segunda-feira, 4 de maio de 2015

Footdrop, foot rotation, and plantarflexor failure in Charcot-Marie-Tooth disease☆☆☆

Presented in part at the 8th Annual Symposium of the European Charcot-Marie-Tooth Consortium, July 2-4, 1999, Antwerp, Belgium.
Paolo Vinci, MD
,
 Sandra L. Perelli, MD
Department of Rehabilitation of Charcot-Marie-Tooth Disease and Other Neuromuscular Disorders, Specialized Rehabilitation Hospital L. Spolverini, Ariccia (Vinci); Italian Charcot-Marie-Tooth Association, Rome (Vinci, Perelli); and School for Physiotherapists, University La Sapienza, Rome (Vinci, Perelli), Italy
Received in revised form: May 10, 2001; Accepted: May 10, 2001;

Abstract

Vinci P, Perelli SL. Footdrop, foot rotation, and plantarflexor failure in Charcot-Marie-Tooth disease. Arch Phys Med Rehabil 2002;83:513-6. Objective: To evaluate the frequency of occurrence of the main causes of poor stance and gait in patients with Charcot-Marie-Tooth disease (footdrop graded as mild or severe, rotation, and plantarflexor failure) both as single and associated problems. Design: Observational. Setting: A neuromuscular disorders department in a specialized Italian rehabilitation hospital. Participants: One hundred twenty-six nonoperated lower limbs from 64 outpatients. Interventions: Ankle angle during active dorsiflexion and heel angle in stance were measured in a photograph; the ability to raise the heel at least 2cm was evaluated. Main Outcome Measures: Frequency of mild footdrop (ankle angle ≤100°), severe footdrop (ankle angle >100°), and rotation and plantarflexor failure singularly and in association. Results: Mild footdrop was present in 47.6% of examined limbs and was associated with rotation in 39.7% of limbs; severe footdrop was present in 52.4% of limbs and was associated with rotation in 28.6% of limbs, with rotation plus plantarflexor failure in 21.4% of limbs. Conclusions: We recommend categorizing problems in the lower limbs into 4 levels of increasing symptom severity, starting with mild footdrop and graduating to the instance where the 3 problems are associated. © 2002 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Keywords:

Charcot-Marie-Tooth disease, Hereditary motor and sensory neuropathies, Physiotherapy, Rehabilitation
CHARCOT-MARIE-TOOTH DISEASE (CMT) is a genetically heterogeneous disorder characterized by degeneration of the longest motor and sensory nerve fibers, with consequent distal muscle weakness and sensory reduction.1 With a prevalence of 1 case in 2500, CMT is among the most common hereditary disorders2 and a genetic ailment of considerable importance to rehabilitation professionals.3
CMT can be caused by a myelin defect (demyelinating forms) or by a primary axonopathy (axonal forms): the 2 forms can be distinguished on the basis of the motor nerve conduction velocity in the median nerve being lower or higher than 38m/s.4 Types 1 and 2 (CMT1, CMT2) are the demyelinating and axonal forms on a dominant transmission; type 3 (CMT3) is the early-onset severe demyelinating form (Dejerine-Sottas disease), and type 4 (CMT4) includes the autosomal recessive demyelinating and axonal forms.5
Four genes5 have already been discovered as responsible for most cases of CMT1. CMT1A, caused by duplication of the gene coding for the peripheral myelin protein 22 gene, accounts for two thirds of CMT1 cases.6 Other forms of CMT1 occur because of mutations in the peripheral myelin protein 22, PO, CX32, and EGR2 genes. So far, only 1 CMT2 and 2 CMT4 genes have been discovered.
Weakness and wasting generally start from the intrinsic foot muscles and spread to the leg muscles, causing symptoms and signs related both to the muscle weakening and to the consequent biomechanic problems including ankle sprains, stumbling, shuffles, clumsy gait, pain, poor balance, steppage gait, foot deformities (pes cavus, equinovarus, calcaneovarus, pes planus, hammertoe, clawtoe) and knee deformities (genu recurvatum). Only a few cases present severe weakening of the thigh and the pelvic girdle muscles with loss or severe reduction of ambulating.7 Impairment of sensation is generally mild and is rarely responsible itself for severe disability.
In the upper limbs, a weakening in the intrinsic muscles of the hands starts later and is mild in most patients. Finger deformities are generally absent or mild, and functional impairment related to atrophic intrinsic hand muscles is never very severe.8 However, many patients have difficulties in performing daily activities requiring dexterity.9
Typical of the disease is the degree to which cases vary in clinical severity among different families and within the same family.10 Clinical variability has been found even in identical twins when 1 twin is more severely affected than the other.11
The average age of clinical onset of CMT is 12.2 ± 7.3 years,12 but there are cases with onset as late as in the seventh decade and cases starting in infancy, as happens in CMT3.10
Because a drug or a gene therapy to heal this disease is still unavailable, the only treatment to improve patients' functional abilities and quality of life is rehabilitation.9 Rehabilitation consists of all the therapeutic interventions, conservative and surgical, made by many professionals (physiatrist, physiotherapist, pedorthist, orthotist, occupational therapist, orthopedist, geneticist, psychologist) aimed at reducing the disability that arises from the problems caused by or related to CMT.
A recently proposed13, 14 list of rehabilitation management goals includes the following program objectives: improvement of muscle strength, prevention of joint deformities, promotion of mobility, prevention of falls, improvement of hand function, resolution of psychologic problems, and prevention and treatment of pain. The role of exercise to strengthen the muscles weakened by CMT is not yet well defined.14, 15, 16, 17, 18 Adaptive equipment is successful in retaining the ability to perform daily activities and in avoiding easy tiring of hands muscles.16, 17 Therefore, most rehabilitation management is aimed at improving stance and gait, through prevention and treatment of deformities, pain, footdrop, and other factors that cause functional impairment.14 A review of the literature has shown that few works focused on easy evaluation and treatment of stance and gait problems.14, 15, 16
Our daily practice with patients affected with CMT teaches us that the main problems we face in mild and moderate cases are foot rotation, footdrop, and plantarflexor failure. Mildly and moderately affected patients represent the majority of CMT cases. Severe cases (those with weakening in the muscles above knees) generally represent less than 15% of all cases. The major problems for stance and gait, presented by severely affected patients, are related to the destabilization of knee and, occasionally, hip joints.14 Foot rotation on its longitudinal axis is the result of an imbalance between pronator (everter) and supinator (inverter) strengths and generally is in inversion because the everter muscles are either weakened more than their antagonists or unable to produce strength as the consequence of biomechanical problems.19 In stance, rotation in inversion reduces the area in which the foot contacts the floor, with consequent reduction of balance and pain under the lateral border where pressure is concentrated. As rotation and instability increase, ankle sprains may occur in the weight-bearing phase, causing a stretching of the lateral ligaments of the ankle. In stance, patients react to the foot rotation in supination by hip internal rotation and flexion and knee bending, exibiting a clumsy posture that produces hip rigidity and pelvis antiversion with low back pain.20
Lateral wedges placed under the foot orthoses or directly under the shoes prevent or reduce the foot rotation in stance. They also functionally stretch the muscles that cause inversion in swing. Surgical interventions for foot rotation are intended to rebalance the muscle strengths or to fix joints in which rotation happens.
Footdrop is caused by a malfunctioning or a reduction of strength of the foot dorsiflexor muscles. In the early stages of the disease, the forefoot dorsiflexors (extensor hallucis longus and extensor digitorum longus muscles) are still strong but cannot work properly (malfunctioning) because the metatarsophalangeal joints are not stabilized by the flexor hallucis brevis and the lumbricales, which are weakened by the disease. Consequently the forefoot is plantarflexed rather than dorsiflexed.14 At a later stage, footdrop is caused by the weakening of the leg muscles, especially of the peroneal ones, which are selectively involved by the neuropathy. Footdrop alters the swing phase of gait because the foot is unable to dorsiflex up to 90°, making the limb functionally longer. Footdrop is an important cause of impairment of barefoot gait, but its functional relevance for ambulation as a daily activity is diminished by the fact that all shoes have some heel. Walking with heeled shoes does not require the ankle to be dorsiflexed at 90° during swing, as it does when barefoot, because the square angle is calculated between the axis of the leg and the tangent to the lowest points of the heel and sole of the shoe rather than to the sole of the foot.9, 10, 11, 12, 13, 14 We can classify footdrop as either mild or severe on the basis of the ankle angle being up to or greater than 100°. A footdrop up to 100° allows all our patients to walk without evident steppage if their ready-made shoes have a bit of heel. This limit is the highest value of the ankle angle we have measured on our patients who show a weakening limited to the foot muscles and show only a pure forefoot drop. Patients with an ankle angle greater than 100° cannot generally compensate for their footdrop by wearing heeled shoes, and therefore ankle-foot orthoses21 or dropfoot boots13, 14, 15, 16, 17, 18, 19, 20, 21, 22 are necessary.
Plantarflexor failure is the third important problem a rehabilitation professional must consider. It can happen even if the plantarflexor muscles are not severely involved by the neuropathy if a concomitant foot rotation reduces their performance because of biomechanic alterations. A plantarflexor failure is present when patients are unable to stabilize the ankle joint in the sagittal plane while wearing a shoe with a 2-cm heel, which is the most common heel height for ready-made footwear. It is very important to remember that a bit of heel is the easiest compensation for mild footdrop and avoids the need of a dorsiflexion assisting device, which is generally poorly accepted by people with CMT. Unless there is an equinus deformity, patients with weak plantarflexors do not tolerate heeled shoes because the triceps surae muscle is not able to stabilize the ankle joint in plantarflexion. If they do wear them, they have to keep their knees slightly bent.23Therefore, the quadriceps muscles tire easily or cramps may occur.9, 10, 11, 12, 13, 14 Additionally, knees can suddenly bend too much and the patient occasionally falls.
Because of the importance of these factors for stance and gait, and therefore for rehabilitation, we undertook a study to evaluate the frequency of each of them and their association in the nonoperated lower limbs of mildly and moderately affected CMT types 1 and 2 patients who were referred to our rehabilitation hospital from October 1999 to July 2000. The aim was to help rehabilitation professionals easily assess and classify the impairment in the lower limbs presented by patients affected with CMT and to address their rehabilitation.

Methods

Participants

One hundred ninety-six lower limbs from 98 patients were examined. One foot of a patient with CMT2B had been amputated. Some patients had undergone surgery on 1 or both lower limbs with different methods and results. Twelve patients (24 limbs, 12.2%) had complete muscle atrophy below the knee and severe weakening of the proximal muscles, which caused significant reduction or loss of ambulation: 21 feet of these patients had had surgery on 1 or more occasions.
Because we focused on evaluating functional impairment caused by the natural evolution of the disease, we excluded operated feet. We also excluded limbs with severe weakness of the thigh and pelvic girdle muscles because their major problems were different from those described in this study.
At the end of this selection, 126 feet from 64 patients were examined by the same method to evaluate footdrop (graded as mild or severe), foot rotation, and functionality of plantarflexors. Ninety-nine feet belonged to patients affected with CMT1 (63 with type 1A) and 27 to the patients with type 2.

Design

Evaluation of footdrop and subdivision in mild and severe footdrop

Patients were asked to stand on 1 leg and to dorsiflex the foot of the other, keeping the knee slightly bent (5°) and the whole limb forward. A photograph was taken in this position, with the camera at the level of the ankle and the photographer at the side opposite the foot to be photographed. Patients were told to keep the foot straight so that the medial side of the foot was on a plane frontal to the camera. The angle between the axis of the leg and the sole of the foot (ankle angle) was measured on the photograph. Patients with an angle greater than 90° and up to 100° were considered to be affected with mild footdrop. If the angle was greater than 100°, the footdrop was considered severe.

Evaluation of foot rotation

Rotation of the foot on the longitudinal axis can lead to inversion or, less frequently, to eversion. Seen from the back, the angle between the axis of the leg and the axis of the heel (heel angle), which is normally 5° open outside, reduces to 0° and becomes negative in case of inversion and increases in case of eversion. The heel angle was measured on a photograph taken from behind the patient while he/she stood barefoot. The camera was positioned just above the floor and 1m away from the patient. Additionally, a footprint was taken to see if the foot width was reduced (inversion with pes cavus) or increased (eversion with flat foot). Feet with mild deviation from normal (heel angle reduced to 0° or increased up to 10°, footprint width reduced or increased up to 10% of the normal value) were considered to be normal.

Evaluation of plantarflexors

Our assessment was not aimed at measuring only the strength of plantarflexors, as in normal individuals: we knew that concomitant foot rotation would have reduced their performance because of biomechanic alterations. The purpose of our testing was to determine if the patient was able to stabilize the ankle joint while wearing shoes with 2cm of heel, with the stability attributable to active contraction of the triceps surae muscle. Patients were asked to raise the heel from the floor while trying to go up on their tiptoes24 with knee and body straight and with lateral wedges correcting rotation. Patients who were unable to raise their heels for at least 2cm were considered to have a plantarflexor failure.

Considerations

Each leg could have 1 or more problems. The number of legs with each single problem and its frequency were calculated. Legs with the same association of problems were counted to determine the frequency of each association. In theory, 10 groups could be defined: single mild footdrop, single rotation, single severe footdrop, single plantarflexor failure, mild footdrop and rotation, mild footdrop and plantarflexor failure, severe footdrop and rotation, severe footdrop and plantarflexor failure, mild footdrop plus rotation and plantarflexor failure, and severe footdrop plus rotation plus plantarflexor failure.

Results

The results are reported in tables 1 and 2.
Table 1: Single problems
Single ProblemsNo. Cases (n)%
Mild footdrop6047.6
Severe footdrop6652.4
Rotation (inversion + eversion)113 (100 + 13)89.7
Plantarflexor failure2721.4
Table 2: Associations of problems
Associations of ProblemsNo. Cases (%)
Nonassociated mild footdrop (forefoot drop)10 (7.9)
Nonassociated severe footdrop3 (2.4)
Nonassociated rotation0
Nonassociated plantarflexor failure0
Mild footdrop and rotation50 (39.7)
Severe footdrop and rotation36 (28.6)
Mild footdrop and plantarflexor failure0
Severe footdrop and plantarflexor failure0
Mild footdrop, plantarflexor failure, and rotation0
Severe footdrop, plantarflexor failure, and rotation27 (21.4)

Discussion

In the present study, we examined 126 nonoperated lower limbs from 64 patients affected with CMT types 1 and 2 to evaluate the presence of footdrop (graded as mild or severe), rotation, and plantarflexor failure. These are the most important problems in the subjects who have no severe weakness of the proximal muscles. Analysis of single alterations revealed that rotation and footdrop, either mild or severe, were the most frequent and constant problems, whereas a plantarflexor failure was found only in 21.4% of the examined limbs. All the patients had footdrop, either mild or severe.
Mild footdrop alone was found only in 10 feet (5 patients). Two considerations might account for the low number of subjects in that group. First, gait impairment caused by mere mild forefoot drop seldom requires rehabilitative intervention because almost all individuals wear shoes with a small heel, which improves or normalizes ambulation. Second, patients prefer not to consider themselves affected by the disease, at least when disability is mild, and therefore do not require rehabilitative consultation.9, 10, 11, 12, 13, 14, 15, 16, 17, 18
Absence of rotation in 10 limbs with pure forefoot drop might be explained by mild muscle involvement still restricted to the intrinsic foot muscles, as happens in the beginning of the disease. Absence of rotation in 3 patients with severe footdrop might be attributed to our definining as normal all feet with mild deviation from normal. Because plantarflexor failure was always associated with rotation and severe footdrop, it is, therefore, part of the most severe association of problems.
We did not perform a correlation between associations of problems and disease duration because (1) the clinical phenotype was intrinsically variable and (2) the sample was heterogeneous.

Conclusions

Our results suggest that CMT patients with nonoperated lower limbs and no severe weakness of the proximal muscles can be categorized into 4 levels25 according to increasingly severe symptoms, as follows: level 1, forefoot drop or mild footdrop; level 2, mild footdrop plus rotation; level 3, severe footdrop with or, less frequently, without significant rotation; and level 4, severe footdrop plus plantarflexor failure plus rotation.
Although a follow-up study is necessary to show the correlation between these levels and disease duration, we believe that this grading system can help rehabilitation professionals to evaluate easily the severity of rehabilitative problems and provide the most appropriate rehabilitation.

References

  1. Dyck, PJ, Chance, PF, Lebo, RV, and Carney, JA. Hereditary motor and sensory neuropathies. in: Peripheral neuropathy. 3rd ed. WB Saunders, Philadelphia; 1993: 1094–1136
  2. Martyn, CN and Hughes, RA. Epidemiology of peripheral neuropathy. J Neurol Neurosurg Psychiatry. 1997; 62:310–318
  3. Bazzini, G and Franchignoni, F. Percorsi riabilitativi nelle malattie neuromotorie.. in: N Ambrosino, G Bazzini, F Cobelli, (Eds.) Percorsi valutativi e terapeutici in medicina riabilitativa. Linee guida operative. Fondazione Salvatore Maugeri, Pavia (Italy); 1997: 149–208
  4. Harding, AE and Thomas, PK. The clinical features of hereditary motor and sensory neuropathy, types I and II.Brain. 1980; 103: 258–280
  5. Nelis, E, Haites, N, and Van Broeckhoven, C. Mutations in the peripheral myelin genes and associated genes in inherited peripheral neuropathies. Hum Mutat. 1999; 13: 11–28
  6. Dupré, N, Bouchard, JP, Cossette, L et al. Clinical and electrophysiological study in French-Canadian population with Charcot-Marie-Tooth disease type 1A associated with 17p11.2 duplication. Can J Neurol Sci. 1999; 26: 196–200
  7. Vinci, P, Manzetti, S, and Manupelli, F. Atrofia muscolare peroneale: osservazioni su tre casi. Stampa Med Eur.1983; 3: 89–92
  8. Njegovan, ME, Leonard, EI, and Joseph, FB. Rehabilitation medicine approach to Charcot-Marie-Tooth disease.Clin Podiatr Med Surg. 1997; 1: 99–116
  9. Vinci, P and Perelli, SL. Malattia di Charcot-Marie-Tooth: aspetti clinico-riabilitativi. Neurol News. 1999; 2: 3–31
  10. Garcia, CA. The clinical features of Charcot-Marie-Tooth disorders. in: Charcot-Marie-Tooth disorders: a handbook for primary care physicians. Charcot-Marie-Tooth Assoc, Upland (PA); 1995: 5–17
  11. Garcia, CA, Malamut, R, Parry, GJ et al. Clinical heterogeneity of HMSN1 in two pairs of identical twins.Neurology. 1990; 40: 301
  12. Shy, ME, Kamholz, J, and Lovelace, RE. Introduction to the Third International Symposium on Charcot-Marie-Tooth Disorders. in: Charcot-Marie-Tooth disorders. N Y Acad Sci, New York; 1999: xiii–xviii
  13. Martini, R, Berciano, J, and Van Broeckhoven, C. 5th Workshop of the European CMT Consortium, 69th ENMC International Workshop: therapeutic approaches in CMT neuropathies and related disorders 23-25 April 1999, Soestduinen (The Netherlands). Neuromuscul Disord. 2000; 10: 69–74
  14. Vinci, P and Perelli, SL. Trattamento riabilitativo della malattia di Charcot-Marie-Tooth (CMT). Ital J Med Rehabil. 2000; 3: 203–208
  15. Vinci, P. Strengthening of the proximal muscles in Charcot-Marie-Tooth disease [letter]. Arch Phys Med Rehabil. 2001; 82: 563
  16. Oatis, CA, Sundberg, D, Oliver, C, and Yerkes, P. Conservative management in patients with Charcot-Marie-Tooth disorders. in: Charcot-Marie-Tooth disorders: a handbook for primary care physicians. Charcot-Marie-Tooth Assoc, Upland (PA); 1995: 103–116
  17. Vinci P, Perelli SL, Colazza GB. Overwork weakness in Charcot-Marie-Tooth disease. In: Abstract Book of the 9th Annual Symposium of the European Charcot-Marie-Tooth Consortium; 2001 June 30-July 1; Antwerp (Belg). p 34.
  18. Oatis, CA. Conservative management of the functional manifestations of Charcot-Marie-Tooth disease. in:Charcot-Marie-Tooth disorders: pathophysiology, molecular genetics and therapy. Wiley-Liss, New York; 1990: 416–427
  19. Kapandj, IA. The physiology of the joints: annotated diagrams of the mechanics of the human joints: lower limbs. Churchill Livingstone, Edinburgh; 1988
  20. Geurts, AC, Mulder, TW, Nienhuis, B, Mars, P, and Rijken, RA. Postural organization in patients with hereditary motor and sensory neuropathy. Arch Phys Med Rehabil. 1992; 73: 569–572
  21. Siegel, I. Management of musculoskeletal complications in neuromuscular disease: enhancing mobility and the role of bracing and surgery. Phys Med Rehabil State Art Rev. 1988; 2: 553–575
  22. Vinci, P and Perelli, SL. Efficacy of our totally inshoe device to correct footdrop in Charcot-Marie-Tooth disorders and other neurological diseases [abstract]. Ital J Neurol Sci. 1999; 4: S149
  23. Marchetti, M and Pillastrini, P. Neurofisiologia del movimento. Piccin Nuova Libraria, Padova (Italy); 1997
  24. Hislop, H. Daniels and Worthingham's muscle testing: techniques of manual examination. 6th ed. WB Saunders, Philadelphia; 1995
  25. Timmermann, V, De Jonghe, P, and Van Broeckhoven, C. Report of the 8th Annual Symposium of the European Charcot-Marie-Tooth Consortium, Antwerpen, Belgium, July 2-4, 1999. J Peripheral Nerv Syst. 1999; 4: 279–304
Postado por às

Nenhum comentário:

Postar um comentário

Assinar: Postar comentários (Atom)