A Rare Case of Myopathy

A young Saudi lady presented with gradual worsening of muscle weakness and skeletal stiffness. Her sister has a similar condition. The clinical picture was very consistent with diagnosis of Rigid Spine Syndrome. This impression was further substantiated by the result of muscle biopsy. This syndrome was not clearly understood and probably not so rare either. This negative picture was basically imposed by under reporting and lack of large studies.


Introduction
Rigid Spine Syndrome [RSS] is relatively new disease consisting mainly of proximal muscle weakness as an initial presenting feature1.Later on the disease evolve leading to progressive limitation of trunk and neck movement.Various means of inheritance 2 and histological patterns had been described 3 .Beside its effect on movement the syndrome usually cause skeletal deformity which ultimately jeopardize breathing and may cause serious cardiac arrhythmias 4 .
This may be the first case from Saudi Arabia and other Arab countries.
A19 year young Saudi lady presented with progressive shortness of breathing for some years.She was born normally after full term pregnancy.Early in her childhood she was noted to have limited mobility of the neck otherwise had normal milestones till she was eight years old, when she started to develop progressive kyphosoliosis, muscular weakness and atrophy.This gradually affected her mobility then breathing over the years.When seen she could only walk few steps using Zimmer's frame and connected to a portable home ventilator from which she can wean herself maximally one hour a day.She had spinal surgery in attempt to rectify her kyphosoliosis in a reputable center in USA but unfortunately with little success.
Nevertheless with this limitation, this young lady has attended school with excellent academic results emphasizing the supportive role of the family.Her elder sister has a similar problem with severe kyphosoliosis and muscle weakness but was less handicapped as she could walk unaided and needed the ventilator only during sleep.
Her paternal grandmother had limited mobility of her neck but the rest of the family members were normal.

Discussion:
In the seventies when Dr. Dubowitz described the first recognized case of rigid spine syndrome, he called it a new myop for name 1 .Subsequently other cases were reported from different parts of the world 2,5 know this was the first case to be reported from Saudi Arabia and the rest of arab countries.The mode of inheritance of this syndrome coul autosomal dominant or recessive with variable penetrance 2 as demonstrated by our case history.It usually presents with muscle weakness which commonly involves the distal muscles, but the proximal groups may also be affected.Breathing is usually affected due to kyphoscoliosis.However, serious consequences will arise when respiratory muscles become involved.Patients could easily develop type 2 respiratory failure following chest infections Muscle biopsy usually shows protean histological features like increase of inclusion bodies in the cell cytoplasm some muscles necrosis with fibrosis, other feature in disproportion of the muscle fibers e.g increase in type I and lack of type II fibres 5,6 .
Because different ways of presentation were described, it has been suggested that the rigid spine syndrome may represent different patterns of diseases rather than a single entity.Examples of the various ways of presentations are fatal cardiomyopathy 7 , selective respiratory muscles involvement with relative sparing of other muscles group.Other rare feature is the association with enzymatic deficiency like acid maltose 8 .Like most other myopathies specific treatment is not available and management is largely supportive.The prognosis depends on the severity of muscle and other organs involvements.

Conclusion
This syndrome is probably more common than people think.Its true nature and etiology remains unclear which emphasize the need for further research.

Fig.
Fig. Muscle biopsy showing mixture of atrophic muscle fibres and cytoplasmic vacuolations.The connective tissue is not increased (EVG 400x)