Features of Hirayama Disease on Fully Flexed Position Cervical MRI

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.

Juvenile muscular atrophy of the distal upper extremity (Hirayama syndrome): a systematic review

INTRODUCTION

Hirayama syndrome is likely caused by a forward displacement of the posterior dura during cervical flexion leading to changes in the muscles of the fingers and wrist. The aim of this systematic review was to document the number of reported cases, the necessity of dynamic MRI of the cervical spine and the subsequent treatment.

METHODS AND MATERIALS

A systematic review was conducted and the Pubmed/Medbase, Cochrane, Google, Embase and Ovid database were searched for (Hirayama) AND ((disease) OR (syndrome)). A total of 42 studies were included for analysis reporting 2311 patients.

RESULTS

The mean age was 20.2 ± 2.26 years and predominantly males (92.8%) were identified. On MRI the "snake eyes" appearance of the spinal cord was present in 27.8% and the typical time between onset of symptoms and diagnosis was 41.5 ± 16.4 months. A variety of different treatments have been reported, although there is no substantial evidence that any of them are superior to observation.

CONCLUSION

The delay in diagnosis from initial presentation of symptoms shows that this condition may be underdiagnosed in a variety of cases. Further, this study shows the necessity of either a dynamic MRI in flexion or a static MRI scan in neutral position and in flexion, to identify functional spinal and/or foraminal stenosis for a prompt diagnosis and subsequent treatment.

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.

Polymyoclonus aggravated by neck flexion as the isolated presenting symptom of Hirayama disease: case report

Background

We report a rare case of an 18-year-old male with unilateral hand tremor who was finally diagnosed with Hirayama disease (HD).

Case presentation

An 18-year-old male presented with unilateral polymyoclonus that aggravated with neck flexion. The patient did not complain of muscle weakness or muscle atrophy. The needle electromyography showed giant motor unit potentials in right cervical 7 and 8 innervated muscles. The cervical magnetic resonance imaging on supine and flexion state showed prominent forward effacement of posterior dural sac that was compatible with HD.

Conclusions

HD usually presents with unilateral distal hand weakness, muscle atrophy and tremor. Although it is a benign and self-limiting disease, early diagnosis may lead to less clinical deterioration. Moreover, electromyography should be completed in the differentiation of young male patients who present with polymyoclonus without hand weakness or atrophy.

Is there cervical spine muscle weakness in patients with Hirayama disease? A morphological study about cross-sectional areas of muscles on MRI

PURPOSE

Patients with Hirayama disease (HD) present with a larger range of neck flexion and show signs of cervical spine instability. Cervical spine stability largely relies on cervical spine muscles. The purpose of this study was to compare the cross-sectional areas (CSAs) of cervical spine muscles between patients with HD and healthy controls, providing some insights into whether there is cervical spine muscle weakness and incongruence in HD patients.

METHODS

In this retrospective study, cervical spine muscles CSAs of 44 HD patients, as well as that of 44 age- and sex-matched healthy counterparts, were measured on the T2-weighted axial MR images. The ratios of cervical spine muscles CSA to the corresponding vertebral body areas, defined as R-CSAs, and the flexor/extensor CSA ratios were computed and compared between two groups.

RESULTS

Compared with healthy counterparts, R-CSAs of total cervical spine muscles, total extensors, superficial extensors, and deep flexors were significantly lower in HD patients. HD patients also demonstrated a significantly greater superficial flexor/superficial extensor CSA ratio than the healthy counterparts, indicating a mismatch between superficial flexors CSA and superficial extensors CSA in HD patients.

CONCLUSIONS

In this pioneering study, HD patients had decreased size in most cervical spine muscles and a mismatch between CSAs of superficial flexor and that of superficial extensors. These results indicate generalized weakness and incongruence of cervical spine muscles, which may predispose cervical spine of HD patients to a less stable situation. These slides can be retrieved under Electronic Supplementary Material.

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.

Hirayama disease: imaging profile of three cases emphasizing the role of flexion MRI

We report three cases of Hirayama disease, cervical flexion myelopathy presenting as unilateral or bilateral asymmetric muscular atrophy of forearm and hand involving C7 - T1 myotomes in young males. MRI revealed asymmetric cord atrophy, altered signal intensity of cord, posterior dural detachment and enlarged posterior epidural space with multiple flow voids. This article emphasizes the role of Flexion MRI in diagnosing Hirayama disease.

A severe case of Hirayama disease successfully treated by anterior cervical fusion

Hirayama disease, or juvenile amyotrophy of distal upper extremity, is a benign, self-limiting cervical myelopathy consisting of selective unilateral weakness of the hand and forearm. The weakness slowly progresses until spontaneous arrest occurs within 5 years of onset. The condition predominantly affects Asian males and is thought to be secondary to spinal cord compression during neck flexion, because of a forward displacement of the posterior dural sac.

The authors present what is to their knowledge the first reported case of a Caucasian male with a severe form of Hirayama disease, suffering from weakness of the leg as well as the forearm. An abnormal range of cervical flexion was observed at the C5–6 level. The patient was successfully treated by anterior cervical discectomy and fusion.

A Portuguese case of Hirayama disease

Hirayama disease, also known as monomelic amyotrophy or juvenile spinal muscular atrophy of the distal upper extremity features the impairment of the anterior horn cells of the distal cervical spinal cord secondary to dural sac anterior displacement during cervical flexion. We describe a case of a 17-year-old boy with a history of scoliosis, evaluated in the emergency department for decreased muscle strength and atrophy of the left upper limb with progressive worsening for about 6 months. We performed electrophysiological studies that showed severe neurogenic atrophy involving the C7-T1 left myotomes. Brain and spine MRI performed showed flattening of the lower cervical cord and dura mater anterior displacement during cervical flexion. These findings were consistent with the diagnosis of Hirayama disease.

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.