Neuromuscular Diseases

There are several "neuromuscular diseases", (diseases involving pathology of the nerves affecting muscular function), that can have a large impact on the foot and lower extremity.  We'll discuss several of the most common and well-known diseases:

Charcot Marie Tooth Disease  
    also known as CMT
    also known as Peroneal Muscular Atrophy
    also known as Familial Sensorimotor Polyneuropathy

Charcot Marie Tooth Disease is an inherited, progressive neuromuscular disease.  It affects men more than women by a ration of 5:1.   It involves a muscular atrophy of both the lower extremities (feet and legs) and upper extremities (hands and arms), and patients have a classic appearance of thin "stork" legs, high-arched "cavus" feet and hammertoes.  

Conservative treatment ranges from doing nothing in early or modest cases, to making special orthoses, toes splints, and AFO (ankle-foot-orthoses) braces.  Surgical intervention to address the hammertoes, high-arched feet, and muscular weakness is sometimes necessary.  

 Dejerine Sottas Disease    
    also known as Hypertrophic Interstitial Polyneuropathy

Dejerine Sottas Disease is clinically very similar to Charcot-Marie-Tooth Disease.  It, too, is characterized by muscle weakness in the legs and feet, high-arched "cavus" feet, and hammertoes, drop foot, and diminished sensation and reflexes.  Somewhat distinctive about Dejerine Sottas Disease is its tendency to cause visible enlargement of the nerves.  Diagnosis is by nerve biopsy.  

Treatment is the same as with Charcot-Marie-Tooth Disease.  

Friedreich's Ataxia

Symptoms with Friedreich's Ataxia also mimic Charcot-Marie-Tooth Disease (muscle weakness, cavus feet, hammertoes, drop foot, diminished reflexes and sensation), though Friedreich's Ataxia tends to strike earlier--in childhood.  Friedreich's Ataxia also progresses more rapidly and may lead to a greater degree of incapacitation by middle age.  There is also an increased tendency for heart problems (hypertrophic cardiomyopathy).  

Roussy-Levy Syndrome

Patients with Roussy-Levy Syndrome also have many of the same symptoms as Charcot-Marie-Tooth Disease, (muscle weakness, cavus feet, hammertoes, drop foot, diminished reflexes and sensation), though Roussy-Levy will commonly create tremors, particularly in the hands.  

Resfum's Disease

Resfum's Disease is a result of abnormal processing of the body's fats, causing huge increases in a compound known as phytanic acid.  As with the other disease mentioned above, Resfum's Disease may cause muscle weakness, cavus feet, hammertoes, drop foot, diminished sensation and reflexes, but patient's with Resfum's Disease also tend to develop ichthyosis (severe thickening of the outer layers of the skin) and night blindness.   The onset of Resfum's Disease is usually preceded by illness and high-fever.

Polio

Once a terrible scourge around the world, the polio virus affects the cells in the spinal cord, resulting in varying degrees of diminished reflexes, muscle wasting, weakness, and deformities in the lower extremity.  

Myelodysplasia (Spina Bifida)

Myelodysplasia is a spinal cord defect where portions of the spine protrude from their normal location in the spinal cord.  Myelodysplasia is most common in the lower lumbar and sacral vertebrae, which affects the nerves heading towards the feet.  Symptoms of these conditions include varying degrees of diminished sensation, diminished reflexes, poor muscular tone and balance, ulceration, and bladder dysfunction.   

There are four forms of myelodysplasia:

• Spina Bifida Occulta  In this, the mildest of cases, the bones of the spine have not formed properly, but the nerves of the spinal cord have not protruded from their normal location in the spinal canal.  

• Spina Bifida with Meningocele  In this case, the meningeal sac (covering the nerves) protrudes through the spinal cord, but remains covered by skin.  The nerves remain in their normal location.    

• Spina Bifida with Myelomeningocele  In this case, not just the sac has protruded--some of the nerves have protruded from the spine as well.  Again, the skin is closed over the defect.  

• Myelocele  In this, the most severe form, the nerve protrusion is not covered by the overlying skin.
  

Muscular Dystrophy (MD)

Muscular Dystrophy is a well-known disease characterized by muscle wasting, diminished reflexes, contractures of the feet and altered gait. Diagnosis is usually made by laboratory tests, electromyography, nerve conduction studies and muscle biopsy.  There are several types of Muscular Dystrophy with varying genetic causes, including:  

• Duchenne's Pseudohypertrophic Muscular Dystrophy is the most common form.  Affecting only males, usually in the 1-3 year-old age group, Duchenne's causes muscle weakness in the limbs' proximal muscles (those closest to the body), beginning in the legs, later affecting the arms.  Muscles appear larger because of increased presence of fat.  Gower's sign, (where the child rises from a sitting position by climbing up his legs), is a classic sign of this disease.  

• Becker's Muscular Dystrophy is similar to Duchenne's, but is a more benign form.  It is characterized by muscle weakness in the proximal muscles in the extremities (those closest to the center of the body).  

• Limb Girdle Muscular Dystrophy typically causes a tight calf muscles behind the leg (equinus) and high-arched feet, though sometimes flat feet are seen.  

• Facioscapulohumeral Muscular Dystrophy (Landouzy-Dejerine):  Characterized by the "Popeye the sailor" appearance in the forearms and a drop foot during the swing phase of gait.  
     

Cerebral Palsy (CP)

Cerebral Palsy is a non-progressive disease caused by a lesion in the cerebral portion of the brain.  The most frequent cause is from a period of diminished oxygen to a portion of the brain.  There are four forms:

• Spastic CP   Affecting nearly 2 out every 3 CP patients, Spastic CP is characterized by excessive reflexes.  It causes weakness in the muscles on the front of the leg, drop foot, a cavus foot, hammertoes and gait abnormalities. 

• Athetoid CP   Affecting roughly 20% of those with CP, Athetoid CP is characterized by writhing motions

• Ataxic CP   Affecting approximately 15% of those with CP, Ataxic CP is characterized by tremor and loss of muscle tone. 

• Rigid CP   Rare, Rigid CP is characterized by inflexibility.  

Tumours of the Spinal Cord

Tumours in the spinal cord may give a variety of symptoms in the lower extremities, depending upon where the lesion is located and which nerves are affected.