Overview
Peroneal muscular dystrophy is a hereditary peripheral neuropathy.
It is characterized by symmetrical, slowly progressive distal muscle atrophy, weakness and hyperalgesia.
Caused by various genetic mutations
There is no cure; treatment requires a combination of rehabilitation, orthotics, orthopedic surgery, and medication.
Definition
Peroneal muscular dystrophy is not a specific disease, but a group of hereditary peripheral neuropathies.
Clinical manifestations include symmetric, slowly increasing muscle atrophy, weakness and sensory loss in the hands and feet (distal extremities), with gradual progression to the upper arms and thighs (proximal extremities) [1].
Most patients develop in adolescence, with less motor ability than their peers, difficulty in running, easy twisting of the foot, foot drop, and atrophy of the calf peroneus brevis muscle (lateral calf muscle).
Classification
According to the neurophysiological and pathological features, peroneal muscular atrophy can be classified into demyelinating type, axonal degeneration type, and intermediate type in which demyelination and axonal degeneration coexist [2].
According to genetic loci and causative genes, it can be divided into different genetic subtypes, and more than 80 causative genes have been cloned [2].
Morbidity
The prevalence of the disease is about (40-80)/100,000 [3].
There is no significant difference in incidence between races.
Questions you may be concerned about
What is peroneal muscular dystrophy?
Peroneal muscular atrophy is a familial hereditary peripheral neuropathy characterized by slowly progressive atrophy, weakness, and sensory loss of the distal muscles of the lower extremities.
Peroneal muscular atrophy, also known as Charcot-Marie-Tooth disease (CMT) and hereditary motor-sensory peripheral neuropathy, is a familial hereditary peripheral neuropathy with the same clinical phenotype. It is mainly autosomal dominant and occurs in children and adolescents, with a prevalence of about 40/100,000.
The main clinical manifestations of the disease are muscle atrophy, weakness and sensory loss in the distal lower limbs. Muscle atrophy is usually chronic, progressive and symmetrical, usually starting from the foot and calf, during which muscle weakness, sensory impairment or deficit occurs.
As the disease progresses, it can gradually progress to the thighs and upper limbs. When all the muscles of the calf and the lower 1/3 of the thigh are atrophied, a \”crane leg\”-like change can occur; when the hand and forearm muscles are atrophied, movement disorders such as fastening buttons and unlocking locks can occur.
When this disease occurs, it is necessary to actively consult the doctor, under the guidance of the physician reasonable treatment.
Causes
Causes
Peroneal muscular atrophy is a group of peripheral neuropathies caused by mutations in different genes.
Commonly mutated genes include PMP22, MPZ, GJB1, MFN2, NEFL, and GDAP1 [4].
Predisposing factors
The disease is hereditary with no clear predisposing factors.
High risk factors
The disease tends to develop in adolescents with a family history of the disease.
Pathogenesis
This disease is caused by a genetic mutation that results in a disorder of neuraxonal formation, which affects the normal function of peripheral nerves.
Gene mutations affect the formation of myelin sheath of peripheral nerves, resulting in impaired cell membrane transport function and cell metabolism [5], and sensory and motor signals transmitted through the peripheral nerves are unable to be transmitted downward, resulting in manifestations such as muscular atrophy and sensory deficits.
The common mutant gene types are the five subtypes of PMP22 duplication, GJB1 mutation, (leading to additional disease) MPZ mutation, and MFN2 mutation [6].
Symptoms
Main symptoms
The disease usually develops in childhood or adolescence, and in a few cases may start in middle age, and is characterized by chronic progressive, symmetric muscle weakness and atrophy of the distal limbs and sensory deficits.
Muscle atrophy and weakness usually start from the foot and calf, with foot drop and walking in a cross-threshold gait, i.e., before the toe of one side leaves the ground, the leg of that side has to be elevated before the foot can be dragged across the step, which is like crossing a threshold.
The patient has difficulty running and walking, and is prone to falls and sprains.
Muscle atrophy of the foot can lead to an increase in the arch of the foot, resulting in an arched foot.
Atrophy of the calf muscles gives the entire lower limb an inverted champagne bottle shape, known as \”crane leg\”.
When muscle weakness and atrophy spreads to the hands and forearms, the patient may have difficulty fastening buttons and opening locks.
Consultation
Department of Medicine
Neurology
Neurology is the first place to go if you have the above symptoms.
Orthopedics
If the diagnosis of peroneal muscular dystrophy is clear and surgical orthopedic treatment is required, consult the Department of Orthopedics.
Rehabilitation
If the diagnosis of peroneal muscular dystrophy is clear and long-term systematic rehabilitation treatment is required, the Department of Rehabilitation can be consulted.
Preparation
Consultation: Registration, Preparation of documents, Frequently Asked Questions
Tips for medical treatment
Be accompanied by your family members to avoid falling on the way to the hospital or inaccurate description of your medical history.
Preparation Checklist
Symptom list
Pay particular attention to the time of onset of symptoms, special manifestations, etc.
Is there any slowly progressive bilateral lower limb muscle atrophy, muscle weakness?
Is there any muscle atrophy in the lower limbs that causes a \”crane leg\” appearance?
Are there bowed feet?
Is there any slowly progressive bilateral hypesthesia or loss of sensation in the lower limbs?
Do you need to lift your legs high to get your toes off the ground when walking, like crossing a threshold?
Are you particularly prone to falling or spraining your ankles when running or walking?
Do you have difficulty completing actions such as fastening buttons or unlocking locks?
Medical History Checklist
Is there a family history of peroneal muscular dystrophy?
Any past history of cranial trauma, intracranial infections, etc.?
Any recent history of diarrhea, respiratory infections?
Checklist
Test results from the last six months to bring to the doctor\’s office
Electromyography.
Other tests: blood test, liver and kidney function, etc.
Medication list
Medication in the last 3 months, if available in boxes or packages, bring along for medical consultation
Symptomatic treatment and nutritive nerve drugs: baclofen, methylcobalamin, vitamin B6, etc.
Other medications being taken orally in the recent past.
Diagnosis
Diagnosis based on
Medical history
Past history of difficulty walking or running, frequent falls, and sprained feet.
Family history of patients who may have similar clinical presentations or who have been diagnosed with peroneal muscular dystrophy.
Clinical manifestations
Symptoms
It often develops in childhood or adolescence and is characterized by chronic progressive, symmetrical weakness and atrophy of the distal limb muscles and sensory deficits [1].
Characteristic manifestations include foot drop, cross-threshold gait, bowed feet, \”crane legs\”, and clumsy hand movements.
Physical examination
The physician may ask the patient to expose the muscles of the extremities to check for muscle atrophy.
The doctor may ask the patient to lie down and then lift his or her legs with some resistance to check the strength of the lower limbs.
The doctor may ask the patient to hold his or her hands or fingers tightly to check the strength of the hands and upper limbs.
The doctor may ask the patient to do some fine movements, such as fastening buttons, to check the patient\’s hand muscle mobility.
The doctor may observe the patient\’s gait when walking to see if there are any gait abnormalities.
The doctor may lightly prick the skin of the patient\’s limb with an object such as a slightly sharp bamboo skewer to check the patient\’s sensory function.
Screening Tests
Laboratory Tests
These include routine blood tests, liver and kidney functions, and blood electrolyte measurements.
The purpose is to assess the physical condition and also to make a pre-operative assessment for possible surgical treatment.
Neuroelectrophysiologic examination
Includes electromyography, nerve conduction velocity, etc.
The purpose is to understand the cause of muscle atrophy, changes in nerve conduction velocity, and to assist in making a definitive diagnosis [7].
Genetic testing
Genetic testing is important for the diagnosis and typing of the disease.
Mutations in the PMP22, MPZ, GJB1 and MFN2 genes account for a large proportion of the disease, and potentially relevant genes can be selected for sequencing and testing based on the patient\’s clinical and neurophysiological characteristics [8]. Whole exome testing can also be done
Pathologic testing
With the use of genetic testing methods, neuropathologic biopsy is not necessary in the vast majority of suspected cases. However, when clinical and electromyographic atypia are present, a nerve biopsy can be performed to assist in the differential diagnosis.
Imaging
If surgical orthopedic treatment is required, preoperative radiographs should be performed on all patients: these include anterolateral ankle joints, anterolateral and oblique positions of the foot, long-axis position of the heel bone, and orthostatic radiographs of the lower extremities [3].
Sometimes it may be necessary to do CT or magnetic resonance examination of the above joints and limbs to provide a detailed and accurate basis for surgical design.
Precautions:
CT is radioactive and children and pregnant women should be examined with caution.
Before MRI examination, if you have metal dentures, heart stents and other metal implants in your body, consult your doctor whether you can perform the examination.
Differential Diagnosis
Distal muscular dystrophy
Similarities: Both manifest as muscle atrophy and muscle weakness in the distal limbs.
Differences: The electromyogram of peroneal muscular dystrophy shows neurogenic changes and abnormal motor nerve conduction velocity, while the electromyogram of distal muscular dystrophy shows myogenic changes and normal motor nerve conduction velocity.
Hereditary ataxia with myasthenia gravis
Similarities: both have slowly progressive peroneal muscle atrophy, muscle weakness, bowed feet, hyperalgesia, and slowed nerve conduction velocity.
Differences: In hereditary ataxia with myasthenia gravis, in addition to the above symptoms, there are deficits in joint positional and vibratory sensation, sensory ataxia and postural tremor.
Chronic inflammatory demyelinating polyradiculoneuropathy
Similarities: Both may present with muscle weakness and muscle atrophy in the distal limbs.
Differences: Chronic inflammatory demyelinating polyradiculoneuropathy progresses relatively quickly, usually reaching its peak in more than 2 months. There are nerve conduction blocks on electromyography and increased protein in cerebrospinal fluid tests.
Treatment
Treatment aims: to increase independent mobility, improve quality of life, and minimize the occurrence and development of disability [9].
Treatment principle: based on the combination of rehabilitation therapy, wearing orthotics, surgical orthopedic surgery, and medication.
Rehabilitation therapy
Rehabilitation therapy is predominant in peroneal muscular dystrophy to improve walking ability and quality of life. It includes strength training and stretching to maintain muscle strength and prevent atrophy, as well as appropriate assistive devices (orthotics) to encourage patient mobility and improve safety [2].
Exercise is an important part of rehabilitation and includes endurance training, strength training, and stretching to maintain muscle strength, increase aerobic capacity, improve fitness, maintain range of motion, and avoid joint contractures.
Endurance training and strength training focus on proximal uninvolved muscles, such as knee extension, hip extension and abduction, in order to increase compensation for distal muscle weakness during walking and improve motor function.
Aerobic exercise training is an important part of rehabilitation therapy to reduce the risk of falls by improving core muscle strength and enhancing self-adjustment.
Orthotic Therapy
Foot deformity, foot drop, and Achilles tendon contracture are notable clinical features of patients with peroneal muscular dystrophy, so individualized orthotic therapy is critical [10].
Orthotics can improve patients\’ postural control, maintain postural stability, and reduce the energy consumption of exercise
There are many types and materials of ankle-foot orthoses available in the clinic, as well as orthopedic shoes, neoprene bunion-to-palm splints, and so on.
They need to be customized according to the patient\’s muscle strength, functional status and needs in order to achieve optimal comfort.
Surgical orthopedic treatment
Indications for surgery
Incompetent non-surgical treatment, rapid progression of the disease or severe deformity, foot and ankle deformity can not wear orthotics.
The foot cannot land flatly in an orthotic support, with obvious symptoms.
People with significant gait disturbances, such as difficulty walking, which severely limits daily life.
Patients with recurrent musculoskeletal complications (e.g., trips and falls) and severe pain due to foot and ankle deformities [3].
Surgical approach
Muscle balancing surgery, soft tissue release and orthotics, heel osteotomy and orthotics, management of the gastrocnemius complex, 拇-toe orthotics, and forefoot and midfoot osteotomy and orthotics.
Postoperative precautions
Rehabilitation exercises should still be carried out strictly according to medical advice after surgery.
Medication
Antidepressant drugs: For patients with obvious symptoms of anxiety and depression, antidepressant and anxiety drugs such as selective 5-hydroxytryptamine reuptake inhibitors and tricyclic antidepressants can be used. Tricyclic antidepressants can also be used in patients with neuropathic pain [2].
Prognosis
Cure.
Symptomatic treatment is currently the mainstay, and there is no complete cure for peroneal muscular dystrophy.
Prognostic factors
Peroneal muscular atrophy often progresses slowly and may severely impair activity in later stages, but rarely leads to total disability and does not affect normal life expectancy.
The prognosis is related to when diagnosis and treatment begin; the earlier the diagnosis and treatment, the better the patient\’s motor function is preserved and the better their quality of life.
Hazards
Usually patients\’ foot and ankle deformities progressively worsen with the development of the disease, and most patients need to undergo surgical treatment, which reduces the quality of life of patients and increases the financial burden of families.
Patients often suffer from neuropathic pain, fatigue, depression and anxiety, which likewise severely affect quality of life.
Daily
Daily Management
Dietary management
Balanced nutrition, with high quality protein, low fat, low salt, low oil and high fiber diet.
Avoid spicy, stimulating and overly oily food, and do not overeat.
Quit smoking and drinking, and do not drink strong tea and coffee.
Life management
When the patient\’s limbs are weak and activities are easy to fall, protective measures should be strengthened to prevent head and limbs from trauma and fracture injuries caused by falling.
Control weight, avoid obesity to increase the activity burden and lower limb joint damage.
Psychological support
Family members should guide patients to correctly understand the disease and establish confidence in the treatment of the disease.
When patients are found to have obvious anxiety and depression, they should seek help from the medical staff for psychological counseling in time, so as not to affect the therapeutic effect due to psychological problems.
Disease monitoring
Patients taking oral antidepressants need regular monitoring of blood routine and liver function.
Patients\’ limb weakness and the progress of foot and ankle joint injury should be monitored.
Prevention
The disease is hereditary, and genetic counseling based on genetic diagnosis can effectively reduce the birth of children with the disease.
Patients should avoid the use of drugs with peripheral neurotoxic effects to avoid aggravating peripheral nerve damage, such as metronidazole, nucleoside analogs, and furotoxin, as well as chemotherapeutic drugs such as cisplatin, oxaliplatin, perphenazine, and paclitaxel derivatives [2].