Charcot-Marie-Tooth disease

—MC inherited neurological disorder

—1886 described together

—Professor Jean Martin Charcot and his student Pierre Marie – Peroneal Muscular Atrophy

—Howard Henry Tooth – Peroneal Progressive Muscular Atrophy. Attributed it correctly to neuropathy.

—1912 Hoffman described peroneal muscular atrophy with thickened nerve; Hoffman’s disease.

—Hereditary Sensory and Motor Neuropathy type I, II and III (Dejerine-Sotta’s disease)

Classification

—Type 1

—Demyelinating;

—further subdivided A (MC, 70%), B & C.

—Autosomal dominant

—Type 2

—Axonal degeneration;

—Autosomal dominant or recessive

—Type C

—Intermediate between axonal degeneration and demyelinating

—Autosomal dominant

—Clinical Features

—Incidence of all types of CMT varies from 1 in 5000 to 1 in 2500

—Presents with

—Progressive weakness and atrophy of distal muscles

—Depressed DTRs

—Slowed nerve conduction velocities

—Family h/o similar disease

—Varied age of onset

—Most commonly onset at the 2nd decade of life

—CMT Type 2 onset 3rd decade of life

—Normal motor milestone

—Incidence equal in both sexes, severity more in boys with CMTX

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—Physical signs

•Diminished to absent DTRs

—Ankle jerk lost before knee jerk

—Sensory loss

—2/3rd of the patients

—More common in CMT 1 than CMT 2

—Muscular weakness

—Varied involvement of muscle

—MC muscles involved are tibialis anterior and peroneus brevis. May involve all the muscles of the calf

—Most severe form – generalized muscle weakness → inability to walk

—Atrophy of calf muscles → stork leg appearance

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—Gait changes

—Early stages – slight foot drop seen only in swing phase

—Progressively develop complete plantigrade foot with hyperflexion of knee then hip and elevation of hemipelvis

—Steppage gait

—Foot deformity

—Pes cavus, pes cavovarus or claw toe

—Hands show atrophy of intrinsic muscles

—Progressive scoliosis of spine seen in adolescent and teens

—Sensorineural deafness maybe seen in CMTX.

—Investigations

—Blood tests – known mutations

—EMG-NCV

—Demyelinating: decrease in velocity with amplitude same as normal

—Axonal degeneration: same velocity with decrease amplitude

—EMG shows fibrillation due to denervation

—Nerve Biopsy

—Sural nerve is used

—Demyelinating – Onion Bulb appearance

—Type 2 – Axonal degeneration

—Muscle biopsy – atrophic muscles

—MRI Spine

—Diffuse enlargement of cauda equina, nerve roots and ganglia

—Sonography

—Enlargement of median nerve

—Medical management

—No medical treatment to slow or stop the disease

—71% of the patients present with severe neuropathic pain requiring medications

—Orthopaedic manifestations

—Foot

—MC manifestation is pes cavovarus

—Atrophy due to denervation of the intrinsic muscles → contractures → elevation of the medial longitudinal arch because of the contracture of plantar fascia

—Plantar flexion of the first ray and forefoot equinus → varus of the hind foot

—Claw toes – absent intrinsic muscles

—

—Radiographs

—Meary’s angle

—Angle between the longitudinal axis of talus and the 1st metatarsal

—Normal 0-5°

—Coleman’s block test

—Patient made to stand on a block of wood with the 1st metatarsal head falling off the block

—Supple hind foot varus – corrects

—Fixed varus – does not correct

—Surgical management

—Olney divided surgical management into two components

—Deformity correction

—Soft tissue release

—Plantar fascia release

—Capsulotomies

—Bony fusions or osteotomies

—1st metatarsal osteotomy

—Calcaneal osteotomy

—Triple arthrodesis

—

—Rebalancing of muscle forces

—Tendon transfers

—Dorsiflexion weakness – EDL or posterior tibial transfer

—Overpowering peroneus longus – transfer to peroneus brevis

—Hindfoot equinus – tendoachilles lengthening

—

—Claw toes

—Paralyses and contracture of intrinsic muscles

—Toe extensors recruited to dorsiflex ankle

—Jones transfer of the long extensors to the metatarsal to help ankle dorsiflexion

—Fusion of IP joint of great toe and PIP joint of the other toes

—Hip

—Dysplasia of hip

—Subtle weakness of the proximal musculature → progressive dysplasia of hip

—Asymptomatic till adolescent

—Treatment similar to idiopathic adolescent dysplasia of hip

—Spine

—Scoliosis seen in 37%

—Similar to idiopathic scoliosis with increased kyphosis

—Highest risk in girls & CMT 1

—May present with hyperkyphosis without scoliosis

—Treatment

—Orthosis

—Posterior spinal fusion – failure of orthotic management and with progressive curves

—Hand

—Onset of hand symptoms occur in 1st to 3rd decade of life; 8 years after the appearance of lower limb symptoms

—Present with intrinsic muscle weakness with clawing of ring and small digits occur.

—Involvement of ulnar and median nerve innervated forearm and intrinsic muscles

—Sparing of radial nerve innervated muscles

—Functional problems:

—Loss of opposition

—Loss of side to side pinch

—Clawing of fingers

—Management

—Electrodiagnostic studies done to determine the best muscle for tendon transfer

—Transfers without pulley or if required with static pulley preferred to tendon or tendon loop pulley

—Opponensplasty – extensor carpi ulnaris or extensor indicisproprius

—Side to side pinch – extensor pollicis brevis, abductor pollicislongus or extensor indicis to 1st dorsal interosseous or adductor pollicis

—Muscle transfer done in flexion of MCP joints to compensate extrinsic extensors

—

—Delayed till age when patient can understand the limitations and aftercare

—The disease and deformity can be progressive

—Transfer requires protection from excessive abuse

—Dejerine-Sottas Disease
(Hypertrophic Interstitial Neuritis)

—Severe, infantile-onset demyelinating polyneuropathy

—Related to same gene as CMT 1A

—Enlarged peripheral nerves – proliferation of perineural and endoneural tissues

—Classical onion bulb appearance

—Presenting complaint

—Disability of gait under 3 years of age

—Floppy muscles, thickened nerves.

—Severe cases present with respiratory failure at birth.

—Similar findings as CMT with increased severity and earlier age of onset.

—No treatment

—Steroids can be given in severe cases.

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