Question

Case Study:

An 8-year-old boy was presented for difficulty in walking and muscle weakness with difficulty in climbing stairs, running and particularly in vigorous physical activities, he also had decreased strength and endurance. His parents did not have consanguineous marriage, one brother and two sisters were all healthy; no other family members were similarly affected. On examination, he had difficulty jumping onto the examination table, a Gower sign, proximal weakness of pectoral and pelvic girdle muscles, a waddling gait tight hell cords, and apparently enlarged calf muscles. His serum creatine kinase and aldolase levels were 50 fold higher than normal, motor nerve conduction studies revealed low amplitude compound muscle action potentials throughout, with normal conduction velocities.

Question: How would you differentiate this disease from one of the disease listed below, which also produce muscle weakness? MS

Answer 1

The child is suffering from Duchenne Muscular dystrophy (DMD).

Duchenne muscular dystrophy is characterised by progressive degeneration of muscle fibres causing muscle weakness and loss of muscle mass. Duchenne muscular dystrophy exhibits muscle weakness starting proximally, initially affecting shoulder girdle and pelvic muscles. Muscle tightness and pseudohypertrophy of muscles is seen. DMD affects the male population. It causes difficulty in walking and performing other ADLs due to muscle weakness.

In the above case following findings show that the boy is suffering from DMD :

• Positive Gowers sign due to weakness of pelvic girdle muscle
• Increased creatinine kinase and aldolase due to muscle fibre degeneration
• Enlarged calf muscles showing pseudohypertrophy
• Normal conduction velocity due to intact nerve supply to muscles
• Waddling gait due to muscle weakness

Multiple sclerosis is a demyelinating disease of central nervous system. It is a disease of middle age mainly affecting people from age group of 20-50 years. It results in demyelination of the nerve cells. The disease is characterised by lesions of the myelin sheath known as sclerae. The disease shows relapsing and remitting course. The symptoms include sensory and motor impairments, autonomic dysfunction and psychiatric problems. The disease is characterised by impaired nerve conduction velocities and positive lhermittes sign ( bending of neck produces a feeling of passing of electric current)

All these above features distinguish MS from muscular dystrophy. Thus we can say that the child is suffering from DMD.