- Email: [email protected]
Charcot Marie Tooth Disease
ADULT PATHOLOGY
Charcot Marie Tooth Disease
(Box 1). In general they are classified by their inheritance pattern and which part of the nerve cell is affected. CMT can either be autosomal dominant, recessive or X-linked. These genetic abnormalities affect gene expression for vital proteins in myelin sheaths, peripheral nerve cell axons, or sometimes both. It is the large variety of genetic abnormalities on each chromosome resulting in CMT that has resulted in the ever-increasing recognition of subtypes.
DWJ Howcroft S Kumar N Makwana
Clinical history The onset of symptoms can be variable, depending on the type, but is often during adolescence or early adulthood. Research has shown that children as young as 2 years of age show electrical evidence of nerve dysfunction in CMT-1,1 without any clinical signs. CMT affects both upper and lower limbs, but usually affects the lower legs first. Patients may present with increasing deformity, a history of recurrent ankle sprains, or the development of a high stepping (foot drop) gait (the latter being rare). In the early stages of CMT foot drop may occur with fatigue, at the end of the day. Alternatively, sufferers may
Abstract Charcot Marie Tooth (CMT) disease was first described in 1886. It describes a spectrum of genetic disorders that affects peripheral nerves, either by slowing action potential transmission along the axons, or by reducing the amplitude, or both. It is this variety of underlying genetic findings and subtleties of clinical presentation that has resulted in the varying nomenclature over the years. Patients with CMT commonly present to orthopaedic surgeons with lower and upper limb symptoms including ankle sprains, cavus feet and weakness of the intrinsic hand muscles. More rarely, they present with spinal and hip manifestations. It is not usually a life threatening or painful condition and therefore lends itself to the FRCS (Tr & Orth) exam.
CMT types and subtypes
Keywords Charcot Marie Tooth (CMT); Hereditary Motor Sensory Neuropathy (HMSN)
CMT1 (50%) C Myelin sheath abnormality C Autosomal dominant C Further division into CMT1A,B,C, etc. C CMT1A e duplication of PMP* 22 on chromosome 17
Introduction
CMT2 (20e40%) C Abnormal peripheral nerve cell axons C Autosomal dominant
It was in Paris in 1886 that Jean-Martin Charcot and his student Pierre Marie described the clinical manifestations of CMT. They initially attributed this to a myelopathy, but it was Henry Tooth from Cambridge, later in the same year, who correctly recognised this to be due to a dysfunction of peripheral nerves. It is the most common genetic neurological condition. Though there is no known cure, it is usually painless and only rarely fatal.
CMT3 (rare) C Dejerine-Sottas disease C Specific point mutation of PMP 22 or P(0) gene C Severe demyelinating disease affecting infants and children
Epidemiology CMT4 (rare) C Several subtypes C Genetic basis not yet fully understood C Demyelinating disease C Autosomal recessive C Childhood leg weakness, non-ambulatory by adolescence
CMT appears to affect all races equally. The global prevalence is thought to be in the region of 1 in 2500e3500 people. A total of 2.6 million people probably suffer from CMT worldwide. There is often a strong genetic component with CMT so that a positive family history can be very helpful in diagnosis. It is recognised that patients can develop CMT despite a negative family history by spontaneous genetic mutations. The incidence of this is not known. Other terms, such as ‘‘Peroneal Muscle Atrophy’’, have been used previously, making a detailed review of management over the years difficult.
CMTX (10e20%) C Connexin-32 gene affected C Schwann cells affected C Males moderate to severely affected C Females mild or no symptoms
Classification Over the last decade numerous types and subtypes of CMT, which affects both motor and sensory nerves, have been described genetically
Intermediate CMT (rare) C Autosomal dominant C Myelin AND axons affected
DWJ Howcroft MBBS iMRCS is a Specialist Registrar at Wrexham Maelor Hospital, 24 School Drive, Lymm, Cheshire, UK.
HNPP C Hereditary Neuropathy with predisposition to Pressure Palsy C Closely related to CMT1 C Deletion instead of duplication C Episodic, recurrent demyelinating neuropathy
S Kumar MBBS iMRCS is a Core Trainee 2 at Wrexham Maelor Hospital, Croesnewydd Road, Wrexham, UK. N Makwana MBBS FRCS (Tr & Orth) is a Consultant Foot & Ankle Orthopaedic Surgeon at Wrexham Maelor Hospital, Croesnewydd Road, Wrexham, UK and Robert Jones & Agnes Hunt Hospital, Oswestry, UK.
ORTHOPAEDICS AND TRAUMA 23:4
Box 1
274
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
have noticed that their feet (cavus, occasionally planus) or toes (clawing) have changed shape. This is almost always bilateral. They, too, may complain of ‘‘pins and needles’’ and sometimes pain, in upper and lower extremities as well as clumsiness and weakness of the hands. In children, parents may say children are clumsy or inactive. Though generally considered painless, neuropathic pain is seen in CMT. This appears to be under-reported.2 A detailed family history in these patients is important. On discovering these progressive feet abnormalities it is always worth considering the differential diagnoses, particularly in cavus feet (Table 1).
of the hindfoot (Figure 2) which should be considered before deciding upon treatment. By standing the patient on a block at the angle shown, the 1st ray can be offloaded and the hindfoot can then be assessed for full or partial correction of its apparent varus.7 Occasionally the lesser metatarsals may also be depressed, which means a slight modification of the Coleman block test (i.e. angle the foot so the lesser metatarsal heads are also offloaded).
Diagnosis Once the above history and findings have suggested a diagnosis of CMT, a number of further tests can be used to confirm it. These consist of electrophysiological and genetic assessmen, and occasionally nerve biopsy.
Clinical examination The classical appearances of ‘‘inverted champagne bottle’’ legs with pes cavus and hammer toes (Table 2) are not always present, but should be sought. Specific distal lower limb muscle wasting should be assessed and MRC graded power in these groups should be documented. Deep tendon reflexes are commonly diminished or absent. Patients may have sensory ataxia, resulting in a positive Rhomberg’s test. It is not uncommon to be able to palpate thickened posterior auricular nerves, and some patients may also develop sensorineural deafness. Patients usually don’t perceive sensory deficit, but formal testing can elicit diminished proprioception and vibration sense, and later problems with pain and temperature may be encountered. Other orthopaedic manifestations of CMT include hip dysplasia3 and scoliosis, the incidence of which is approximately 25%, but this depends on the CMT type, with CMT-1 appearing to predispose most strongly to spinal deformity.4
Electrophysiology Nerve conduction velocities and amplitudes are tested for reductions of either or both. Electromyography is also performed to assess which muscle groups are affected, and to what extent. CMT1 usually exhibits reduced velocities (abnormal myelin) and normal amplitudes. CMT2 demonstrates normal velocities but reduced ampli tudes (dysfunctional axons). Other forms can manifest with a variety of combinations of the above. Genetic testing Only some forms of CMT1 can be recognised by this means. May be useful for patients concerned about transmission to offspring.
Pathophysiology The pattern of weakness in the distal leg muscles in CMT is characteristic. There is a critical distribution of muscles affected which results in the classical deformity. The anterior compartment is principally affected, while in the lateral compartment the peroneus brevis is more severely affected than the longus.5,6 The intrinsics are weak; these are usually the first muscles affected in the hand too. Clawing of the lesser toes is due to weakness of the intrinsic muscles and relative sparing of the extrinsics. The cavus foot, in part, is produced by extension contractures of the metatarso-phalangeal joints, causing tightening of the plantar fascia, but more importantly by the relatively intact peroneus longus muscle plantarflexing the first ray by overpowering the weakened tibialis anterior. This in turn contributes to the varus of the hindfoot, further exaggerated by the action of tibialis posterior, which is relatively unopposed because of the more weakened peroneus brevis muscle. Figure 1 illustrates a classical pattern of deformity seen in CMT. The hindfoot varus is usually correctable, often until late in the disease. The ‘‘Coleman block test’’ is useful in assessing this flexibility
Nerve biopsy Outdated practice Rarely used
Potential causes of Cavus Foot Neuromuscular C Peripheral neuropathy e CMT C Spinal cord disease e poliomyelitis, neoplasia, syringomyelia. C CNS disease e Freidrich’s ataxia, cerebral palsy C Myopathy e muscular dystrophy Congenital C Arthrogryposis C Residual clubfoot deformity Trauma C Post compartment syndrome Idiopathic Figure 1 Classical appearance in the lower legs in a patient with Charcot Marie Tooth Disease.
Table 1
ORTHOPAEDICS AND TRAUMA 23:4
275
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
Operative The surgical treatment of CMT foot deformity tends to follow a stepwise approach that may include:
soft tissue procedures osteotomies arthrodeses. The principle of treatment is to align the foot under the tibia and the sole flat to the ground. The muscles around the foot are then balanced. Orthoses may still be needed. In general, soft tissue procedures are reserved for children, osteotomies and soft tissue procedures are beneficial in adults, and fusions should be reserved for the older patient with degenerative changes and/or deformity. There is no agreement on the timing of surgical intervention, but generally the soft-tissue procedures and osteotomies are best performed in mobile joints, and the arthrodesis reserved for more severe fixed deformities.
Figure 2 Correction of hindfoot varus with Coleman Block Test.
C C C C C C
C
Soft tissue procedures The philosophy of these procedures is to use the relatively spared muscles to bolster those that are most severely affected. The weak peroneus brevis predisposes to ankle instability and the relatively preserved peroneus longus muscle tends to promote the cavus deformity. By transferring the longus to the brevis both problems may be lessened. The Jones procedure may be useful. EHL is detached from the hallux and transferred to the neck of the first metatarsal, often with a synchronous fusion of the interphalangeal joint. This allows the EHL to dorsiflex the ankle, without worsening of the claw deformity. It sometimes needs to be supplemented with a closing wedge osteotomy of the first metatarsal to allow full correction. There is little evidence to show that these procedures delay the onset of more severe deformity. Plantar fascial release proximally is no longer recommended.
Often genetic transmission Affects motor and sensory nerves Upper and lower limbs affected History of unsteadiness/clumsiness and ankle sprain Classical pattern of nerves involved Lower limbs more severely affected B inverted champagne bottle legs B cavus feet with hammer toes Clumsiness and intrinsics wasting most common findings in upper limbs
Osteotomies These are usually used when the majority of the deformities are correctable but one or two are not. For example, a dorsiflexion closing wedge osteotomy at the base of the first metatarsal may be used if fixed plantarflexion at the first ray has occurred. Alternatively various calcaneal osteotomies may be use to correct heel position in fixed situations, or allow lateralisation of the tendo achilles (TA).
Table 2
Management
Arthrodeses Triple arthrodesis is the most widely used skeletal procedure for the fixed cavovarus foot. Evidence suggests that the operation produces good long-term results10 although others have reported that over three quarters of CMT patients experience only fair to poor results at 20 years.11 It is thought that the main reason for this is recurrence of deformity and the development of ankle degenerate change. Many patients go on to require pantalar athrodesis. Due to the risk of recurrent deformity, particularly with fusions in the young patient, most advocate the use of soft tissue balancing procedures in combination with fusion (Table 3).
As already discussed, CMT is a progressive disease and as yet there is no known cure. Management of these patients is aimed at keeping them mobile and independent for as long as possible. It is influenced by symptoms and the extent to which the patient complains, whether from footwear problems, ankle instability, pain, ulcers or stress fractures.
Non-operative Lifestyle factors, such as reducing weight and keeping fit, can help ensure patient mobility. Patients should also avoid drugs that can potentiate neuropathy, such as nitrofurantoin, isoniazid and also alcohol to excess. The mainstay of non-operative treatment involves a combination of keeping the joints supple with regular stretches and a resort to static and dynamic bracing. Though useful in controlling symptoms. Evidence is unconvincing regarding improvement,8 and most reports suggest it makes no difference.9 In the early stages regular stretching of the calf is useful, and simple ankle supports may reduce the incidence of ankle sprains. Once more severe foot- drop occurs lightweight ankle-foot-orthoses (AFOs) with assisted dorsiflexion can be used. Later. when the deformities are more pronounced, patients often need specifically moulded AFOs. Devices are available that appear to maintain movement and muscle bulk by electric stimulation. These threshold electrical stimulation machines are not widely used and there is to date no evidence supporting their use.
ORTHOPAEDICS AND TRAUMA 23:4
Treatment of CMT Non-operative C weight loss C avoidance of certain drugs C accommodative footwear C simple bracing C AFO Operative C soft tissues/tendon transfers C osteotomies (midfoot and hindfoot) C arthrodeses Table 3
276
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
Summary Charcot-Marie-Tooth disease remains a very challenging condition to treat. As no cure exists at present the mainstay of treatment is to maintain mobility and independence. Though affecting both upper and lower limbs, it is the legs that are usually more severely affected and often require orthotic or surgical treatment. Other manifestations, such as hip dysplasia and scoliosis, may require surgery if symptomatic or progressive. Surgical treatment remains a challenge as there is very little strong evidence to support the different options, and complications and recurrence of deformity are relatively common. It is clear that genetic or medical management remains the only hope for a true cure. Bracing and surgery only provide symptomatic relief and a slight improvement in gait. Genetic counselling should be offered for all patients affected with CMT, thus giving a clear idea of the risks of inheritance. A
5 6
7 8
9
10 REFERENCES 1 Berciano J, Garcia A, Calleja J, Combarros O. Clinicoelectrophysiological correlation of extensor digitorum brevis muscle atrophy in children with Charcot Marie Tooth disease 1A duplication. Neuromuscul Disord 2000; 10: 419e24. 2 Carter GT, Jenson MP, Galer BS, et al. Neuropathic pain in CharcotMarie-Tooth disease. Arch Phys Med Rehabil 1998; 79(12): 1560e4. 3 Walker JL, Nelson KR, Heavilon JA. Hip abnormalities in childrenwith Charcot-Marie-Tooth diease. J Pediatr Orthop 1994; 14: 54e9. 4 Horacek O, Mazanec R, Morris CE, Kobeova A. Spinal deformities in hereditary motor and sensory neuropathy: a retrospective
ORTHOPAEDICS AND TRAUMA 23:4
11
qualitative, quantitative, genotypical, and familial analysis of 175 patients. Spine 2007; 32(22): 2502e8. Mann RA, Missirian J. Pathophysiology of Charcot-Marie-Tooth disease. Clin Orthop 1998; 234: 221e8. Tynan MC, Klenerman L, Helliwell TR, Edwards RH, Hayward M. Investigation of muscle imbalence in the leg in symptomatic forefoot pes cavus: a multidisciplinary study. Foot Ankle 1992; 13: 489e501. Coleman SS, Chestnut WJ. A simple test for hindfoot flexibility in the cavovarus foot. Clin Ortop Relat Res 1977; 123: 60e2. Guzian MC, Bensoussan L, Viton JM. Orthopaedic shoes improve gait in Charcot-Marie-Tooth patient: a combined clinical and quantified case study. Prosthet Orthot Int 2006; 30(1): 87e96. Refshauge KM, Raymond J, Nicholson G. Night splinting does not increase ankle range of motion in people with Charcot-Marie-Tooth disease: a randomised, cross-over trial. Aust J Physiother 2006; 52(3): 193e9. Saltzman CL, Fehrle MJ, Cooper RR. Triple arthrodesis: twenty-five and forty-four year average follow-up of the same patients. J Bone Joint Surg Am 1999; 81(10): 1391e402. Wetmore RS, Drennan JC. Long-term results of triple arthrodesis in Charcot-Marie-Tooth disease. J Bone Joint Surg Am 1989; 71: 417e22.
Acknowledgement With thanks to Mr. P Cooke MB,ChB,FRCS,ChM, Consultant Orthopaedic Surgeon, Nuffield Orthopaedic NHS Centre, Oxford.
277
Ó 2009 Elsevier Ltd. All rights reserved.
Charcot Marie Tooth Disease
(Box 1). In general they are classified by their inheritance pattern and which part of the nerve cell is affected. CMT can either be autosomal dominant, recessive or X-linked. These genetic abnormalities affect gene expression for vital proteins in myelin sheaths, peripheral nerve cell axons, or sometimes both. It is the large variety of genetic abnormalities on each chromosome resulting in CMT that has resulted in the ever-increasing recognition of subtypes.
DWJ Howcroft S Kumar N Makwana
Clinical history The onset of symptoms can be variable, depending on the type, but is often during adolescence or early adulthood. Research has shown that children as young as 2 years of age show electrical evidence of nerve dysfunction in CMT-1,1 without any clinical signs. CMT affects both upper and lower limbs, but usually affects the lower legs first. Patients may present with increasing deformity, a history of recurrent ankle sprains, or the development of a high stepping (foot drop) gait (the latter being rare). In the early stages of CMT foot drop may occur with fatigue, at the end of the day. Alternatively, sufferers may
Abstract Charcot Marie Tooth (CMT) disease was first described in 1886. It describes a spectrum of genetic disorders that affects peripheral nerves, either by slowing action potential transmission along the axons, or by reducing the amplitude, or both. It is this variety of underlying genetic findings and subtleties of clinical presentation that has resulted in the varying nomenclature over the years. Patients with CMT commonly present to orthopaedic surgeons with lower and upper limb symptoms including ankle sprains, cavus feet and weakness of the intrinsic hand muscles. More rarely, they present with spinal and hip manifestations. It is not usually a life threatening or painful condition and therefore lends itself to the FRCS (Tr & Orth) exam.
CMT types and subtypes
Keywords Charcot Marie Tooth (CMT); Hereditary Motor Sensory Neuropathy (HMSN)
CMT1 (50%) C Myelin sheath abnormality C Autosomal dominant C Further division into CMT1A,B,C, etc. C CMT1A e duplication of PMP* 22 on chromosome 17
Introduction
CMT2 (20e40%) C Abnormal peripheral nerve cell axons C Autosomal dominant
It was in Paris in 1886 that Jean-Martin Charcot and his student Pierre Marie described the clinical manifestations of CMT. They initially attributed this to a myelopathy, but it was Henry Tooth from Cambridge, later in the same year, who correctly recognised this to be due to a dysfunction of peripheral nerves. It is the most common genetic neurological condition. Though there is no known cure, it is usually painless and only rarely fatal.
CMT3 (rare) C Dejerine-Sottas disease C Specific point mutation of PMP 22 or P(0) gene C Severe demyelinating disease affecting infants and children
Epidemiology CMT4 (rare) C Several subtypes C Genetic basis not yet fully understood C Demyelinating disease C Autosomal recessive C Childhood leg weakness, non-ambulatory by adolescence
CMT appears to affect all races equally. The global prevalence is thought to be in the region of 1 in 2500e3500 people. A total of 2.6 million people probably suffer from CMT worldwide. There is often a strong genetic component with CMT so that a positive family history can be very helpful in diagnosis. It is recognised that patients can develop CMT despite a negative family history by spontaneous genetic mutations. The incidence of this is not known. Other terms, such as ‘‘Peroneal Muscle Atrophy’’, have been used previously, making a detailed review of management over the years difficult.
CMTX (10e20%) C Connexin-32 gene affected C Schwann cells affected C Males moderate to severely affected C Females mild or no symptoms
Classification Over the last decade numerous types and subtypes of CMT, which affects both motor and sensory nerves, have been described genetically
Intermediate CMT (rare) C Autosomal dominant C Myelin AND axons affected
DWJ Howcroft MBBS iMRCS is a Specialist Registrar at Wrexham Maelor Hospital, 24 School Drive, Lymm, Cheshire, UK.
HNPP C Hereditary Neuropathy with predisposition to Pressure Palsy C Closely related to CMT1 C Deletion instead of duplication C Episodic, recurrent demyelinating neuropathy
S Kumar MBBS iMRCS is a Core Trainee 2 at Wrexham Maelor Hospital, Croesnewydd Road, Wrexham, UK. N Makwana MBBS FRCS (Tr & Orth) is a Consultant Foot & Ankle Orthopaedic Surgeon at Wrexham Maelor Hospital, Croesnewydd Road, Wrexham, UK and Robert Jones & Agnes Hunt Hospital, Oswestry, UK.
ORTHOPAEDICS AND TRAUMA 23:4
Box 1
274
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
have noticed that their feet (cavus, occasionally planus) or toes (clawing) have changed shape. This is almost always bilateral. They, too, may complain of ‘‘pins and needles’’ and sometimes pain, in upper and lower extremities as well as clumsiness and weakness of the hands. In children, parents may say children are clumsy or inactive. Though generally considered painless, neuropathic pain is seen in CMT. This appears to be under-reported.2 A detailed family history in these patients is important. On discovering these progressive feet abnormalities it is always worth considering the differential diagnoses, particularly in cavus feet (Table 1).
of the hindfoot (Figure 2) which should be considered before deciding upon treatment. By standing the patient on a block at the angle shown, the 1st ray can be offloaded and the hindfoot can then be assessed for full or partial correction of its apparent varus.7 Occasionally the lesser metatarsals may also be depressed, which means a slight modification of the Coleman block test (i.e. angle the foot so the lesser metatarsal heads are also offloaded).
Diagnosis Once the above history and findings have suggested a diagnosis of CMT, a number of further tests can be used to confirm it. These consist of electrophysiological and genetic assessmen, and occasionally nerve biopsy.
Clinical examination The classical appearances of ‘‘inverted champagne bottle’’ legs with pes cavus and hammer toes (Table 2) are not always present, but should be sought. Specific distal lower limb muscle wasting should be assessed and MRC graded power in these groups should be documented. Deep tendon reflexes are commonly diminished or absent. Patients may have sensory ataxia, resulting in a positive Rhomberg’s test. It is not uncommon to be able to palpate thickened posterior auricular nerves, and some patients may also develop sensorineural deafness. Patients usually don’t perceive sensory deficit, but formal testing can elicit diminished proprioception and vibration sense, and later problems with pain and temperature may be encountered. Other orthopaedic manifestations of CMT include hip dysplasia3 and scoliosis, the incidence of which is approximately 25%, but this depends on the CMT type, with CMT-1 appearing to predispose most strongly to spinal deformity.4
Electrophysiology Nerve conduction velocities and amplitudes are tested for reductions of either or both. Electromyography is also performed to assess which muscle groups are affected, and to what extent. CMT1 usually exhibits reduced velocities (abnormal myelin) and normal amplitudes. CMT2 demonstrates normal velocities but reduced ampli tudes (dysfunctional axons). Other forms can manifest with a variety of combinations of the above. Genetic testing Only some forms of CMT1 can be recognised by this means. May be useful for patients concerned about transmission to offspring.
Pathophysiology The pattern of weakness in the distal leg muscles in CMT is characteristic. There is a critical distribution of muscles affected which results in the classical deformity. The anterior compartment is principally affected, while in the lateral compartment the peroneus brevis is more severely affected than the longus.5,6 The intrinsics are weak; these are usually the first muscles affected in the hand too. Clawing of the lesser toes is due to weakness of the intrinsic muscles and relative sparing of the extrinsics. The cavus foot, in part, is produced by extension contractures of the metatarso-phalangeal joints, causing tightening of the plantar fascia, but more importantly by the relatively intact peroneus longus muscle plantarflexing the first ray by overpowering the weakened tibialis anterior. This in turn contributes to the varus of the hindfoot, further exaggerated by the action of tibialis posterior, which is relatively unopposed because of the more weakened peroneus brevis muscle. Figure 1 illustrates a classical pattern of deformity seen in CMT. The hindfoot varus is usually correctable, often until late in the disease. The ‘‘Coleman block test’’ is useful in assessing this flexibility
Nerve biopsy Outdated practice Rarely used
Potential causes of Cavus Foot Neuromuscular C Peripheral neuropathy e CMT C Spinal cord disease e poliomyelitis, neoplasia, syringomyelia. C CNS disease e Freidrich’s ataxia, cerebral palsy C Myopathy e muscular dystrophy Congenital C Arthrogryposis C Residual clubfoot deformity Trauma C Post compartment syndrome Idiopathic Figure 1 Classical appearance in the lower legs in a patient with Charcot Marie Tooth Disease.
Table 1
ORTHOPAEDICS AND TRAUMA 23:4
275
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
Operative The surgical treatment of CMT foot deformity tends to follow a stepwise approach that may include:
soft tissue procedures osteotomies arthrodeses. The principle of treatment is to align the foot under the tibia and the sole flat to the ground. The muscles around the foot are then balanced. Orthoses may still be needed. In general, soft tissue procedures are reserved for children, osteotomies and soft tissue procedures are beneficial in adults, and fusions should be reserved for the older patient with degenerative changes and/or deformity. There is no agreement on the timing of surgical intervention, but generally the soft-tissue procedures and osteotomies are best performed in mobile joints, and the arthrodesis reserved for more severe fixed deformities.
Figure 2 Correction of hindfoot varus with Coleman Block Test.
C C C C C C
C
Soft tissue procedures The philosophy of these procedures is to use the relatively spared muscles to bolster those that are most severely affected. The weak peroneus brevis predisposes to ankle instability and the relatively preserved peroneus longus muscle tends to promote the cavus deformity. By transferring the longus to the brevis both problems may be lessened. The Jones procedure may be useful. EHL is detached from the hallux and transferred to the neck of the first metatarsal, often with a synchronous fusion of the interphalangeal joint. This allows the EHL to dorsiflex the ankle, without worsening of the claw deformity. It sometimes needs to be supplemented with a closing wedge osteotomy of the first metatarsal to allow full correction. There is little evidence to show that these procedures delay the onset of more severe deformity. Plantar fascial release proximally is no longer recommended.
Often genetic transmission Affects motor and sensory nerves Upper and lower limbs affected History of unsteadiness/clumsiness and ankle sprain Classical pattern of nerves involved Lower limbs more severely affected B inverted champagne bottle legs B cavus feet with hammer toes Clumsiness and intrinsics wasting most common findings in upper limbs
Osteotomies These are usually used when the majority of the deformities are correctable but one or two are not. For example, a dorsiflexion closing wedge osteotomy at the base of the first metatarsal may be used if fixed plantarflexion at the first ray has occurred. Alternatively various calcaneal osteotomies may be use to correct heel position in fixed situations, or allow lateralisation of the tendo achilles (TA).
Table 2
Management
Arthrodeses Triple arthrodesis is the most widely used skeletal procedure for the fixed cavovarus foot. Evidence suggests that the operation produces good long-term results10 although others have reported that over three quarters of CMT patients experience only fair to poor results at 20 years.11 It is thought that the main reason for this is recurrence of deformity and the development of ankle degenerate change. Many patients go on to require pantalar athrodesis. Due to the risk of recurrent deformity, particularly with fusions in the young patient, most advocate the use of soft tissue balancing procedures in combination with fusion (Table 3).
As already discussed, CMT is a progressive disease and as yet there is no known cure. Management of these patients is aimed at keeping them mobile and independent for as long as possible. It is influenced by symptoms and the extent to which the patient complains, whether from footwear problems, ankle instability, pain, ulcers or stress fractures.
Non-operative Lifestyle factors, such as reducing weight and keeping fit, can help ensure patient mobility. Patients should also avoid drugs that can potentiate neuropathy, such as nitrofurantoin, isoniazid and also alcohol to excess. The mainstay of non-operative treatment involves a combination of keeping the joints supple with regular stretches and a resort to static and dynamic bracing. Though useful in controlling symptoms. Evidence is unconvincing regarding improvement,8 and most reports suggest it makes no difference.9 In the early stages regular stretching of the calf is useful, and simple ankle supports may reduce the incidence of ankle sprains. Once more severe foot- drop occurs lightweight ankle-foot-orthoses (AFOs) with assisted dorsiflexion can be used. Later. when the deformities are more pronounced, patients often need specifically moulded AFOs. Devices are available that appear to maintain movement and muscle bulk by electric stimulation. These threshold electrical stimulation machines are not widely used and there is to date no evidence supporting their use.
ORTHOPAEDICS AND TRAUMA 23:4
Treatment of CMT Non-operative C weight loss C avoidance of certain drugs C accommodative footwear C simple bracing C AFO Operative C soft tissues/tendon transfers C osteotomies (midfoot and hindfoot) C arthrodeses Table 3
276
Ó 2009 Elsevier Ltd. All rights reserved.
ADULT PATHOLOGY
Summary Charcot-Marie-Tooth disease remains a very challenging condition to treat. As no cure exists at present the mainstay of treatment is to maintain mobility and independence. Though affecting both upper and lower limbs, it is the legs that are usually more severely affected and often require orthotic or surgical treatment. Other manifestations, such as hip dysplasia and scoliosis, may require surgery if symptomatic or progressive. Surgical treatment remains a challenge as there is very little strong evidence to support the different options, and complications and recurrence of deformity are relatively common. It is clear that genetic or medical management remains the only hope for a true cure. Bracing and surgery only provide symptomatic relief and a slight improvement in gait. Genetic counselling should be offered for all patients affected with CMT, thus giving a clear idea of the risks of inheritance. A
5 6
7 8
9
10 REFERENCES 1 Berciano J, Garcia A, Calleja J, Combarros O. Clinicoelectrophysiological correlation of extensor digitorum brevis muscle atrophy in children with Charcot Marie Tooth disease 1A duplication. Neuromuscul Disord 2000; 10: 419e24. 2 Carter GT, Jenson MP, Galer BS, et al. Neuropathic pain in CharcotMarie-Tooth disease. Arch Phys Med Rehabil 1998; 79(12): 1560e4. 3 Walker JL, Nelson KR, Heavilon JA. Hip abnormalities in childrenwith Charcot-Marie-Tooth diease. J Pediatr Orthop 1994; 14: 54e9. 4 Horacek O, Mazanec R, Morris CE, Kobeova A. Spinal deformities in hereditary motor and sensory neuropathy: a retrospective
ORTHOPAEDICS AND TRAUMA 23:4
11
qualitative, quantitative, genotypical, and familial analysis of 175 patients. Spine 2007; 32(22): 2502e8. Mann RA, Missirian J. Pathophysiology of Charcot-Marie-Tooth disease. Clin Orthop 1998; 234: 221e8. Tynan MC, Klenerman L, Helliwell TR, Edwards RH, Hayward M. Investigation of muscle imbalence in the leg in symptomatic forefoot pes cavus: a multidisciplinary study. Foot Ankle 1992; 13: 489e501. Coleman SS, Chestnut WJ. A simple test for hindfoot flexibility in the cavovarus foot. Clin Ortop Relat Res 1977; 123: 60e2. Guzian MC, Bensoussan L, Viton JM. Orthopaedic shoes improve gait in Charcot-Marie-Tooth patient: a combined clinical and quantified case study. Prosthet Orthot Int 2006; 30(1): 87e96. Refshauge KM, Raymond J, Nicholson G. Night splinting does not increase ankle range of motion in people with Charcot-Marie-Tooth disease: a randomised, cross-over trial. Aust J Physiother 2006; 52(3): 193e9. Saltzman CL, Fehrle MJ, Cooper RR. Triple arthrodesis: twenty-five and forty-four year average follow-up of the same patients. J Bone Joint Surg Am 1999; 81(10): 1391e402. Wetmore RS, Drennan JC. Long-term results of triple arthrodesis in Charcot-Marie-Tooth disease. J Bone Joint Surg Am 1989; 71: 417e22.
Acknowledgement With thanks to Mr. P Cooke MB,ChB,FRCS,ChM, Consultant Orthopaedic Surgeon, Nuffield Orthopaedic NHS Centre, Oxford.
277
Ó 2009 Elsevier Ltd. All rights reserved.