Muscle Dystrophy Jon Durrani DO Attending Neurologist Dayton

Muscle Dystrophy Jon Durrani, DO Attending Neurologist Dayton Center for Neurologic Disorders

What is Muscle Dystrophy? • Essentially a group of muscle wasting disorders that cause a breakdown and subsequent of skeletal muscle over time. • There is great variability among the various dystrophies, including the muscle groups effected, the degree of weakness, the rate of decline, and the when the symptoms first appear. • Despite all the technology of today, there is no known cure yet discovered.

Types of Muscle Dystrophy • There are nine main categories of muscle dystrophy, within those categories there are more than thirty types of specific muscle dystrophies that can be diagnosed. • This discussion today will focus on the three main ones likely to be seen in practice: Duchenne Muscle Dystrophy (DMD), Becker Muscle Dystrophy, and Myotonic Dystrophy.

General Symptoms of Muscle Dystrophy • Poor Balance • Scoliosis • Progressive inability to walk

General Symptoms of Muscle Dystrophy • Progressive muscle wasting of skeletal muscles

General Symptoms of Muscle Dystrophy • Waddling gait

General Symptoms of Muscle Dystrophy • Calf deformation • Limited range of movement • Respiratory difficulty • Cardiomyopathy • Muscle Spasms

General Symptoms of Muscle Dystrophy • Gower's sign

Causes of Muscle Dystrophy • Generally speaking, these are inherited genetic disorders. • There are many patterns of inheritance and very from each subtype of muscle dystrophy, and can be X-linked, recessive, or dominant. • There are rare instances where there is de novo mutations within the individual with on family history of muscle dystrophy.

Diagnosis of Muscle Dystrophy • History of the patient and family members that may have been affected. • Initial testing of muscle testing includes a physical examination, look for the aforementioned signs and symptoms. • Additionally, further investigation includes muscle biopsy, CK testing, EMG, and genetic testing.

Diagnosis of Muscle Dystrophy • Additionally, Chest X-rays, Echocardiogram can be performed as well.

Treatment of Muscle Dystrophy • Even in 2018, unfortunately we do not have a cure for muscle dystrophy. • The main stays of treatment today are: • • • Physical therapy Occupational Therapy Orthortic Intervention (AFO, etc. ) Speech Therapy Respiratory Therapy Steroids (Prednisone)

Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy • X-linked recessive, 1: 3300 males • Xp 21, dystrophin gene mutation (2/3 familial, 1/3 new mutations) • Females with a single copy of the gene may show mild symtpoms • Typically presents at 5 years old • difficulty running • abnormal gait (waddling) • historic motor delay

Duchenne Muscular Dystrophy • Physical Exam: • Musculoskeletal • Lumbar lordosis • Pseudohypertrophy (enlarging) of tongue and calf muscles. The muscle tissue is eventually replaced by fat and connective tissue, hence the term pseudohypertrophy.

Duchenne Muscular Dystrophy • Neurologic Exam: • Neck flexor weakness • Symmetric and proximal UE and LE weakness, LE > UE • Diffuse hypotonia, DTRs 1+ diffusely

Duchenne Muscular Dystrophy • Other system involvement • Dystrophin is found in skeletal muscle, smooth muscle, cardiac muscle and brain • May have cognitive impairment • All develop cardiomyopathy • Cardiac involvement may require a pacemaker • May develop intestinal pseudo-obstruction • Higher risk of neurobehavioral disorders (e. g. , ADHD), learning disorders (dyslexia), and non-progressive weaknesses in specific cognitive skills (in particular short-term verbal memory), which are believed to be the result of absent or dysfunctional dystrophin in the brain.

Duchenne Muscular Dystrophy • Diagnosis • • CK elevated (10 x upper limit normal) Muscle biopsy (absent dystrophin) Genetic/DNA testing +/- EMG/NCV

Duchenne Muscular Dystrophy • Prognosis • • Supportive care +/- steroids Wheelchair bound by 13 years old Death in 20 s from respiratory or cardiac failure

Becker Muscle Dystrophy

Becker Muscle Dystrophy • Same pathogenesis as DMD • Except for inframe mutations for BMD, out of frame for DMD

Becker Muscle Dystrophy • Slower course • Present between 5 -15 years old • Wheelchair bound after 16 years old • Live through their 30 s-40 s

Becker Muscle Dystrophy • Less severe course, less likely to have • • • Cognitive impairment Cardiac disease Contractures Scoliosis GI issues

Becker Muscle Dystrophy • CK elevated (5 x upper limit of normal) • Muscle biopsy with decreased dystrophin

Congenital Myotonic Dystrophy

Congenital Myotonic Dystrophy • Autosomal Dominant • > 1000 CTG repeats in the DMPK gene, 19 q 13. 3 (anticipation) • Mom is typically the affected parent (check her grip!)

Congenital Myotonic Dystrophy • Poor fetal movement, polyhydramnios • Feeding and respiratory difficulties, cognitive • impairment, developmental delay

Congenital Myotonic Dystrophy • There are two kinds of Myotonic Dystrophy • DM 1 and DM 2 • DM 1 has an error in the DMPK gene. • DM 2 has an error in CNBP gene.

Congenital Myotonic Dystrophy • Neurologic Exam: • • Facial diplegia Hypotonia Decreased DTRs Intellectual disability

Congenital Myotonic Dystrophy • Other Physical Exam findings: • Joint deformities, from clubfoot to arthrogryposis • Cataracts • Heart Conduction problems

Congenital Myotonic Dystrophy • No clinical or EMG myotonia until 2 years of age • Genetic testing

Congenital Myotonic Dystrophy • Treatment • There is no treatment for myotonic dystrophy • Pain can be treated with tricyclic antidepressants (Amitryptiline, Nortyptiline) or NSAIDs • Associated Sleep Apnea – OSA, CSA treated with appropriate devices. • Orthotics • Physical Therapy

Muscle Dystrophy • The future: • Research Currently in the United States and the UK with gene research and neuromuscular regeneration.