A 65-year-old woman comes to the physician complaining of periodic headaches in the temporal region, visual disturbances, and neck stiffness. Appropriate empiric medical therapy is initiated, and biopsy of a scalp artery confirms giant cell arteritis. The patient is very compliant with treatment. She comes to the physician 6 months later with slowly progressive muscle weakness. Her headaches have resolved, but she has difficulty climbing stairs and getting up from a chair. Her blood pressure is 120/70 mm Hg, pulse is 82/min, and respirations are 12/min. Physical examination shows 4/5 muscle power in her proximal lower extremities bilaterally. Her serum creatine kinase level and erythrocyte sedimentation rate are normal. Which of the following is the most likely cause of this patient's current complaints?

Question

A 65-year-old woman comes to the physician complaining of periodic headaches in the temporal region, visual disturbances, and neck stiffness.  Appropriate empiric medical therapy is initiated, and biopsy of a scalp artery confirms giant cell arteritis.  The patient is very compliant with treatment.  She comes to the physician 6 months later with slowly progressive muscle weakness.  Her headaches have resolved, but she has difficulty climbing stairs and getting up from a chair.  Her blood pressure is 120/70 mm Hg, pulse is 82/min, and respirations are 12/min.  Physical examination shows 4/5 muscle power in her proximal lower extremities bilaterally.  Her serum creatine kinase level and erythrocyte sedimentation rate are normal.  Which of the following is the most likely cause of this patient's current complaints?

Quizplus · Accepted Answer

11ec25c8_d293_c8db_bc81_5d1d7929775c_MD0003_00 This patient has a history consistent with temporal arteritis (ie, giant cell arteritis), which is treated with high-dose oral glucocorticoids tapered slowly over a prolonged period. Many patients develop complications of therapy due to the long duration of treatment with supra-physiological doses of glucocorticoids. In addition to hyperglycemia and bone loss, treatment may be associated with glucocorticoid-induced myopathy (GIM). GIM is one of the most common types of drug-induced myopathy and typically occurs weeks to months after starting glucocorticoid therapy. Acute myopathy following very high-dose pulse glucocorticoid therapy can occur in critically ill patients but is not as common as chronic myopathy complicating long-term glucocorticoid use. The mechanism is thought to be due to increased muscle catabolism and decreased anabolism as a direct effect of glucocorticoids. This risk of GIM rises with higher doses of glucocorticoids (generally >40 mg hydrocortisone daily or its equivalent). Patients typically develop painless proximal muscle weakness (lower extremity before upper extremity) that manifests as difficulty in daily activities such as getting up from a chair, climbing stairs, or brushing hair. There is no muscle inflammation or tenderness, and creatine kinase and erythrocyte sedimentation rate (ESR) are normal. Muscle power improves after discontinuation of glucocorticoids, but recovery can take weeks to months. (Choice B) Inflammatory myositis can present with symmetric proximal muscle weakness. However, the muscles are generally tender on palpation and creatine kinase and ESR levels are usually elevated. (Choice C) Mononeuritis multiplex is usually seen in vasculitis and is caused by nerve damage in 2 or more nerves in separate parts of the body. Patients typically develop asymmetric peripheral nerve findings such as wrist or foot drop. (Choice D) Multiple sclerosis typically presents with 2 or more episodes of various neurologic symptoms with interval resolution rather than chronic/progressive symptoms. (Choice E) Neuromuscular junction diseases such as myasthenia gravis may cause proximal muscle weakness. However, they usually cause more upper- than lower-extremity disease and usually have associated ocular symptoms. Muscle weakness is typically fluctuating; more muscle weakness is observed later in the day and following exercise. (Choice F) Polymyalgia rheumatica can be seen in up to 50% of patients with temporal arteritis. Patients typically complain of aching and morning stiffness, with pain and decreased range of motion in the shoulders, neck, and hip girdle. Patients have objectively normal muscle strength. The ESR is usually elevated >40 mm/hr. Symptoms improve rapidly (in days) with glucocorticoids, and ESR usually returns to normal in a few weeks. Creatine kinase is normal in patients with polymyalgia rheumatica. (Choice G) Symmetric polyneuropathies are characterized by paresthesias and predominantly distal, rather than proximal, muscle weakness. Educational objective: Glucocorticoid-induced myopathy is a complication of chronic corticosteroid use. It is characterized by painless proximal muscle weakness, which is more prominent in the lower extremities. There is no muscle inflammation or tenderness, and creatine kinase level and erythrocyte sedimentation rate are normal. Glucocorticoid-induced myopathy slowly improves once the offending medication is discontinued. References: Glucocorticoid-induced myopathy (http://www.ncbi.nlm.nih.gov/pubmed/20471889)

A 65-Year-Old Woman Comes to the Physician Complaining of Periodic