McArdle Disease Misdiagnosed as Meningitis

Abstract

Patient: Female, 44Final Diagnosis: McArdle diseaseSymptoms: Exercise intolerance • muscle contracture • myalgia • myoglobinuria • recurrent rhabdomyolysisMedication: —Clinical Procedure: —Specialty: NeurologyObjective:Rare diseaseBackground:McArdle disease is a glycogen storage disorder mainly characterized by exercise intolerance. Prolonged muscle contracture is also a feature of this condition and may lead to rhabdomyolysis (RM), which is a serious event characterized by acute skeletal muscle damage.Case Report:A 44-year-old female patient presented with an acute contracture of the posterior neck muscles, causing severe nuchal rigidity. The contracture was induced during a dental extraction as she held her mouth open for a prolonged period, with her neck in a rigid position. She presented with severe pain in her ear and head, as well as fever, vomiting, and confusion. Based on her symptoms, she was initially misdiagnosed with bacterial meningitis and experienced an acute allergic reaction to the systemic penicillin she was subsequently administered. Lumbar puncture results were normal. High serum creatine kinase (CK) levels, recurrent exercise-related muscle symptoms, and a previous history of recurrent myoglobinuria raised the suspicion of an underlying neuromuscular condition. McArdle disease was confirmed by muscle biopsy and a genetic test, which revealed that the patient was homozygous for the R50X mutation in the PYGM gene.Conclusions:This case illustrates that even seemingly innocuous movements, if rapid isotonic or prolonged isometric in nature, can elicit a muscle contracture in McArdle disease patients. Here, we highlight the need for careful management in this patient population even during routine healthcare procedures. The allergic reaction to antibiotics emphasises that misdiagnoses may result in iatrogenic harm.

Misdiagnosis is an important factor for diagnostic delay in McArdle disease

“…Of the 45 patients who were misdiagnosed, 21 (47%) received incorrect management, with 13 (29%) receiving inappropriate exercise training advice (e.g. being advised to ignore symptoms of pain during exercise, or alternatively, being advised to avoid exercise altogether) and 12 (27%) receiving another medical intervention including antibiotic prescription, sternum surgery, tonsillectomy and invasive procedures such as cystoscopy [2]. Inappropriate exercise prescription that was too intense following a misdiagnosis of "laziness/being unfit" resulted in muscle damage and RM in a few patients.…”

“…Muscle pain occurs within a few minutes of starting physical activity and can lead to muscle contracture and rhabdomyolysis (RM) if that activity persists or is more vigorous. Muscle contracture and RM in McArdle disease do not just follow exercise and can also be triggered by sustained isometric muscle contraction in everyday activities or 'unusual' circumstances [1,2]. RM may result in potential life-threatening complications requiring urgent hospital admission such as compartment syndrome and acute kidney failure (Table 1).…”

Results of an open label feasibility study of sodium valproate in people with McArdle disease

“…[1][2][3][4] whichThis results in severe impairment of physical activity, especially when the onset of exercise is abrupt, high intensity or isometric in nature. 5, Currently,y, there is no satisfactory drug treatment for McArdle disease.…”