Hirayama in a kyudo archer: Tsuzuki 2021 case

This is the clinical history of a single boy, published by a Japanese neurology department. At 16, having joined his high school kyudo club in April, he held his neck rotated to the left towards the target during practice; he also had a habit of studying with his book on his knees and his head bent forward. In June his right shoulder became hard to lift, then both arms weakened until holding a rice bowl was a strain, and in August he was referred to hospital. On examination the deltoid, biceps and brachioradialis scored 3 out of 5 on both sides, the biceps and brachioradialis reflexes were absent, the leg reflexes were brisk with a bilateral Babinski sign, and there was mild loss of sensation on the radial side of both forearms.

MRI and CT myelography with the neck flexed showed the back wall of the dura moving forward and compressing the cervical cord from C3/4 to C6/7. This is the picture of Hirayama disease, in the rare form that affects the upper segments (C5 and C6) rather than those serving the forearm. To look at the role of the shooting posture, the authors repeated the myelography with the neck rotated to the left: the cord was still compressed and pushed forward and to the left, from C3/4 to C5/6, though less than in flexion.

Once kyudo was stopped and neck flexion and rotation were limited, sensation was almost normal within 2 weeks and arm strength recovered within 2 months, apart from slight biceps weakness. At 18 months strength and reflexes were normal, and there was no relapse up to the age of 20.

This is a single case report. The boy was assessed with a neurological examination and manual muscle testing, blood and cerebrospinal fluid tests (normal), neck X-rays in neutral and in flexion, MRI in neutral (also with contrast) and in flexion, and CT myelography in neutral, in flexion and in left rotation, the posture he held when shooting (a photograph in the paper shows it). Electromyography was not done, because the neurological signs already placed the problem in the spinal cord.

Treatment consisted of stopping kyudo, a cervical collar during the day and a low pillow at night, with advice to avoid neck flexion and rotation. He was followed for about four years. The paper is in Japanese, with figure captions in English.

A single case cannot say how often this happens or whether kyudo caused it. The boy had a kyphotic neck even in neutral, with its apex at C4/C5, and the authors think this is why rotation alone, without flexion, was enough to compress the cord. He also had a habit of studying for long periods with his head bent forward, which is the classic mechanism of the disease.

Rotation and flexion were restricted together, so the recovery cannot be credited to stopping archery alone. The rotated image was taken at rest, not during a draw with a bow in hand, and shows less compression than the flexed one. Finally, the literature the authors cite contains only one earlier paper on rotation in Hirayama disease, and there rotation with the neck in neutral did not compress the cord.

For almost every archer this case changes nothing: Hirayama disease is rare, mostly affects teenage boys, and here involved a neck whose curve was already abnormal. The head position in kyudo, as in other styles where the target is viewed side-on, involves a marked rotation held for several seconds on every arrow, and the case documents that in a predisposed neck that rotation can be enough to narrow the space around the cord.

For anyone coaching young beginners the useful detail is the course of events: shoulder weakness appearing within the first months of practice, in both arms and with altered reflexes, is a neurological picture rather than a technique problem, and the authors credit early diagnosis for this boy's full recovery. This record reports the case as a warning sign worth knowing, not as a risk of archery in general.