Myopathy

Myopathy

Dr. Maitham F. Jalal
F.I.B.M.S F.E.B.N

When you suspected myopathay

Proximal weakness
difficulty in going upstairs
difficulty combing hair
No parasthesia and numbness

• The first goal in approaching a patient with a suspected muscle disease is to determine :
• The the cause of the myopathy.
• To determine whether a specific treatment is available and if not, to optimally manage the patient’s symptoms , functional abilities and enhance quality of life.

ETIOLOGY / CLASSIFICATION

Inherited myopathies
Muscular dystrophies
Congenital myopathies
Inherited metabolic myopathies


Acquired myopathies
Inflammatory myopathies

Acquired metabolic myopathies

Toxic myopathies

Myopathies Presenting in Adulthood

Inherited

1 Muscular dystrophies

Limb-girdle
Facioscapulohumeral FSHD
Becker , DMD
Myotonia dystrophica

2 Metabolic myopathies

Acid maltase deficiency
Lipid storage diseases
Mitochondrial myopathies


3 Congenital myopathy
Nemaline myopathy

Acquired

1 Inflammatory myopathies
Polymyositis
Dermatomyositis
Inclusion body myositis

2 Endocrine( metabolic) myopathies

Thyroid

3 Toxic myopathies

Alcohol
Corticosteroids
Statin

What is Muscular Dystrophy?(MD)

• Muscular Dystrophy:
• group of genetic disorders that are characterized by progressive loss of muscle integrity, wasting, and weakness. Characterized by degeneration and regeneration of muscle fibers (in contrast with static or structural myopathies)
• Muscular Dystrophy Association
• Multisystem diseases : cardiac , respiratory GIT and cognitive


• the two most common and severe dystrophies

Duchenne Muscular Dystrophy

• Presentation: 3-5 y/o with pseudohypertrophy of calf muscles, frequent falls, tip toe walking , slow running, and waddling gait
• Other organs affected
• Heart – cardiomyopathy
• Respiratory
• Intellect - 30 % with impairment IQ
• Very high CPK

Myotonia Dystrophica

• Presentation – adult with multiple systems affected
• Primarily distal and facial weakness
• Facial features: frontal balding in men, ptosis, hatchet face ^ shaped upper lip
• Myotonia: difficulty in relaxation after contraction
• In addition :
• Heart: conduction block – evaluate syncope
• Brain: learning disabilities
• Ophthalmology: cataracts
• Endocrine: insulin resistance, hypothyroidism, testicular atrophy

Facioscapulohumeral FSHD

normal deltoids


biceps, triceps commonly weak, forearm muscles are less involved resulting in a
popeye-like appearance

Scapular winging may be very asymmetric (misdiagnosed as long thoracic nerve of palsy)

General Diagnostic Testing

Creatine kinase :
greatly elevated (50 times normal)
Increased in DMD
• nucleotide repeats …..dystrophen

• Steroids

• Briefly increase strength, slow progression in dystrophinopathy
• Creatine and glutamine may help delay
• progression/improve energy in youngest with DMD
• Physiotherapy , contracture prevention and surgeory
• Treat respiratory , cardiac


Idiopathic inflammatory myopathies

Polymyositis

Dermatomyositis

Inclusion body myositis

Clinical features
Progressive painful weakness

Difficulty lifting above head/combing hair

Difficulty arising from a low chair or toilet
Nasal regurgitation or choking when eating
Hoarseness, change in voice
*Ocular/facial muscle involvement is very uncommon
Symmetric weakness of limb girdle muscles and anterior neck flexors.

Fatigue

Fever


• Dermatologic features in dermatomyositis

Dermatologic manifestations

www.jfponline.com/Pages.asp?AID=2763&UID=

Inclusion body myositis

May differ from PM and DM :

Occur in elderly

focal, distal UL and proximal LL weakness.
Dyspagia is a late occurrence.
CK only slightly increased and can be normal in up to 25% of patients.

Multisystem disease

Cardiac
Respiratory involvement
fibrosis with anti –JO antibody
GIT
Autoantibody


Malignancy risk
Strong association between malignancy and dermatomyositis, but less clearly with polymyositis.
Ovarian, lung, pancreatic, stomach and colorectal and non-Hodgkin lymphoma
The overall risk is greatest in the first 3 years after diagnosis but is still increased through all years of follow-up.

Investigations

Muscle Biopsy
NCS/EMG
Lab ( CK)

• Electromyographic (EMG)

•

Corticosteroids is mainstay of treatment in most cases

Start 1-2 mg/kg/day
Continue until CPK returns to normal, then slow taper.
For severe acute disease, consider pulse dose steroids.

Other treatments

Steroid sparing
Methotrexate
Imuran
Non-responders
Rituxan
IVIG
Cyclosporin
Cyclophosphamide
Plasmapheresis


Corticosteroid- Corticosteroid-Induced Myopathy
Steroid myopathy is usually an insidious disease process that causes weakness mainly to the proximal muscles of the upper and lower limbs and to the neck flexors.
An excess of either endogenous or exogenous corticosteroids is believed to cause the condition. Excess endogenous corticosteroid production can arise from adrenal tumors.
An excess of exogenous corticosteroid can result from steroid treatment for asthma, chronic obstructive pulmonary disease, and inflammatory processes, such as polymyositis, connective tissue disorders, and rheumatoid arthritis

Corticosteroid- Corticosteroid-Induced Myopathy

Investigation

Serum levels of creatine kinase typically are within the normal range.

Electromyography (EMG) and nerve conduction studies (NCSs)
1. Motor and sensory NCS results typically are normal.
2. EMG studies reveal normal insertional without abnormal spontaneous activity (positivesharp waves and fibrillation potentials). Which is the main difference between inflammatory myopathy and myopathy result from steriod use in case of inflammatory myopathy

Corticosteroid- Corticosteroid-Induced Myopathy

Treatment
The main treatment recommendations for steroid myopathy are a decrease in the dose of steroid to below a threshold level or the discontinuation of the corticosteroid's use.
Alternate-day dosing could also be considered.
Another recommendation is that the currently administered steroid be exchanged for one that is not fluorinated.



THANK YOU