Introduction: Hirayama firstly reported (1959) a disorder of the juvenile age (11-25 years), characterized by unilateral or asymmetric slowly progressive amyotrophy of the distal upper extremity. The initial progressive course is followed by a spontaneous arrest. Named Hirayama Disease (HD) or Monomyelic Amyotrophy or Cervical Flexion Myelopathy (CFM), proposed by Kikuchi basing to the possible etiology: a compression of the cervical spinal cord during neck flexion. Etiology is still debated. The value of conservative or surgical treatments has not been established: collar therapy, cervical arthrodesis, cervical duroplasty – laminoplasty and muscolotendineous transfer have been proposed.
Methods: The clinical and radiographic characteristics of 15 patients affected by CFM were examined. Mean age at onset was 16 years, with a male prevalence (13/15), as already reported. Nine were operated by expansive duraplasty and suspension in combination with laminotomy. Neutral and fully flexed neck positions MRI and neurophysiologic exams were performed before and after. The remaining 6 cases were managed conservatively. Neutral and fully flexed neck MRI showed posterior dural loss of attachment and cervical spinal cord flattening . One out of 8 operated cases experienced transient worsening, despite surgery one progressed and then stabilized, while in the remaining patients progression stopped Venous engorgement, presumed by MRI, was documented at surgery in all the cases, as well as spinal cord tendency to herniate by the dural opening; in 1 case there was also arachnoid adhesion.
Results: In our series of HD patients clinical diagnosis was confirmed by dynamic MRI, confirming the importance of neck flexion for proper diagnosis.
Conclusions: The early diagnosis is a milestone because clinical outcome may be strikingly improved by early surgery. If rapidly progressive disease occurs a surgical treatment may be considered before the spontaneous arrest, whilst mild HD may have a conservative approach.
Patient Care: 1. increasing the diagnosis of HD
2. defining the coorect surgical treatment for HD
Learning Objectives: 1. diagnose the rare HD
2. indications for surgery in HD