Hirayama disease: analysis of cases in Russia

Single-institution Series of Hirayama Disease in North America

STUDY DESIGN

A retrospective chart review.

OBJECTIVE

The aims of this study were to review pathophysiology, workup, and treatment for Hirayama disease (HD); and to assess outcomes from a single institution.

SUMMARY OF BACKGROUND DATA

HD is a rare, painless, cervical myelopathy with distal upper extremity weakness, muscle wasting, and spinal cord atrophy. Disease progression-a consequence of repeat flexion injury-occurs up to 5 years from the initial diagnosis.

METHODS

Single-institution review of pediatric HD patients from 2010 to 2020.

RESULTS

Patients (n=10 male, n=2 female) presented in the second decade (14-20 y) with painless progressive distal upper extremity weakness and atrophy without sensory loss. Electromyography (n=12) demonstrated denervation in C7-T1 myotomes and flexion/extension magnetic resonance imaging showed focal cord atrophy and anterior displacement of the posterior dura with epidural enhancement in flexion. Treatment included observation and external orthoses (n=9) and anterior cervical discectomy with fusion (n=3). One of the 9 patients managed conservatively experienced further deterioration; no patient who underwent anterior cervical discectomy with fusion progressed.

CONCLUSIONS

Patients with HD require a multidisciplinary approach to diagnosis and treatment to preserve function. Treatment is preventive and aims to minimize flexion injury by inhibiting motion across involved joints. First-line management is avoidance of neck flexion and use of rigid orthosis; in cases of failed conservative management and/or rapid clinical deterioration, surgical fixation can be offered.

Efficacy of Anterior Cervical Discectomy and Fusion for Female Patients with Hirayama Disease

OBJECTIVE

To compare the preoperative and postoperative hand function and radiographic parameters in female patients with Hirayama disease (HD).

METHODS

Consecutive female patients with HD undergoing anterior cervical discectomy and fusion were followed up. The postoperative hand functional data were obtained from the last follow-up, whereas the postoperative radiographic data were obtained from the examinations in 3- or 6-month follow-up after surgical treatments. The preoperative and postoperative data of hand functional and radiographic assessments were collected and compared between them. Logistic regression analysis was used to clear potential risk factors for surgical treatment.

RESULTS

In all, 15 female patients with HD were included in the follow-up study over 9 years. Significant differences were found in total scores (P < 0.001) and all 6 dimensions, including function (P = 0.003), activities of daily life (P = 0.002), work (P = 0.003), satisfaction (P = 0.002), appearance (P = 0.005), and HD-specific hand symptoms (P = 0.001) in hand functional assessment. The comparison of C2-C7 Cobb angle was statistically different (P = 0.042) in radiographic assessments. The course of illness was of marginal significance (P = 0.065) with curative effect of surgical treatment in logistic regression analysis.

CONCLUSIONS

Anterior cervical discectomy and fusion is an effective way to treat female patients with HD, and the course of illness may be correlated with the efficacy of surgery. For some female patients with HD with a clear diagnosis, early surgical treatment is worthy of clinical consideration.

The clinical characteristics of Hirayama disease in females

INTRODUCTION

To characterize Hirayama disease in female patients, and increase awareness among clinicians regarding the specifics of this disease.

METHODS

Baseline data, clinical manifestations, characteristics of cervical-flexion magnetic resonance imaging, and electromyography were collected and compared among females and males with Hirayama disease. In addition, the literature on Hirayama disease in females up to October, 2021 was searched in PubMed and the relevant data were compared with the data from our study.

RESULTS

Twenty female and 40 male patients were included in this study. The average ages of onset and menarche were 14.65 and 12.75 years old. All patients suffered from muscular weakness and atrophy of the upper limb(s), with flattening and/or atrophy of the lower cervical spinal cords in cervical-flexion magnetic resonance imaging, and neurogenic patterns in the atrophic muscles as determined using electromyography. The age of onset in females was about 2 years later than the age of menarche, and the age of onset in females was 2 years earlier than that in males. There were no obvious differences in clinical presentation between males and females.

DISCUSSION

Although females presented with Hirayama disease two years earlier than males, no other clinical differences were observed. Hirayama disease is likely associated with growth and development in puberty, and early identification, regardless of whether patients are male or female, is critical to optimizing prognosis.

Hirayama disease: the importance of flexion imaging

Hirayama disease is a rare cervical myelopathy characterised by asymmetrical upper limb weakness and muscle atrophy in the forearm and hand. MRI of the cervical spine plays an essential role in diagnosis, however, the characteristic findings are often only seen when the patient is imaged with the neck in flexion.

We present a case of a 15-year-old male who presented with left forearm and hand weakness with muscle wasting. An MRI of the cervical spine with the neck in a neutral position demonstrated atrophy of the spinal cord with intrinsic signal abnormality between C5 and C7. Further imaging with the patient’s neck in flexion demonstrated the hallmark features of Hirayama disease. There was anterior displacement of the thecal sac and spinal cord, and an enlarged, crescent-shaped dorsal epidural space which enhanced following i.v. gadolinium administration. The atrophic segment of cord contacted the posterior vertebral bodies when the neck was in full flexion. This case highlights the importance of imaging patients suspected of having this entity with the neck in full flexion in order to make a diagnosis.

Interobserver and Intraobserver Reproducibility and Reliability of the Huashan Clinical Classification System for Hirayama Disease

Purpose: The Huashan clinical classification system for Hirayama disease has recently been proposed and has been found useful for diagnosis and treatment. So far, however, there has been little in-depth evaluation of its reliability. Thus, this study aimed to assess the reproducibility and reliability of the system. Methods: Patients diagnosed with Hirayama disease between 2019 and 2020 were recruited. Seven spine surgeons from four different institutions, including an experienced group of three and an inexperienced group of four, were trained as observers of the Huashan clinical classification system for Hirayama disease, and these surgeons classified the recruited patients using the system. Then, 2 months later, they repeated the classification on the same patients in a different order. The interobserver and intraobserver agreement between the results was analyzed using percentage agreement and weighted kappa (κ) statistics. Results: A total of 60 patients were included in the analysis. For all the observers, experienced observers, and inexperienced observers, the agreement percentages were, respectively, 78.5% (κ = 0.76), 80.0% (κ = 0.78), and 78.9% (κ = 0.77), indicating substantial interobserver reproducibility. For distinguishing typical (Types I and II) and atypical (Type III) Hirayama disease among the different groups of observers, the percentage agreement ranged from 95.6 to 98.9% (κ = 0.74-0.92), indicating substantial to nearly perfect reproducibility. For suggesting conservative treatment (Types I and III) or surgery (Type II), the percentage agreement ranged from 93.3 to 96.4% (κ = 0.81-0.90), indicating nearly perfect reproducibility. As for intraobserver agreement, the percentage agreement ranged from 68.3 to 81.7% (κ = 0.65-0.79), indicating substantial reliability. Conclusion: The Huashan clinical classification system for Hirayama disease was easy to learn and apply in a clinical environment, showing excellent reproducibility and reliability. Therefore, it would be promising to apply and promote this system for the precise and individualized future treatment of Hirayama disease.

Transcranial Magnetic Stimulation-Induced Motor Evoked Potentials in Hirayama Disease: Systematic Review of the Literature

PURPOSE

Hirayama disease (HD) is a rare motor disorder mainly affecting young men, characterized by atrophy and unilateral weakness of forearm and hand muscles corresponding to a C7-T1 myotome distribution. The progression is self-limited. The etiology of HD is unclear. The usefulness of motor evoked potentials (MEPs) in pyramidal tracts damage evaluation still appears to be somehow equivocal.

METHODS

We searched PubMed for original articles, evaluating the use of transcranial magnetic stimulation elicited MEPs in HD using keywords "motor evoked potentials Hirayama" and "transcranial magnetic stimulation Hirayama."

RESULTS

We found seven articles using the above keywords that met inclusion criteria. The number of participants was small, and diagnostic procedures varied. There were also differences in methodology. Abnormal central motor conduction time was found in 17.1% of patients in one study, whereas it was normal in two other studies. Peripheral motor latency was evaluated in one study, which found abnormally increased peripheral motor latencies in at least one tested muscle in 16 of 41 HD patients (39.0%). Abnormal MEP parameters were found in three studies in 14.3% to 100% patients. In one study they were not evaluated, in three other studies they were normal, and in one they were normal also in standard and flexed neck position In one study, inconsistent results were found in MEP size after neck flexion in patients after treatment with neck collar.

CONCLUSIONS

Although MEP parameters may be abnormal in some HD patients, these have not been thoroughly assessed. Further studies are indispensable to evaluate their usefulness in assessing pyramidal tract damage in HD.