

This study reports on cervical magnetic resonance imaging (MRI) performed in the fully flexed position in 13 male patients with Hirayama disease and 12 normal controls (males). The anterior–posterior diameter of the cervical cord at the superior margin of the C6 vertebral body was measured, as well as the angle between adjacent cervical bodies. Localized lower cervical-cord atrophy, cord flattening and abnormal signals in the posterior epidural space were studied. Patients demonstrated an increased angle between C5 and C6, and C6 cord lesions. There were significant differences between patients and controls in localized lower cervical-cord atrophy and cord flattening. Many patients were found to have a crescent-shaped high-intensity mass on T2WI MRI and a low-intensity mass on T1WI MRI in the posterior epidural space. In patients, there were specific imaging features of Hirayama disease on fully flexed MRI. Cervical MRI in the fully flexed position has significant value in the clinical diagnosis of Hirayama disease.

Mutational analysis of glycyl-tRNA synthetase (GARS) gene in Hirayama disease

Sporadic juvenile muscular atrophy of the distal upper extremity or Hirayama's disease (HD) and autosomal dominant motor distal neuronopathy/axonopathy (CMT2D/dSMA-V), produced by glycyl-tRNA synthetase (GARS) gene mutations, share some clinical features including: young age of onset, predilection for the distal upper extremity, asymmetry, sparing of proximal muscles and unusual cold sensitivity. However, incomplete penetrance of GARS gene mutations may account for apparently non-familial cases. In order to inquire whether GARS gene mutations are associated with HD we studied seven patients fulfilling the clinical and electrodiagnostic criteria for HD. All patients underwent MRI of cervical spine that excluded compressive myelopathy in neutral position and intramedullary pathology. Each patient was tested for the presence of mutations in GARS by sequencing all coding exons amplified from genomic DNA. No pathogenic mutations were found, excluding the role of GARS gene as a possible factor in the aetiology of HD in this cohort.

Spinal angiography and epidural venography in juvenile muscular atrophy of the distal arm "Hirayama disease"

We studied two 16-year-old males with juvenile muscular atrophy of the distal arm, "Hirayama disease," resulting in asymmetric atrophy and weakness of the distal upper extremities. Pathogenic theories include a compressive myelopathy with or without ischemia, and occasional cases are accounted for by genetic mutations. To specifically address the ischemia hypothesis we performed spinal angiography and epidural venography. Neck flexion during spinal angiography showed a forward shift of a nonoccluded anterior spinal artery without impedance to blood flow. Epidural venography demonstrated engorgement of the posterior epidural venous plexus without obstruction to venous flow. The findings do not support large vessel obstruction as a contributory factor. The Hirayama hypothesis continues to best explain the disease pathogenesis: neck flexion causes tightening of the dura and intramedullary microcirculatory compromise with resultant nerve cell damage. The age-related factor can most likely be accounted for by a growth imbalance between the vertebral column and the cord/dural elements. Resolution of progression is associated with cessation of body growth, after which the symptoms plateau or modestly improve. Muscle Nerve 40: 206-212, 2009.

Lack of epidural pressure change with neck flexion in a patient with Hirayama disease: case report

OBJECTIVE

Hirayama disease is a nonprogressive cervical myelopathy associated with epidural venous engorgement and spinal canal narrowing. It has been unclear whether dural venous pressure influences spinal cord injury in this illness.

CLINICAL PRESENTATION

An 18-year-old man presented with profound hand weakness and atrophy that had developed over a period of 1 year. Electromyographic, magnetic resonance imaging, and angiographic findings are presented.

INTERVENTION

The epidural space was accessed using a microcatheter technique. Pressure measurements were recorded with and without Valsalva maneuver in the inferior vena cava, vertebral veins, and epidural space at C4 and C6 in both the flexion and neutral positions. Cervical epidural venous pressure measurements in flexion and neutral positions are presented. The patient underwent duraplasty with C4 to T1 laminectomies and fusion using lateral mass screws and facet arthrodeses.

CONCLUSION

Lack of significant pressure change with neck flexion suggested that dural venous engorgement is passive and not the direct cause for spinal cord injury. Data presented herein and review of the literature suggest that surgical treatment targeting the underlying pathophysiological mechanism in Hirayama disease can benefit patients, especially early in the course of the disease.

Nationwide survey of juvenile muscular atrophy of distal upper extremity (Hirayama disease) in Japan

Juvenile muscular atrophy of the distal upper extremity (JMADUE, Hirayama disease) was first reported in 1959 as 'juvenile muscular atrophy of unilateral upper extremity'. Since then, similar patients in their teens or 20s have been described, under a variety of names, not only in Japan, but also in other Asian countries, as well as Europe and North America. Biomechanical abnormalities associated with JMADUE have recently been reported through various imaging examinations, proposing its disease mechanism. Since JMADUE differs from motor neuron disease, or spinal muscular atrophy, this disease entity should be more widely recognized, and early detection and effective treatments should be considered. We report an epidemiological study in Japan. Two nationwide questionnaire-based surveys, conducted in Japan from 1996 to 1998, identified 333 cases. The numbers of patients per year, distribution of ages at onset, mode of onset, time lapse between onset and quiescence, neurological signs and symptoms, imaging findings, and the effects of conservative treatments were analyzed. The peak age was 15 to 17 years, with a marked male preponderance, usually a slow onset and progression, and quiescence six or fewer years after onset. There was a predominantly unilateral hand and forearm involvement with 'cold paresis'. The imaging findings are described.

A cervical myelopathy with a Hirayama disease-like phenotype

A 21-year-old man with a muscular atrophy of the left distal upper extremity is presented. The disorder had been progressive over a few years, showing an exacerbation of the hand's weakness when the patient worked in a chilled environment (i.e., in a cold room). The patient's diagnostic work-up was extensive and the MRI documented the presence of a cervical myelopathy, associated to an inversion of the physiological lordosis at the C5-C6 level, with a phenotype highly resembling Hirayama disease. This case indirectly supports the debated hypothesis that juvenile amyotrophy of the upper limb (Hirayama disease) is actually a type of cervical myelopathy, with a likely ischaemic pathogenesis of the ventral horns.

Atopic myelitis with focal amyotrophy: a possible link to Hopkins syndrome

Among 22 consecutive patients with myelitis, of unknown etiology, and atopic diathesis (atopic myelitis) who from April 2002 to March 2006 had been studied in our clinic, 5 (23%) showed focal amyotrophy in one or two limbs. These 5 patients were subjected to combined clinical, electrophysiological, neuroimaging and immunological studies. Ages were 18 to 58-years-old (average 39). Four showed amyotrophy of unilateral or bilateral upper limbs while one showed amyotrophy in both thighs. All patients showed on-going denervation potentials in the affected muscles, while motor conduction study including F wave was normal except for in one patient who showed prolonged F wave latency in one nerve. Two had localized high signal intensity lesions involving anterior horns on spinal cord MRI and three showed abnormalities suggesting pyramidal tract involvement on motor evoked potentials. All had a present and/or past history of atopic disorders and specific IgE against common environmental allergens, such as mite antigens and cedar pollens, and four showed mild eosinophilia, all of which were compatible with atopic myelitis. When clinical and laboratory findings were compared between atopic myelitis with (n=5) or without focal amyotrophy (n=17), the former showed a significantly higher frequency of present and past history of asthma (80% vs. 24%, p=0.0393) and tended to have higher EDSS scores (3.8+/-1.6 vs. 3.1+/-1.4). Two patients showed mild to moderate improvements after immunotherapies such as methylprednisolone pulse therapy or plasma exchange, while two recovered with low dose corticosteroids and one without treatment had a gradually progressive course. Although atopic myelitis preferentially involves the posterior column of the cervical spinal cord, it is possible that anterior horn cells are affected in some cases of atopic myelitis, especially in patients with asthma. This suggests a possible link between atopic myelitis and Hopkins syndrome (asthmatic amyotrophy).