Duraplasty with laminoplasty for Hirayama disease: a technical note with a case series

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Asian Spine J. 2025;19(4):631-637

Publication date (electronic) : 2025 June 24

doi : https://doi.org/10.31616/asj.2024.0451

Fadlyansyah Farid^1,2, Toshio Nakamae¹, Yoshinori Fujimoto³, Kiyotaka Yamada³, Yasushi Fujiwara⁴, Hiroki Fukui¹, Nobuo Adachi¹

¹Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan

²Departement of Orthopaedic and Traumatology, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia

³Department of Orthopaedic Surgery, JA Hiroshima General Hospital, Hiroshima, Japan

⁴Orthopedics and Micro-Surgical Spine Center, Hiroshima City North Medical Center Asa Citizens Hospital, Hiroshima, Japan

Corresponding author: Toshio Nakamae, Department of Orthopaedic Surgery, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima, 734-8551, Japan, Tel: +81-82-257-5232, Fax: +81-82-257-5234, E-mail: toshinakamae623813@yahoo.co.jp

Received 2024 November 28; Revised 2025 January 26; Accepted 2025 February 18.

Abstract

GRAPHICAL ABSTRACT

Introduction

Hirayama et al. [1] first described Hirayama disease in 20 patients with juvenile muscular atrophy of the unilateral upper extremity. Characteristic features included predominantly young men, unilateral muscle atrophy in the intrinsic and flexor muscles of the forearm, tremor-like finger movements, and finger weakness easily triggered by exposure to cold environments [2–24].

The diagnosis of Hirayama disease is based primarily on clinical findings. Imaging of the spine is used to determine pathology and is an important role in diagnostics and guiding treatment decisions. Plain radiography, computed tomography (CT) with myelography, and magnetic resonance imaging (MRI) are modalities for better diagnosis. In other studies, Hirayama disease has been considered a type of cervical flexion myelopathy [2,4,5,9,17].

The treatment of Hirayama disease remains challenging, and the optimal surgical approach for patients with this disease is controversial. We retrospectively analyzed the clinical features and neuroradiological and imaging findings of patients who underwent surgery for Hirayama disease, focusing on duraplasty with laminoplasty. We investigated the surgical outcomes of duraplasty with laminoplasty for Hirayama disease.

Technical Notes

Patients

We analyzed the data of patients with Hirayama disease who underwent duraplasty with laminoplasty between 1996 and 2022 at our three facilities with a minimum follow-up period of 5 years. The inclusion criteria were as follows: patients with symptomatic Hirayama disease in advanced stages who failed to respond to conservative treatment (e.g., neck collar) to prevent neck flexion. Hirayama disease in advanced stages was diagnosed based on the following: (1) MRI and myelogram taken in the neutral neck position showing no spinal cord compression (with or without intramedullary signal change on MRI) and, in a flexed position, showing compression of the dura and spinal cord with an anterior shifting of the dorsal dura mater (Fig. 1); and (2) the progression of symptoms of distal muscle atrophy of the upper limbs. We excluded patients with spinal cord atrophy even in the neutral neck position and those with spinal cord tumors, hand diseases, or other neurological conditions. Patient characteristics, including age, sex, grip strength, preoperative clinical symptoms (e.g., muscle atrophy and tremor-like movements), duration of the preoperative period, and follow-up periods, were evaluated. The severity of disability in activities of daily living was classified into three degrees using the Tokumaru classification as follows [2,25]: Severity I: Grip strength of the affected hand was maintained at ≥50% of the unaffected side; Severity II: Grip strength of the affected hand was decreased to <50% but >30% of the unaffected side; and Severity III: Grip strength of the affected hand was decreased to <30% of the unaffected side [2,25].

Fig. 1

Magnetic resonance imaging (MRI) and computed tomography (CT) myelogram taken with the neck in a neutral position showed no spinal cord compression on T2-weighted MRI: T2-weighted sagittal MRI (A); T2-weighted axial MRI (B); sagittal image of CT myelogram (C); and axial image of CT myelogram (D). MRI and CT myelogram taken with the neck in a flexion position showed that the spinal cord was compressed, shifting the dorsal dura mater anteriorly: T2-weighted sagittal MRI (E); T2-weighted axial MRI (F); sagittal image of CT myelogram (G); and axial image of CT myelogram (H). (I) Illustrations highlighting the spinal cord compression with the neck in a flexion position. CSF, cerebrospinal fluid.

Main outcomes

Table 1 presents the characteristics of the five patients who underwent duraplasty with laminoplasty. All patients were male, with an average age of 17.4 years (range, 17–18 years). Four patients exhibited pathological features on their left upper extremity, and one patient had symptoms on the right upper extremity. The affected side had lower grip strength than the contralateral side. All patients were followed up for neurological improvements, such as tremor-like symptoms and numbness improvement. The dysesthesia in the upper extremities disappeared after cervical duraplasty with laminoplasty. Histologically, the dura mater appeared abnormal, lacking the normal wavy structure of the elastic fibers. Tokumaru classification improvement was observed, with preoperative scores shifting from one patient with Severity II and four with Severity III to three patients with Severity I and two with Severity II postoperatively. Complications associated with the surgery occurred in two patients: intraoperative bleeding from the congested epidural venous plexus requiring blood transfusion in one patient and cerebrospinal fluid leakage requiring spinal drainage in the other patient.

Table 1

Patient characteristics

Illustrative case (case no. 4 in Table 1)

An 18-year-old man presented with numbness on the ulnar side of his left hand and motor weakness in his left hand for 3 months. No symptoms were observed in the right or lower extremities. Grip strength testing revealed 30 kg on the right hand and 19 kg on the left hand. The patient had muscular atrophy in his left hand, particularly in the hypothenar muscles (Fig. 2). CT myelogram and MRI performed with the neck in the neutral position revealed no spinal cord compression (Fig. 3). When the neck was flexed, the spinal cord was significantly compressed on the left side, and the dorsal dura mater shifted anteriorly (Fig. 4). The patient underwent cervical duraplasty with laminoplasty using a surgical microscope and intraoperative neuromonitoring (Fig. 5). Severe epidural venous plexus congestion was observed after lamina opening (Fig. 5A). Hemostasis was achieved carefully using an irrigation bipolar coagulator. After transverse dissection of the dura mater to preserve the arachnoid membrane (Fig. 5B), the incision of the dura mater gradually expanded (Fig. 5C). Subsequently, when the cervical spine position was changed intraoperatively from a neutral to a flexed position, the dural incision expanded further. The defect of the dura mater was repaired with water tightly using an artificial dura mater patch (Fig. 5D). One year after the surgery, the patient’s numbness and motor weakness in the left hand had improved. Postoperative MRI with the neck flexed revealed no spinal cord compression or anterior shift of the dorsal dura mater (Fig. 6).

Fig. 2

Clinical presentation of thenar muscle atrophy.

Fig. 3

Magnetic resonance imaging (MRI) and computed tomography (CT) myelogram taken with the neck in a neutral position showed no spinal cord compression on T2-weighted MRI: T2-weighted sagittal MRI (A); T2-weighted axial MRI (B); sagittal image of CT myelogram (C); and axial image of CT myelogram (D).

Fig. 4

Magnetic resonance imaging (MRI) and computed tomography (CT) myelogram taken with the neck in a flexion position showed that the spinal cord was compressed, shifting the dorsal dura mater anteriorly: T2-weighted sagittal MRI (A); T2-weighted axial MRI (B); sagittal image of CT myelogram (C); axial image of CT myelogram (D).

Fig. 5

Surgical view under the operating microscope. (A) Severe congestion of epidural venous plexus is observed after lamina opening. (B) After transverse dissection of the dura mater, the arachnoid membrane is preserved. (C) After transverse dissection of the dura mater preserving the arachnoid membrane, the incision of the dura mater gradually expands. (D) The dura mater defect is repaired water tightly using an artificial dura mater.

Fig. 6

Postoperative magnetic resonance imaging (MRI) with the neck in a flexion position. Postoperative MRI with the neck in a flexion position showed no spinal cord compression and no anterior shift of the dorsal dura mater: T2-weighted sagittal MRI (A) and T2-weighted axial MRI (B).

Discussion

Hirayama disease, a rare disorder with an unclear etiology, manifests uniquely at a young age. Scientific reports on Hirayama disease are scarce worldwide. According to a review paper by Bäcker et al. [23], only 42 studies on Hirayama disease have been published to date. Several theories have been proposed regarding the mechanics of Hirayama disease, which is decisive for diagnosis because some believe that disproportionate growth can cause advanced myelopathy [4,18]. Fujimoto et al. [2] reported that this disease results from dural tightness, engorged vertebral venous plexus, and atrophy of the anterior horns of the spinal cord. Dural tightness, resulting from stretching in an up–down direction owing to growth imbalance between the long cervical spine and short spinal cord, can lead to anterior horn impairment, potentially disrupting intramedullary circulation [2]. The pathophysiology of Hirayama disease may involve ischemic necrosis of the anterior horn of the spinal cord, and Hirayama disease can be classified as a type of cervical flexion myelopathy [2,4,5,9,17,27]. Furthermore, cervical flexion myelopathy can present with both white matter lesions and anterior horn syndrome [2]. Based on our study, dural tightness may represent the main pathophysiology of Hirayama disease, as evidenced by the improvement in patient symptoms following duraplasty.

Several therapeutic options, both conservative and surgical, exist for Hirayama disease treatment. For conservative treatment, cervical orthosis is still used in many mild cases to prevent neck flexion [28]. Duraplasty with or without fusion is effective [4,11,17], although opinions diverge on the need for fusion, particularly in patients with alignment disorders [13]. However, other studies have reported that duraplasty with and without fusion can still be performed using strict patient selection considerations [14]. We advocate posterior cervical laminoplasty and duraplasty to preserve motion in young patients with early-stage Hirayama disease. This technique is based on a tight dural canal during neck flexion, as reported by Konno et al. [11], who successfully treated patients with Hirayama disease using this technique with good results. This was reinforced by Fujimoto et al. [2], who performed duraplasty with good outcomes without postoperative complications, such as kyphosis and pseudomeningocele. Anterior cervical discectomy and fusion with a plate has been reported as the most commonly used surgical method for treating Hirayama disease [15,18,23]. Although fusion surgery can prevent cervical physiological flexion and has shown improvement in symptoms of Hirayama disease, it is important, particularly for young patients, to preserve the motion segment considering their long lifespan. Hilibrand et al. [29] reported that 25%–89% of patients exhibited degenerative changes at adjacent levels after a long-term follow-up study of cervical arthrodesis. Cervical duraplasty with laminoplasty prevented abnormal forward displacement of the dorsal dura mater during neck flexion while preserving the normal range of motion of the cervical spine without major surgical complications. The clinical improvements achieved using our method provide evidence that a tight dura mater during flexion significantly contributes to the occurrence of symptoms in patients with Hirayama disease.

In our approach for treating Hirayama disease, we initially performed conservative treatments, such as using a cervical collar, in cases with progressive symptoms in the early stage of the disease [28]. If conservative treatment is ineffective, we proceed with surgical intervention. In particular, in cases in which MRI or CT myelography in a flexed position revealed spinal cord compression due to anterior shifting of the dorsal dura mater, we first performed duraplasty with laminoplasty. If symptoms continue to progress after duraplasty with laminoplasty, fusion surgery may be appropriate. Furthermore, for cases showing spinal cord atrophy on MRI or CT myelography in a neutral position and no spinal cord compression in a flexed position MRI or CT myelography but having impairments of activities of daily living, we performed musculotendinous transfer in the late stage of Hirayama disease. In any case, early diagnosis of Hirayama disease is crucial for determining the appropriate treatment.

Limitations include the analysis of a small sample size and the lack of a control group; therefore, multicenter case–control studies are necessary. Despite these limitations, duraplasty combined with laminoplasty has been proposed as an effective treatment for advanced-stage Hirayama disease. This surgical approach decompresses the spinal cord by expanding the dural sheath while preserving cervical motion.

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