Charcot Marie Tooth

Question 1

What is Charcot Marie Tooth?

Answer 1

AKA Hereditary motor + sensory peripheral neuropathy

Not a single disease but a group of hereditary diseases of the PNS

• Inherited
• Neuropathy is the sole/ primary component
• Worsens over time
• Sensory + motor affected

Question 2

Case hx of a patient with Charcot Marie Tooth

Answer 2

45 year old man, presenting with bilateral stepping gait, foot numbness and difficulty with buttons.

Toe-walker from 13 months, unable to ice-skate as ankles weak. Began tripping and falling monthlly in 20s

Problems with hands started 5 years ago

Question 3

Charcot Marie Tooth epidemiology

Answer 3

1 in 2500 people

Question 4

Most common forms of Charcot Marie Tooth

Answer 4

CMT1 and CMT2

Question 5

Discuss Charcot Marie Tooth type 1

Answer 5

CMT1 affects the Schwann (rhymes)

CMT1 is the most common form (50% cases)

• Onset by 10yrs
• Mutation affected Schwann cells and myelin
• Muscle wasting in small muscles of hands + feet
• Spreads to legs and arms
• Foot drop, pes cavus

Question 6

Discuss Charcot Marie Tooth type 2

Answer 6

CMT2 affects axons

• Onset in 2nd decade
• Similar patterns of weakness in CMT1

Question 7

What is the overriding pathophysiology in Charcot Marie Tooth?

Answer 7

Hereditary diseases that cause defective production of proteins in the myelin shealth or neuronal axon

Question 8

Presentation of Charcot Marie Tooth

Answer 8

Muscular atrophy as motor nerves affected: weakness, foot drop, high-stepping gait

Walking difficulty

Pes cavus

Hyporeflexia

Reduced sensation

Toe walking

Question 9

Which muscles commonly atrophy in Charcot Marie Tooth?

Answer 9

Intrinsic muscles of hands and feet

Question 10

Foot deformities common in Charcot Marie Tooth

Answer 10

Hammer toes, toe walking, pes cavus, high stepping gait, foot drop, muscle atrophy

Question 11

Charcot Marie Tooth investigations

Answer 11

Nerve conduction: slowed conduction velocity

Genetic testing: mutations associated with specific CMT subtype

Nerve biopsy: repeated demyelination + remyelination (onion peel)

Question 12

Management of Charcot Marie Tooth

Answer 12

Physio + exercise

Bracing

Surgery for feet e.g. hammer toe straightening

Question 13

Prongosis of Charcot Marie Tooth

Answer 13

CMT1 = normal life expectancy

Other subtypes associated with reduced life expectancy