Hirayama disease in a young Indonesian male: a case report

Introduction

Hirayama disease (HD), also known as juvenile non-progressive amyotrophy or monomelic amyotrophy, is a rare, non-progressive lower motor neuron disorder. Patients typically present with muscular atrophy, progressing slowly over 2–5 years before stabilizing. Most commonly seen in males during their early to midteens (1), it is prevalent in Asian populations, with incidence rates of approximately 1 in 30,000 in Japan and 5.5 per 100,000 in South Korea (2). The pathogenetic mechanism centers on dynamic mechanical compression of the lower cervical spinal cord during neck flexion (3). It is hypothesized that disproportionate growth during puberty between the dural sac and vertebral canal leads to a tighter dural sac which when shifted anteriorly on neck flexion, causes ischemic injury to anterior horn cells (AHCs) (4). These patients typically present with unilateral or bilateral distal upper limb weakness, associated with cold paresis, hand tremors but an absence of sensory deficits or significant pain. The gold standard imaging for diagnosing HD is a dynamic magnetic resonance imaging (MRI) cervical spine in neutral and flexion positions. We report a case of HD involving the right upper limb and describe the MRI and electromyography (EMG) findings as well as discuss the management of this disease. We present this article in accordance with the CARE reporting checklist (available at https://jss.amegroups.com/article/view/10.21037/jss-2025-1-211/rc).

Case presentation

A 15-year-old male student presented on 27^th January 2025 with a 6-month history of right upper limb weakness with an insidious onset. He initially noticed neck soreness which progressively developed into difficulties in writing along with spasms of his hands. He did not complain of any numbness, muscle cramps, bowel/urinary incontinence or stiffness. He had no prior trauma, fever or exposure to toxic chemicals. There was also no family history of neuromuscular disease. On physical examination, there was atrophy of his right-hand muscles over the thenar eminence with weakness over his C6–T1 myotomes. His left upper limb and bilateral lower limbs had no neurological deficits. His gait and sensation were otherwise normal.

Nerve conduction study (NCS) showed no evidence of peripheral neuropathy or brachial plexopathy. The EMG suggested a purely motor neurogenic disease with ongoing denervation activities with spontaneous fasciculations over the right deltoid, biceps, extensor digitorum and first dorsal interosseous muscles. Interestingly, there was also spontaneous fasciculations recorded over the left deltoid (Table 1). There was a decrease in distal motor amplitude over the right wrist, forearm and elbow compared to the left (Table 2 and Figure 1).

Figure 1 Compound muscle action potential waves of patient’s upper limb.

An initial MRI cervical spine in neutral position was done on the day the patient presented which showed multilevel degenerative changes in the cervical spine with mild spinal canal stenosis but no cord compression or atrophy (Figure 2). As the initial MRI did not provide sufficient cause for the patient’s symptoms, further investigations were carried out. A dynamic MRI cervical spine in flexion was done 3 months later and showed mild reduction in overall volume with slight reduced caliber of cervical spinal cord from C5 down to T1 level. On flexion, it showed significant forward shifting/separation of posterior epidural sac in the lower cervical region (from C3 down to C6 level). Multiple prominent flow void tubular structures within the dilated posterior epidural space mainly seen in flexion (Figure 3). Upon neutral and slight extension, the displaced posterior epidural sac noted returns to its normal position (Figure 4).

Figure 2 Initial MRI cervical spine in neutral position. (A) Sagittal view; (B) axial view of C3/4; (C) axial view of C4/5; (D) axial view of C5/6. DDD, degenerative disc disease; MRI, magnetic resonance imaging.

Figure 3 MRI cervical spine in flexion. (A) Sagittal view; (B) axial view. The red circle denotes where forward shifting of the posterior epidural sac can be noted. MRI, magnetic resonance imaging.

Figure 4 MRI cervical spine in neutral. (A) Sagittal view; (B) axial view. MRI, magnetic resonance imaging.

Based on these findings, the diagnosis of HD was made. Patient was eventually treated conservatively with a hard cervical collar to limit neck flexion for 6 weeks with instructions to wear it at all times except bathing and eating. The patient was also given interval follow-ups for close monitoring. The patient was referred for physiotherapy and hand occupational therapy to for strengthening. After 6 weeks, the patient was transitioned from hard to soft collar to be used as required. At the 8-month follow up, the patient was compliant with the hard collar and his neurology was stable with no further worsening of his symptoms.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his legal guardian for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

HD is characterized by an insidious onset of asymmetrical weakness and atrophy in the distal upper limb with self-limiting nature. It has a higher prevalence among Asian males in their second decade of life (5). While HD is thought to be a self-limiting disease, patients may complain atypically of positive pyramidal signs, proximal upper limb atrophy, long irreversible progression or sensory deficits which can result in poor quality of life (3,6). In terms of its pathophysiology, it is believed to be due to an imbalanced growth between the patient’s vertebral column and the spinal canal contents, leading to a tight dural sac (7). With repeated neck flexion, the dura can be stripped off and become anteriorly displaced, resulting in loss of elastin fibers in the dura and engorgement of posterior epidural veins, which can cause ischemic compromise in the AHCs and increased cervical cord compression (8,9). The MRI plays a key role in clinching the diagnosis. As seen above, MRI cervical spine in neutral may show normal findings leading to a missed diagnosis. However, this case highlights the importance in imaging with neck flexion as this would then demonstrate hallmark findings of HD on the MRI cervical spine (10,11). Hallmark MRI findings in flexion would show anterior dural displacement, posterior epidural space dilation with flow voids, and segmental cord flattening/atrophy (“sand-watch” appearance) (12,13). Similarly, in a case by Kusel et al., an MRI in neutral position showed anteroposterior thinning of the cervical cord while flexion imaging showed ventral displacement of the dural sac with enlargement of the dorsal epidural space (14).

The use of EMG/NCS are also important in the diagnosis and differentiation of HD. An EMG would show segmental neurogenic damage of the AHCs in lower cervical spinal cord without disorders of the sensory nerves. Motor nerve conduction studies show decreased amplitudes and delayed latencies in the affected upper limb muscles without abnormal conduction velocities (3,15).

First-line treatment will be to apply a cervical collar to prevent neck flexion. Multiple studies have shown it to halt disease progression or even improvement in strength when applied early (16).

However, for patients responding poorly to conservative measures or those who are not compliant to a cervical collar, surgical intervention can be considered to provide stability by fixation (17). This would aim to relieve the compression of the cervical spine and restore normal cervical alignment. Surgical options can be divided into anterior cervical fusion and posterior cervical fixation/decompression surgery. While there are more reports describing the use of anterior cervical surgery for HD patients, there is a lack in studies demonstrating the superiority of either approach (18).

This case report is not without limitations. Firstly, due to its low occurrence in the population, the sample size of this case report is small which may limit meaningful conclusions in terms of management and its outcomes. Secondly, due to the retrospective design of this report, data for long term outcomes for this condition were not available. Lastly, this study did not compare outcomes of conservative versus surgical management options. Future studies could examine the long-term outcomes of this condition to help determine the impact and ramifications of different management choices.

Conclusions

Although HD is a rare and often self-limiting, early diagnosis is crucial to limit symptom progression. Simple conservative treatment with a cervical collar has shown to halt disease progression. The gold standard for diagnosis of this disease is an MRI cervical spine in flexion and extension. One of the hallmark features of this condition, both clinically and radiologically, is asymmetry. Hence, in adolescents presenting with progressive weakness of the distal upper limb, together with neurogenic changes on EMG and evidence of anterior displacement of the posterior epidural sac on flexion cervical spine MRI, HD should be considered.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://jss.amegroups.com/article/view/10.21037/jss-2025-1-211/rc

Peer Review File: Available at https://jss.amegroups.com/article/view/10.21037/jss-2025-1-211/prf

Funding: None.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jss.amegroups.com/article/view/10.21037/jss-2025-1-211/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from the patient and his legal guardian for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Al-Hashel JY, Abdelnabi EA, Ibrahim Ismail I. Monomelic Amyotrophy (Hirayama Disease): A Rare Case Report and Literature Review. Case Rep Neurol 2020;12:291-8. [Crossref] [PubMed]
2. Kim KE, Kim EJ, Kim K, et al. Prevalence of Neuromuscular Diseases in Young South Korean Males; A Korean Military Manpower Administration and Medical Command Data-Based Study. J Clin Neurol 2023;19:565-72. [Crossref] [PubMed]
3. Wang H, Tian Y, Wu J, et al. Update on the Pathogenesis, Clinical Diagnosis, and Treatment of Hirayama Disease. Front Neurol 2021;12:811943. [Crossref] [PubMed]
4. Baddam RR, Chadalavada B, Ambati N. A Case Report and Review of Literature on Hirayama Disease. Cureus 2024;16:e67627. [Crossref] [PubMed]
5. Goel A, Dhar A, Shah A. Multilevel Spinal Stabilization as a Treatment for Hirayama Disease: Report of an Experience with Five Cases. World Neurosurg 2017;99:186-91. [Crossref] [PubMed]
6. Orozco V, Gil A, Lancheros J, et al. Hirayama Disease: A Report of Two Cases and Review of Imaging Findings. J Radiol Med Imaging 2020;3:16.
7. Vengalil S, Boddu V, Kulanthaivelu K, et al. In-Depth Understanding of Hirayama Disease: Dural Detachment Beyond Cervical Spine. Ann Indian Acad Neurol 2025;28:574-8. [Crossref] [PubMed]
8. Gupta K, Sood S, Modi J, et al. Imaging in Hirayama disease. J Neurosci Rural Pract 2016;7:164-7. [Crossref] [PubMed]
9. Fukutake T. Hirayama Disease can be Caused by Loss of Attachment of the Cervical Posterior Dura to the Pedicle due to Immunological Abnormalities of the Dura and Posterior Ligaments: A New Hypothesis. Brain Nerve 2020;72:1371-81. [Crossref] [PubMed]
10. Kieser DC, Cox PJ, Kieser SCJ. Hirayama disease. Eur Spine J 2018;27:1201-6. [Crossref] [PubMed]
11. Paladi B, Amin D, Yarlagadda J, et al. Role of Dynamic Magnetic Resonance Imaging in Hirayama Disease, a Rare Motor Neuron Disease. Cureus 2022;14:e31099. [Crossref] [PubMed]
12. Boruah DK, Prakash A, Gogoi BB, et al. The Importance of Flexion MRI in Hirayama Disease with Special Reference to Laminodural Space Measurements. AJNR Am J Neuroradiol 2018;39:974-80. [Crossref] [PubMed]
13. Kaur R, Dua A, Gupta V, et al. Hirayama disease: neutral and flexion magnetic resonance imaging and utility of inter-segmental angle of flexion. Pol J Radiol 2022;87:e584-91. [Crossref] [PubMed]
14. Kusel K, Warne R, Lakshmanan R, et al. Hirayama disease: the importance of flexion imaging. BJR Case Rep 2022;8:20210105. [Crossref] [PubMed]
15. Ashhurst JF, Tan IL, Wang J. 3201 Case of hirayama disease with unusual neurophysiology. BMJ Neurol Open 2024;6:A12.
16. Vijayan SP, Gerber C, Basu A, et al. Hirayama Disease and Its Management: Experience of a Tertiary Care Center in Eastern India. Indian Spine J 2025;8:26-35.
17. Wang HL, Wu YW, Song J, et al. Cortical Activation Changes in Hirayama Disease After Anterior Cervical Decompression and Fusion. World Neurosurg 2018;116:e588-94. [Crossref] [PubMed]
18. Gao Y, Sun C, Ma X, et al. Do patients with Hirayama disease require surgical treatment? A review of the literature. Intractable Rare Dis Res 2022;11:173-9. [Crossref] [PubMed]