Results: Clinical Orthopaedics and Related Research

Results: Clinical Orthopaedics and Related Research
Complications of Surgery of the Foot and Ankle in Hereditary Neurologic
Disorders
ISSN: 0009-921XAccession: 00003086-200110000-00019Full Text (PDF) 99 K
Author(s):

Roy, Dennis R. MD; Al-Sayyad, Mohammed Jalal MD

Issue:Volume 391, October 2001, pp 181-187

Publication Type:[SECTION I SYMPOSIUM: Complications in Foot and Ankle
Surgeries]

Publisher:(C) 2001 Lippincott Williams & Wilkins, Inc.

Institution(s):From the Children's Hospital Medical Center, Cincinnati, OH.
Reprint requests to Dennis R. Roy, MD, Children's Hospital Medical Center,
3333
Burnet Avenue, Cincinnati, OH 45229.

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Outline

Abstract

Presentation

Pathogenesis of Deformity

Physical Evaluation

Imaging

Treatment

Complications

References

Section Description

Graphics

Table 1
Table 2

Abstract

The hereditary motor and sensory neuropathies are one of a group of
hereditary
neurologic disorders. Patients with these disorders initially may present
with a
deformity of the feet and toes. Complications in the treatment of these
deformities can be minimized by a proper diagnosis, identifying the
components
of the deformity, and selecting the appropriate procedure(s). Correcting
the
muscle imbalance and the deformity will be necessary in most patients and
most
patients will require a combination of surgical procedures.
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Muscle and nerve disorders frequently are accompanied by orthopaedic
conditions.
Deformities of the feet and toes often are the first manifestation of an
underlying neuromuscular disorder. The most common lower extremity
deformity
seen is that of a cavus or cavovarus foot. Failure to diagnosis the
etiology of
the cavus deformity is a complication because it may compromise early
treatment
and lead to inappropriate treatment. Proper diagnosis generally can be made
by
family history, clinical examination, and electrodiagnostic studies.
Consultation
by a neurologist may facilitate the work-up and obtaining a diagnosis. The
hereditary neurologic disorders are a heterogeneous group of inherited
disorders
whose classification has undergone significant revision because more
information
has become available on nerve and muscle physiology, clinical features,
natural
history, genetic transmission, and specific gene abnormalities. 15,21
Included
in this diverse group are the hereditary motor and sensory neuropathies,
the
hereditary sensory and autonomic neuropathies (familial dysautonomia and
congenital insensitivity to pain), spinal cerebellar degeneration
(Friedreich's
ataxia), and spinal muscular atrophy. It is important to make a specific
diagnosis before the treatment of a deformity because the risk of prognosis
may
vary and influence treatment. The current study will emphasize the
hereditary
motor and sensory neuropathies group of disorders (Table 1).
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TABLE 1. Hereditary Motor Sensory Neuropathies
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Charcot-Marie-Tooth disease, as the prototype disorder in hereditary motor
and
sensory neuropathies, is a group of inherited diseases of the peripheral
nerve
that present with similar manifestations. As reported by Mendell, 15 the
disorder was described independently in 1886 by Charcot and Marie of France
and
Tooth of England. Its prevalence rate is one in 2500 but its true incidence
probably is more frequent because of the heterogeneity of the disorder(s).
These
disorders have autosomal dominant, autosomal recessive, and x-linked modes
of
inheritance. There currently are at least four types of Charcot-Marie-Tooth
disease and an x-linked form, which are differentiated by age of onset,
clinical
examination, and electrophysiologic findings. Adding to this heterogeneity
are
two related neuropathies; hereditary neuropathy with liability to pressure
palsies and congenital hypomyelination syndrome. 15 Three genes encoding
for
myelin proteins (peripheral myelin protein 22[PMP-22], myelin protein 0,
Connexon 32) and one gene for a nuclear protein (early growth response 2)
on
chromosomes 1, 10, and 17 have been associated with Charcot-Marie-Tooth
disease
and its related forms. 21

Hereditary sensory and motor neuropathies Type I is the classic
hypertrophic
demyelinating form of Charcot-Marie-Tooth disease. It is inherited as an
autosomal dominant trait with an onset in the first or second decade of
life.
Significant slowing of the nerve conduction velocity is a typical feature.
Nerve
enlargement is a clinical feature including the greater auricular, ulnar,
peroneal, and superficial radial nerves. Hereditary neuropathy with
liability to
pressure palsies, 15 a genetically-related neuropathy to Charcot-Marie-
Tooth
disease, often is misdiagnosed as Charcot-Marie-Tooth disease Type I. It is
inherited as an autosomal dominant disorder whose onset is in the second or
third decade of life. It generally presents as a mononeuropathy, such as
peroneal palsy or carpal tunnel syndrome, which may follow minimal trauma.
Caution must be taken when doing surgery on these patients to avoid
traction on
peripheral nerves and to avoid the use of a tourniquet. Hereditary motor
and
sensory neuropathies Type II or the neuronal form of Charcot-Marie-Tooth
disease
also is inherited as an autosomal dominant trait presenting in the second
decade
of life or later. A subtype of Type II includes vocal cord paralysis and
respiratory muscle weakness. Hereditary motor and sensory neuropathies Type
III,
originally described by Dejerine and Sottas in 1893 as reported by Mendell
15 is
transmitted by autosomal recessive inheritance. It is a severe
demyelinating
neuropathy characterized by early, often newborn, onset. Infants often are
hypotonic and delayed motor milestones may be apparent in infancy or early
childhood.

The four additional types of hereditary motor and sensory neuropathies tend
to
be a late onset and occur in adults. Hereditary motor and sensory
neuropathies
Type IV or Refsum's disease is associated with elevated serum levels of
phytanic
acid and has autosomal recessive inheritance. Hereditary motor and sensory
neuropathies Type V is a spastic paraplegia that usually presents in the
second
decade of life or later. The patients have distal weakness in the limbs and
generally present with an awkward gait and foot deformities. It is
inherited as
an autosomal dominant trait. Hereditary motor and sensory neuropathies Type
VI
is similar to Type I with optic nerve atrophy. Finally, hereditary motor
and
sensory neuropathies Type VII also is similar to Type I, but associated
with
retinitis pigmentosa. 15

Presentation

The common deformity of this diverse group of hereditary neurologic
disorders is
the cavus foot. Foot and ankle symptoms frequently cause the patient to
first
seek medical attention. Complaints at the time of presentation include
weakness,
pain, ankle instability, tender callosities, deformity (cavus and claw
toes),
and difficulty with shoewear. The cavus deformity presents as a spectrum
ranging
from the mild cavus foot with flexible claw toes to the severely rigid
deformity
and painful foot.

Pathogenesis of Deformity

In the hereditary motor and sensory neuropathies group, the cavus is
produced by
muscle imbalance involving the intrinsic and extrinsic muscle of the foot.
The
pathogenesis of the cavus deformity in Charcot-Marie-Tooth disease has been
reported by several authors 1,5,11,13 and seems to be secondary to the
weakness
of the tibialis anterior, peroneus brevis, and the intrinsic muscles with
retained strength in the peroneus longus and tibialis posterior. The weak
tibialis anterior is overpowered by the peroneus longus, which results in
plantar flexion of the first ray and the medial side of the foot. The weak
peroneus brevis is overpowered by a strong tibialis posterior adducting and
leading to an inverted varus position of the forefoot. As the plantar
aponeurosis
and intrinsic muscles contract, deformity becomes more rigid and
progressive. A
clawtoe deformity results from dorsiflexion at the metatarsophalangeal
joints by
the toe extensors, which is accentuated by the unopposed normal long toe
flexors. The clawtoe deformity often is accentuated during the swing phase
of
gait, because the long toe extensors attempt to act as accessory
dorsiflexors of
the ankle. The muscular weakness combined with the varus deformity produces
significant instability at the ankle. With the varus position, the
transverse
tarsal and calcaneal cuboid joints become locked and there is decreased
ability
of the foot to dissipate force at heel strike. This effect and the change
in the
weightbearing surface of the foot produces increased pressure along the
lateral
border of the foot causing complaints of discomfort.

Physical Evaluation

On examination of the patient with hereditary motor and sensory
neuropathies
Type I or classic Charcot-Marie-Tooth disease, there is a variable amount
of
distal muscle weakness and atrophy. The classic inverted champagne bottle
shaped
legs or stork legs is not always present. Bilateral cavus feet are present
often
with clawing of the toes. A careful examination should be done to determine
individual muscle strength and to evaluate the deformity and its components
for
rigidity. Examination of the foot in the weightbearing position and in the
nonweightbearing position will give valuable information. The deformity
typically consists of a varus hindfoot, forefoot, midfoot or hindfoot
cavus, and
forefoot equinus or valgus (caused primarily by plantar flexion of the
first
metatarsal). Callosities beneath the metatarsal heads and at the base of
the
fifth metatarsal should be seen. Contracture of the tendoachilles is
measured
focusing on the motion of the calcaneus and not on the forefoot, which
remains
in equinus. Hindfoot flexibility is determined by the lateral Coleman block
test
as reported by Paulos et al. 16 This