J Korean Radiol Soc.  2003 May;48(5):379-385. 10.3348/jkrs.2003.48.5.379.

MRI Findings of Nonprogressive Juvenile Spinal Muscular Atrophy of the Distal Upper Limbs (Hirayama's Disease)

• Lee IS
• Lee TH
• Kim HJ
• Song JW
• Lee SH
• Choi KD
• Park KP
• Choi KB

• KMID: 1833674
• DOI: http://doi.org/10.3348/jkrs.2003.48.5.379

Abstract

PURPOSE
The aim of this study was to describe the dynamic changes of the cervical dural sac and the spinal cord during neck flexion in patients suffering from Hirayama's disease and to present the usefulness of flexion MR study for the diagnosis.
MATERIALS AND METHODS
Seven consecutive male patients (age ranging 17-43 years, mean age 23.7 years) with the clinical diagnosis of Hirayama's disease and 5 healthy subjects (aged 25-32 years) for controls had done cervical MRI from January 2001 through June 2002. Cervical MRI was done in neutral and neck flexed positions using 1.5 T system (Sonata, Siemens, Germany) and obtained images were reviewed by two radiologists. We compared the cervical MRI findings of 7 patients with those of 5 healthy controls regarding neck flexion induced changes in the lower cervical segments.
RESULTS
Neutral positioned cervical sagittal MR images revealed subtle or mild cord atrophy in only 2 patients. On maximal neck flexion, AP diameter of the cresent posterior epidural space was increased and also cord flattening with anterior shifting of posterior wall of the lower cervical dural canal was noted in all 7 patients. In all 7 cases, the level and side of spinal cord changes corresponded to the clinical phenotype. All control subjects showed neither cord flattening nor widening of posterior epidural space on neck flexion.
CONCLUSION
In patients with the clinical diagnosis of Hirayama's disease, MRI scans obtained on maximal neck flexion showed characteristically dynamic flattening of lower cervical cord and widening of posterior epidural space. Therefore, a flexion MR study is needed to prove the diagnosis.

Keyword

Muscular atrophy, spinal; Muscular atrophy; Spinal muscular atrophies of childhood

MeSH Terms

Atrophy
Diagnosis
Epidural Space
Humans
Magnetic Resonance Imaging*
Male
Muscular Atrophy
Muscular Atrophy, Spinal
Neck
Phenotype
Spinal Cord
Spinal Muscular Atrophies of Childhood*
Upper Extremity*