Module 3: Myasthenia Gravis (MG)
What is Myasthenia Gravis?
- Chronic autoimmune, neuromuscular disease that causes weakness in the skeletal muscles that worsens after periods of activity and improves after periods of rest. - Fluctuating weakness of the voluntary muscle groups. The immune system mistakenly attacks and destroys the body's own tissues by forming autoantibodies. - Progressive
When working on muscle strength and range of motion with Myasthenia Gravis patients ...
- Must be performed in a manner to limit any over-exertion - Proximal strengthening priority, resistance bands, ankle weights - Sidestepping
When treating someone with MG, what are some appropriate interventions?
- Recumbent biking at moderate intensity, with RPE at 13 - Education on fall prevention and training on floor transfers - Sidestepping with theraband and proximal LE strengthening
Pathophysiology of Myasthenia Gravis
-- Abnormal immune reaction (antibody-mediated autoimmune response) in which the body's immune defenses (i.e., antibodies) inappropriately attack certain receptors in muscles that receive nerve impulses. -- Anti-acetylcholine receptor antibodies (anti-AChR) ATTACK Decreased # of ACh receptors failed nerve transmission at NMJ = deficiency or weakness of muscle contractions
Options for medical management of Myasthenia Gravis
1) Thymectomy 2) Monoclonal antibody 3) Anticholinesterase meds 4) Immunosuppresive drugs 5) Plasmaphersis and IVIg
Prevalence of Myasthenia Gravis
14-40 per 100,000 individuals Female's > males Sx onset peaks in women in 20's or 30's; men 50's or 60's
What percentage of acetylcholine receptors are affected by Myasthenia Gravis?
80 percent. (destroyed more rapidly than body can regenerate them)
Myasthenia Gravis occurs when antibodies attack the _________ receptors at the neuromuscular junction leading to ________?
Acetylcholine; muscle weakness
Lambert Eaton syndrome
Antibodies against voltage gated calcium channels of the NMJ. Associated with small cell long cancer.
Balance assessments for Myasthenia Gravis
BERG, Romberg, FIST (seated balance test)
Psychological assessments for Myasthenia Gravis
Beck Depression Inventory Myasthenia Gravis Quality of Life (MG-QOL15)
Endurance training for MG
Bike, NuStep, Arm Bike (UBE), walking
Possible cause of Myasthenia Gravis
Cluster of cells causes thymomas (can become cancerous) Scientists believe the thymus gland may give incorrect instructions to developing immune cells, causing the immune system to attack its own cells and tissues and produce acetylcholine receptor antibodies
Thymus Gland
Controls immune function Produces T lymphocytes or T-cells
Exacerbations Causes in Myasthenia Gravis
Drugs Overexertion Pregnancy Menstruation Emotional stress Infections (i.e. tooth abscesses, flu etc)
PT goals for Myasthenia Gravis
Energy Conservation Saving Devices Mobility with appropriate DME Fall Prevention Maximize function and QOL Recommend community programs/ support groups
How to progress strength training with Myasthenia Gravis patients?
Exercise large, proximal muscle groups for short periods of time, building up to moderate intensity
What is moderate intensity?
HR should not be elevated >30 bpm from resting baseline At peak exercise, pt should not have SOB MG sx are not worsened during exercise Recovery of fatigue <2 hours after exercise No severe muscle fatigue 2 days post exercise
Immunosuppressive drugs
Improve muscle strength by suppressing the production of abnormal antibodies
Origin of term: myasthenia graves
Latin and Greek in origin, means "grave, or serious, muscle weakness."
Myasthenia Gravis: PT Evaluation/Presentation
MMT testing/ROM Bed mobility/transfers Standing balance/sitting balance Gait (FGA, DGI, TUG) Endurance (30sSST, 5xSST, 6MWT, 2MWT) Fall risk DME recommendations Psychological
What level of intensity to use with Myasthenia Gravis patients?
Moderate levels of intensity are BEST, but may be able to increase in mild cases of Myasthenia Gravis
Gait training interventions for MG
Most appropriate AD Obstacles, hurdles, compliant surfaces, level ground, outdoors, stairs
Drugs that can exacerbate Myasthenia Gravis
Muscle relaxants during surgery aminoglycoside and quinolone antibiotics Cardiac anti-arrhythmics Local anesthetics Magnesium salts
Myasthenia Gravis: Prognosis
No "Cure" With treatment, most individuals with myasthenia gravis can significantly improve their muscle weakness and lead normal or nearly normal lives Some cases of myasthenia gravis may go into remission—either temporarily or permanently— and muscle weakness may disappear completely so that medications can be discontinued Stable, long-lasting complete remissions are the goal of thymectomy and may occur in about 50 percent of individuals who undergo this procedure.
Studies have shown that moderate to high intensity aerobic training and progressive resistance training are feasible for:
People with mild MG. Shows there is potential to progress past moderate.
Diagnostic tests for Myasthenia Gravis
Physical/Neuro Exam (Strength, tone, coordination, ocular impairment, sense of touch) Edrophonium Test Blood test (Abnormally elevated Ach receptor antibodies) Anti-MuSK antibody EMG Repeated stimulation to muscle fibers are not tolerated well in pt's with Myasthenia Gravis Imaging: CT or MRI Identify presence of thymoma Pulmonary Function Test Predictor of myasthenic crisis
5 Ps of energy conservation
Planning, Prioritize, Pacing, Positioning/Posture, Power/ Labor
MMT/ROM for Myasthenia Gravis
Proximal muscles most important Forward arm abduction time (up to 5 minutes)
Breathing and Postural Exercises for MG
Pursed Lip breathing, core strengthening
Thymectomy
Removes the Thymus gland to reduce sx or need for other therapies
Plasmapheresis and IVIg
Removes the destructive antibodies
Transfer training for MG
Sit to stands, SPT's etc
Anticholinesterase Meds
Slow the breakdown of acetylcholine at the NMJ
Balance training interventions for MG
Static: Romberg, staggered, tandem, SLS, eyes open/eyes closed, head movements, foam Dynamic: Uneven or compliant surfaces, walking with head movements, stepping to targets, BOSU, Rocker board, cone taps Ankle, hip and stepping strategies
Monoclonal antibody
Targets the process by which the acetylcholine antibodies injure the NMJ
Edrophonium Test
Tests ocular muscle weakness
ptosis
drooping
Myasthenic crisis
medical emergency that requires management in an intensive care unit. Exacerbation of weakness sufficient to endanger life; it usually consists of respiratory failure caused by diaphragmatic and intercostal muscle weakness. emergency respiratory assistance (assisted ventilation) temporary cessation of anticholinesterase therapy to exclude excessive dosage as a possible cause immediate treatment of possible causative infection with appropriate antibiotic medication or other therapy including plasmapheresis intravenous immunoglobulin, high dose prednisone
ocular myasthenia
muscle weakness of muscles of eye ptosis and diplopia
Symptoms of Myasthenia Gravis
weakness of the eye muscles drooping of one or both eyelids (ptosis) blurred or double vision (diplopia) a change in facial expression difficulty swallowing shortness of breath impaired speech (dysarthria) weakness in the arms, hands, fingers, legs, and neck.
