Charcot-Marie-Tooth disease

Pain Phenotypes in Rare Musculoskeletal and Neuromuscular Diseases

For patients diagnosed with a rare musculoskeletal or neuromuscular disease, pain may transition from acute to chronic; the latter yielding additional challenges for both patients and care providers. We assessed the present understanding of pain across a set of ten rare, noninfectious, noncancerous disorders; Osteogenesis Imperfecta, Ehlers-Danlos Syndrome, Achondroplasia, Fibrodysplasia Ossificans Progressiva, Fibrous Dysplasia/McCune-Albright Syndrome, Complex Regional Pain Syndrome, Duchenne Muscular Dystrophy, Infantile- and Late-Onset Pompe disease, Charcot-Marie-Tooth Disease, and Amyotrophic Lateral Sclerosis. Through the integration of natural history, cross-sectional, retrospective, clinical trials, & case studies we described pathologic and genetic factors, pain sources, phenotypes, and lastly, existing therapeutic approaches. We highlight that while rare diseases possess distinct core pathologic features, there are a number of shared pain phenotypes and mechanisms that may be prospectively examined and therapeutically targeted in a parallel manner. Finally, we describe clinical and research approaches that may facilitate more accurate diagnosis, monitoring, and treatment of pain as well as elucidation of the evolving nature of pain phenotypes in rare musculoskeletal or neuromuscular illnesses.

The Role of Rehabilitation in the Management of Patients with Charcot-Marie-Tooth Disease: Report of Two Cases

BACKGROUND:

Charcot-Marie-Tooth (CMT) disease is a hereditary disease with signs of chronic non-progressive motor-sensory neuropathy which is characterised by symmetric muscle atrophy and weakness of the distal portion of lower extremities.

AIM:

The aim is to present two cases with peroneal muscular atrophy, applied rehabilitation procedures and rehabilitation outcome.

MATERIAL AND METHODS:

Patient DR, aged 51, and patient KH, aged 78. Both patients had weakness and pronounced atrophy of the distal portion of lower extremities, numbness down the legs, contractures in the ankles and walking difficulties. Evaluation of patients included a clinical examination, Barthel Index, Time Up and Go test, measurement of the ankle range of motion, and a manual muscle test. On admission, the Barthel Index score was 60 in the first case, and 80 in the second. The rehabilitation program included exercise therapy with for lower extremity, occupational therapy, stationary bicycle riding, galvanic current, water exercises, and ankle-foot orthoses for both legs.

RESULTS:

The therapy applied had no significant changes in the clinical neurological status of the patients, but yet it provided some improvement in ankle contractures, better mobility, and a more stable gait.

CONCLUSION:

The application of rehabilitation procedures in patients with Charcot-Marie-Tooth disease can improve their functional status and walking stability.

Rehabilitation in Charcot-Marie-Tooth disease type 1

Charcot-Marie-Tooth disease is the most common inherited peripheral neuropathy with a prevalence of approximately 1 in 2,500 [1]. The most common subtype is the autosomal dominant type 1A, which is caused by an intrachromosomal duplication on chromosome 17p11.2 [2,3]. A consecutive primary loss of the myelin sheath leads to secondary axonal degeneration. Characteristic clinical findings include distally pronounced muscle wasting, secondary skeletal deformities, sensory loss, and reduced deep tendon reflexes [4,5]. The individual clinical phenotypes vary, even among monozygotic twins [6]. They range from sub-clinical manifestations to rare cases of wheelchair-bound patients. Overall, the quality of life is significantly impaired [7]. Despite ongoing research, no curative treatments are currently available [8]. A recently published ascorbic acid trial showed no significant effect on the clinical phenotype of CMT1A patients [9,32,36]. Nevertheless, physical therapy and moderate exercises are proven to be positively disease-modifying. While a cure lies beyond the scope of physical therapy, it may prevent the rapid aggravation of the clinical phenotype [10,11,17]. Recent studies suggest that CMT patients experience physical as well as mental benefits from rehabilitation programmes, but they also perceive that the performed exercises were not specifically designed to their needs [11]. In fact, there is little evidence-based data and no common consensus on rehabilitation in patients suffering from Charcot-Marie-Tooth disease.

Charcot-Marie-Tooth disease: an overview of genotypes, phenotypes, and clinical management strategies

Charcot-Marie-Tooth (CMT) disease, which encompasses several hereditary motor and sensory neuropathies, is one of the most common neuromuscular disorders. Our understanding of the molecular genotypes of CMT and the resultant clinical and electrophysiological phenotypes has increased greatly in the past decade. Characterized by electrodiagnostic studies into demyelinating (type 1) and axonal (type 2) forms, subsequent genetic testing often provides an exact diagnosis of a specific subtype of CMT. These advancements have made diagnostic paradigms fairly straightforward. Still, the nature and extent of neuromuscular disability is often complex in persons with CMT, and no curative treatments are yet available. Genotypically homologous animal models of CMT have improved exploration of disease-modifying treatments, of which molecular genetic manipulation and stem cell therapies appear to be the most promising. Research is also needed to develop better rehabilitative strategies that may limit disease burden and improve physical performance and psychosocial integration. Clinical management should be multidisciplinary, including neurologists, physiatrists, neurogeneticists, neuromuscular nurse practitioners, and orthopedists, along with physical and occupational therapists, speech-language pathologists, orthotists, vocational counselors, social workers, and other rehabilitation clinicians. Goals should include maximizing functional independence and quality of life while minimizing disability and secondary morbidity.

Measuring Ankle Instability in Pediatric Charcot-Marie-Tooth Disease

Children with Charcot-Marie-Tooth disease frequently suffer ankle sprain and experience chronic ankle instability; however, no pediatric self-reported measures of chronic ankle instability exist. The aim was to modify and validate the most reliable measure of chronic ankle instability in adults: the Cumberland Ankle Instability Tool. The Cumberland Ankle Instability Tool-Youth was tested for reliability, construct validity, and sensitivity to discriminate between 104 children aged 8 to 16 years: 31 children with Charcot-Marie-Tooth disease, 31 unaffected children with a history of ankle sprains, and 42 controls. Children with Charcot-Marie-Tooth disease had lower scores compared to unaffected children with a history of sprains (χ2 = 15.10; P < .001) and controls (χ2 = 33.69; P < .001). Scores moderately correlated to visual analog scale scores of ankle steadiness (r s = 0.684; P < .001), and "good" test-retest reliability was identified (ICC2,1 = 0.73). The Cumberland Ankle Instability Tool-Youth demonstrated excellent sensitivity and construct validity, identifying chronic ankle instability as a common problem for children with Charcot-Marie-Tooth disease.

Clinical approach to the diagnostic evaluation of hereditary and acquired neuromuscular diseases

For diagnostic evaluation of a neuromuscular disease, the clinician must be able to obtain a relevant patient and family history and perform focused general, musculoskeletal, neurologic, and functional physical examinations to direct further diagnostic evaluations. Laboratory studies for hereditary neuromuscular diseases include the relevant molecular genetic studies. The electromyogram and nerve-conduction studies remain an extension of the physical examination, and help to guide further diagnostic studies such as molecular genetics and muscle and nerve biopsies. All diagnostic information needs are to be interpreted within the context of relevant historical information, family history, physical examination, laboratory data, electrophysiology, pathology, and molecular genetics.

Motor Chip: A Comparative Genomic Hybridization Microarray for Copy-Number Mutations in 245 Neuromuscular Disorders

BACKGROUND

Array-based comparative genomic hybridization (aCGH) is a reference high-throughput technology for detecting large pathogenic or polymorphic copy-number variations in the human genome; however, a number of quantitative monogenic mutations, such as smaller heterozygous deletions or duplications, are usually missed in most disease genes when proper multiplex ligation-dependent probe assays are not performed.

METHODS

We developed the Motor Chip, a customized CGH array with exonic coverage of 245 genes involved in neuromuscular disorders (NMDs), as well as 180 candidate disease genes. We analyzed DNA samples from 26 patients with known deletions or duplications in NMDs, 11 patients with partial molecular diagnoses, and 19 patients with a clinical diagnosis alone.

RESULTS

The Motor Chip efficiently confirmed and refined the copy-number mutations in all of the characterized patients, even when only a single exon was involved. In noncharacterized or partially characterized patients, we found deletions in the SETX (senataxin), SGCG [sarcoglycan, gamma (35kDa dystrophin-associated glycoprotein)], and LAMA2 (laminin, alpha 2) genes, as well as duplications involving LAMA2 and the DYSF [dysferlin, limb girdle muscular dystrophy 2B (autosomal recessive)] locus.

CONCLUSIONS

The combination of exon-specific gene coverage and optimized platform and probe selection makes the Motor Chip a complementary tool for molecular diagnosis and gene investigation in neuromuscular diseases.

Diagnosis, natural history, and management of Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease is the most common inherited neuromuscular disorder. There have been substantial advances in elucidating the molecular bases of this genetically heterogeneous neuropathy and, in most cases, molecular diagnosis is now possible. The diagnostic approach requires careful assessment of clinical presentation and mode of inheritance, nerve-conduction studies, and DNA testing, and current research is focused on assessing natural history and finding effective treatments. Disease course is variable because of genotypic and phenotypic heterogeneity. At present, there is no drug therapy for Charcot-Marie-Tooth disease, and rehabilitation therapy and surgical procedures for skeletal deformities are the only available treatments, although best practice has not been defined. Animal models are proving useful for the identification of therapeutic targets and approaches. Progesterone antagonists, neurotrophic factors, ascorbic acid, and curcumin have shown promising results in experimental models, and ascorbic acid is being studied in large randomised controlled trials.

Natural history and treatment of peripheral inherited neuropathies

Charcot-Marie-Tooth disease (CMT) is genetically highly heterogeneous. Disease course and severity vary according to CMT type, causative gene, and mutation type, but considerable phenotypic variability may occur also for the same CMT type. Research is focused on possible modifier factors particularly in CMT1A associated with Peripheral Myelin Protein 22 (PMP22) overexpression. Natural history studies are important to define disease course in different CMT types and to allow better assessment of intervention efficacy. Only a few such studies have been carried out, mainly on CMT1A, and described impairment and disability progression. Motor potential amplitudes seem to correlate with disease severity and progression, suggesting that axonal loss is the basis of disability in CMT. There is need to develop suitable and reproducible outcome measures: the CMT Neuropathy Score is the only validated outcome score specific for CMT, but others have been tested during the last few years. Currently there is no effective drug therapy for CMT and supportive treatment is limited to physical therapy, orthotics, surgical treatment of skeletal deformities and soft tissue abnormalities, and symptomatic drug treatment. Research is focused on developing new treatment strategies and approaches. The progesterone antagonist onapristone proved to be effective in a rat model of CMT1A; unfortunately, currently available progesterone antagonists are too toxic to be safely administered to patients. Neurotrophin-3 (NT3), a neurotrophic factor known to promote axonal growth, was tested with favourable results in two animal models and in a pilot study involving eight CMT1A patients. Ascorbic acid (AA) administration to CMT1A mice improved clinical and neuropathological findings, possibly by down-regulating PMP22 through a cAMP mediated mechanism. Clinical trials of AA in the human disease are currently being performed. Curcumin stimulates translocation of misfolded protein from the endoplasmic reticulum and proved useful for selected myelin protein zero and PMP22 mutants in vitro and in the animal models Trembler and TremblerJ.