Proximal myopathy

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💪 About

• Weakness affects the proximal muscles (shoulders, hips, thighs, upper arms).
• Patients struggle with rising from a chair, climbing stairs, or lifting arms overhead.
• Often indicates an underlying systemic, endocrine, or inflammatory disorder.

🔎 Common Causes

• 🦴 Hypocalcaemia / Osteomalacia: Vitamin D or calcium deficiency → bone pain + muscle weakness.
• 🦋 Thyroid Disease: Both hyperthyroidism and hypothyroidism may cause myopathy (check TFTs).
• 💊 Steroid Use / Cushing’s Syndrome: Chronic steroids or cortisol excess → muscle atrophy.
• 🔥 Myositis: Inflammatory muscle disease (CK elevated; can be drug-induced e.g. statins).
• 🧬 Polymyositis: Autoimmune inflammatory myopathy, progressive proximal weakness.
• ⚡ Myasthenia Gravis: Fatigable weakness due to neuromuscular junction dysfunction.

🩺 Clinical Features

• Difficulty rising from a chair or lifting arms above head.
• 🚶 Waddling gait.
• Struggles with climbing stairs.

🧪 Investigations

• 🔬 Bloods: FBC, U&E, calcium, magnesium, CK.
• 🦋 Thyroid Function Tests (TFTs): To exclude thyroid disease.
• 🦴 Bone profile: ALP, calcium, phosphate, vitamin D (osteomalacia).
• 🧪 Liver function / cortisol: Consider Cushing’s (24h urinary cortisol, dexamethasone suppression).
• 🧬 Autoimmune panel: If myositis suspected.

📊 Common Causes of Proximal Myopathy

Cases - Proximal Myopathy

• Case 1 - Steroid-Induced Myopathy 💊: A 58-year-old woman on long-term prednisolone for polymyalgia rheumatica complains of difficulty rising from a chair and climbing stairs. Exam: proximal lower limb weakness, no pain, normal reflexes. CK normal. Diagnosis: Steroid-induced proximal myopathy. Management: Gradual steroid reduction if possible, physiotherapy, switch to steroid-sparing agent.
• Case 2 - Hypothyroid Myopathy 🦋: A 45-year-old woman with weight gain, lethargy, and cold intolerance presents with proximal muscle weakness and cramps. Exam: slow reflex relaxation, dry skin, periorbital puffiness. CK mildly elevated. Diagnosis: Hypothyroid myopathy causing proximal weakness. Management: Levothyroxine replacement; symptoms usually improve within months.
• Case 3 - Polymyositis (Inflammatory) 🔥: A 50-year-old man reports progressive weakness in shoulders and thighs over 3 months, struggling to lift objects overhead. Exam: symmetrical proximal weakness, tender muscles. CK markedly elevated. EMG: myopathic pattern. Diagnosis: Polymyositis. Management: High-dose corticosteroids, immunosuppressants (azathioprine, methotrexate), physiotherapy.
• Case 4 - Vitamin D Deficiency (Osteomalacia) 🌥️: A 30-year-old woman who wears concealing clothing develops bone pain and proximal muscle weakness, with waddling gait. Bloods: low vitamin D, low calcium, high ALP. Diagnosis: Osteomalacia with proximal myopathy. Management: Vitamin D and calcium supplementation; lifestyle advice.
• Case 5 - Cushing’s Syndrome (Endocrine) 🎭: A 40-year-old man presents with truncal obesity, purple striae, and easy bruising. He has difficulty climbing stairs. Exam: proximal weakness in hip flexors. CK normal. Diagnosis: Proximal myopathy due to hypercortisolism (Cushing’s). Management: Treat underlying cause (adrenal/ACTH-secreting tumour, iatrogenic steroids).

Teaching Commentary 🧠

Proximal myopathy = symmetrical weakness of shoulder and hip girdle muscles, often noticed as difficulty climbing stairs, rising from chairs, or combing hair. Reflexes are usually preserved. Key causes: - Endocrine: hypothyroid, hyperthyroid, Cushing’s, diabetes. - Drugs/toxins: corticosteroids, statins, alcohol. - Inflammatory: polymyositis, dermatomyositis. - Nutritional/metabolic: vitamin D deficiency, hypokalaemia. - Inherited: muscular dystrophies. Investigations: CK, thyroid function, cortisol, vitamin D, autoimmune myositis panel, EMG, and sometimes muscle biopsy. Management is always cause-directed, with supportive physio and occupational therapy.