Patient Case: Inclusion Body Myositis (IBM)
A 68-year-old male presents to the neurology clinic with a slowly progressive muscle weakness over the past five years. He initially noticed difficulty gripping objects and frequent falls due to knee buckling. Over time, he developed weakness in both his hands and legs, making it hard to open jars, button his shirt, or climb stairs. He denies muscle pain, sensory loss, or swallowing difficulties but reports mild weight loss.
Medical History & Social Background
• Medical history: Hypertension, type 2 diabetes.
• Family history: No known neuromuscular disorders.
• Occupation: Retired construction worker, previously very active.
• Social history: Non-smoker, occasional alcohol use.
Physical Examination
• Neuromuscular:
√. Asymmetric muscle weakness affecting both proximal and distal muscles (notably quadriceps and finger flexors).
√. Handgrip weakness with difficulty making a fist.
√. Mild atrophy of forearm and thigh muscles.
√. Deep tendon reflexes reduced in lower limbs.
√. Normal sensation and coordination.
• Cranial nerves: Intact; no facial or bulbar weakness.
Laboratory & Diagnostic Findings
• Creatine kinase (CK): Mildly elevated (600 U/L, normal <200 U/L).
• Antinuclear antibody (ANA): Negative.
• Anti-cN1A antibodies: Positive (specific for IBM).
• Electromyography (EMG): Mixed myopathic and neurogenic changes.
• Muscle biopsy:
√. Rimmed vacuoles, inclusion bodies, and chronic inflammatory infiltrates confirming inclusion body myositis.
Diagnosis
The insidious onset of asymmetric distal and proximal muscle weakness, finger flexor and quadriceps involvement, slow progression, and biopsy findings confirm a diagnosis of inclusion body myositis (IBM).
Management Plan
1. Supportive care (since IBM does not respond well to immunosuppressive therapy):
• Physical therapy to maintain mobility and prevent falls.
• Occupational therapy to assist with hand function (e.g., grip aids).
• Swallowing evaluation if dysphagia develops.
2. Symptom management
• Assistive devices (e.g., cane, walker, braces) to reduce fall risk.
• Speech therapy if swallowing becomes affected.
3. Monitoring & Long-Term Care
• Regular muscle strength assessments.
• Evaluation for dysphagia and respiratory function in later stages.
Challenges & Considerations
• IBM is slowly progressive and does not respond well to corticosteroids or immunosuppressive therapies.
• Patients often develop severe disability over time but typically maintain independence for several years.
• Risk of aspiration pneumonia if dysphagia worsens.
Prognosis
IBM is a chronic, slowly progressive disease that does not significantly shorten lifespan but can lead to severe functional disability. Supportive care is the mainstay of management.
A) Polymyositis
B) Amyotrophic lateral sclerosis (ALS)
C) Inclusion body myositis (IBM)
D) Dermatomyositis
A) Symmetric proximal muscle weakness
B) Rapid progression over months
C) Distal and proximal muscle involvement, especially finger flexors and quadriceps
D) Facial and bulbar muscle involvement early in the disease
A) Muscle biopsy
B) Anti-Jo-1 antibody test
C) Serum creatine kinase (CK) levels
D) Brain MRI
A) High-dose corticosteroids
B) Intravenous immunoglobulin (IVIG)
C) Physical therapy and supportive care
D) Methotrexate
