Neuromuscular diseases

Transcription

1 Neuromuscular diseases

2 Spinal muscular atrophy - SMA characterized by degeneration of the anterior horn cells in the spinal cord and motor nuclei in the lower brainstem. SMA type 1, is also known as Werdnig- Hoffmann disease. diffuse symmetric proximal muscle weakness that is greater in the lower than upper limbs and absent or markedly decreased deep tendon reflexes. SMA types 2 and 3 have later onset and are less severe.

3 Spinal muscular atrophy - SMA inheritance pattern of 5q-related SMAs is autosomal recessive. diagnosis of SMA is made clinically by electromyography and molecular genetic testing. treatment for SMA is supportive and directed at providing nutrition and respiratory assistance as needed, and treating or preventing complications of weakness. VPA, ventilation, orthopedic surgery

4 Charcot-Marie-Tooth type 1 hereditary demyelinating polyneuropathy type 1 axonal type 2 electrophysiologic features are often suggestive, but genetic testing is available. peroneal muscle atrophy electromyography molecular genetic testing Payrson, Marchesi 2009, s. 656

5 Disorders of the neuromuscular junction characterized by abnormal neuromuscular transmission, leading to muscle fatigability and weakness. are rare conditions include: transient acquired neonatal myasthenia, congenital myasthenia, toxicity caused by magnesium or aminoglycosides, and infant botulism.

6 Myasthenia gravis pseudoparalytica autoimmune disorder characterized by weakness and fatigability of skeletal muscles. muscle weakness is due to dysfunction of the neuromuscular junction electromyography; antibody-achr, MUSK tp. i-ache, imunosupression, thymectomy myasthenic - cholinergic crisis: IVIG, PE myasthenic syndromes (epsilon-achr)

7 Muscular dystrophies inherited group of progressive myopathic disorders resulting from defects in a number of genes required for normal muscle function muscle weakness is the primary symptom. DMD/BMD; LGMD; FSHD; EDMD; CMD merosin defect DM1,2 myotonic dystrophy

8 Duchenne and Becker muscular dystrophies inherited as X-linked recessive traits gene responsible for the production of dystrophin Duchenne muscular dystrophy (DMD) is associated with the most severe clinical symptoms Becker muscular dystrophy (BMD) has a similar presentation to DMD, but typically has a later onset and a milder clinical course

9 DMD causes: primary dilated cardiomyopathy (DCM) and conduction abnormalities progressive scoliosis develops in nearly all children with DMD Physical examination: pseudohypertrophy of the calf and (occasionally) quadriceps muscles, lumbar lordosis, a waddling gait, shortening of the Achilles tendons, and hyporeflexia or areflexia.

10 Duchenne and Becker muscular dystrophies serum creatine kinase (CK) and CK-MB, LD, AST, ALT, myoglobin concentrations are elevated. EMG, molecular genetic testing, sequence analysis to detect point mutations. muscle biopsy imunohistological and molecular genetic testing

11 Duchenne and Becker muscular dystrophies in addition to muscle weakness, cardiac, pulmonary, and orthopedic complications are frequently associated. spirometry, ECG, Echo, Holter. recommended bone-health assessments. orthopedic surgery. clinically apparent muscle weakness occurs in 2.5 to 20 % of female carriers of a mutated dystrophin gene.

12 Duchenne and Becker muscular dystrophies - treatment all boys with DMD who are ambulatory or in the early non-ambulatory stage participate in regular submaximum (ie, gentle) exercise glucocorticoids are the mainstay of treatment for DMD carnitin, vitamine E; creatine monohydrate has been studied for its potential to increase muscle strength

13 Duchenne and Becker muscular dystrophies - treatment Ataluren (PTC124) is an investigational orally administered drug being developed for the treatment of genetic defects caused by nonsense (stop) mutations. Ataluren promotes ribosomal read-through of nonsense (stop) mutations, allowing bypass of the nonsense mutation and continuation of the translation process to production of a functioning protein.

14 Duchenne and Becker muscular dystrophies - treatment investigational approach involves injection of antisense oligonucleotides that induce specific exon skipping during messenger RNA splicing, thereby correcting the open reading frame of the DMD gene and restoring dystrophin expression. deletion PRO 051

15 Muscular dystrophies Facioscapulohumeral muscular dystrophy (FSHD) is the third most common type of muscular dystrophy. FSHD is usually slowly progressive. Limb-girdle muscular dystrophy (LGMD) includes a number of disorders with heterogeneous etiologies. Patients with muscular dystrophy of girdle distribution, have a predominantly proximal distribution of weakness.

16 Emery-Dreifuss muscular dystrophy (EDMD) also known as humeroperoneal muscular dystrophy, can be inherited as an X-linked recessive, autosomal dominant or recessive disorder, the major features are early contractures, slowly progressive humeroperoneal muscle weakness/wasting, and a dilated cardiomyopathy associated with AVconduction abnormalities.

17 Muscular dystrophies Infants with congenital muscular dystrophy (CMD) are hypotonic and weak at birth and have findings consistent with muscular dystrophy on muscle biopsy. Congenital myopathies present from birth, although their expression may be delayed. present with hypotonia and weakness that is greater proximally than distally (nemaline myopathy, central core disease, myotubular myopathy).

18 Muscular dystrophies Myotonic dystrophy type 1 (DM1) and myotonic dystrophy type 2 (DM2) are multisystem disorders characterized by skeletal muscle weakness and myotonia, cardiac conduction abnormalities, cataracts, testicular failure, hypogammaglobulinemia, impaired sleep and excessive daytime sleepiness, and insulin resistance.

19 Muscular dystrophies The symptoms, signs, and laboratory abnormalities resulting from a metabolic myopathy vary with the underlying defect. Mitochondrial diseases are caused by pathologic dysfunction of the mitochondrial respiratory chain that present with a wide range of clinical expression. When skeletal muscle is affected, either alone or with central nervous system disease, the term mitochondrial myopathy is used.

20 Muscular dystrophies Juvenile dermatomyositis (JDM) and juvenile polymyositis (JPM) are rare autoimmune myopathies affecting children. JDM is characterized primarily as a capillary vasculopathy, whereas JPM involves direct T-cell invasion of muscle fibers similar to that seen in adult polymyositis