Neuromuscular disorders with its different types

The term neuromuscular disease defines disorders of the motor unit. The motor unit has four components:

1. A motor neuron in the brain stem or ventral horn of the spinal cord.
2. Its axon together with other axons.
3. The neuromuscular junction.
4. All muscle fibers innervated by a single motor neuron.
5. Clinical manifestations:
6. General features:
7. ● A prenatal history of decreased fetal movements and intrauterine growth retardation is often     found in patients who are symptomatic at birth.
8. ● Generalized hypotonia and delayed physical development are the most common presenting manifestations of neuromuscular diseases in infants and young children.
9. ● Head lag when an infant is pulled to a sitting position from supine is a sign of weakness.
10. ● Hypotonia may be associated with normal strength or with weakness.
11. ● Enlarged muscles may be weak “pseudohypertrophy” as in Duchene muscular dystrophy.
12. Tendon stretch reflexes are generally lost in neuropathies and are diminished but preserved in myopathies.
13. ● Fatigue and weakness are characteristic of neuromuscular disorders.
14. Specific features:
15.  are important in the diagnosis of some neuromuscular diseases:
16. ● Fasciculations of muscles which are often best seen in the tongue are a sign of    denervation as in Werding-Hoffmann disease.
17. ● Sensory abnormalities indicate neuropathy.
18. ● Hypertrophy of calf muscles in Duchenne myopthy with positive Gower’s maneuver.
19.  ● Some neuromuscular diseases are associated with cardiac abnormalities specially            
20.   cardiomypathy.

Investigations:

1. Electromyography (EMG):
2. Increased serum enzymes:
3. Nerve conduction velocity (NCV
4. Muscle biopsy.
5. Nerve biopsy.
6. Echocardiography in some cases, of cardiomyopathies
7. Molecular genetic markers.