Giant cell arteritis has a wide variety of clinical symptoms, one of them being cervical radiculopathy, which mainly involves the C5 nerve root. If the patient does not develop typical clinical symptoms of giant cell arteritis but has C5 radiculopathy, it may be misdiagnosed as polymyalgia rheumatica or elderly-onset rheumatoid arthritis due to old age, high serum inflammatory markers, and difficulty in raising both upper limbs.
A 72-year-old Japanese man with a month-long history of dyspnea on exertion and with difficulty in raising both upper limbs was referred to our hospital because of elevated serum C-reactive protein (12.62 mg/dL). He had no typical symptoms of giant cell arteritis such as headache, jaw claudication, visual loss, and fever. The patient tested negative for rheumatoid factor and anti-cyclic citrullinated peptide antibody, and matrix metalloproteinase-3 was within the normal range (54.3 ng/mL). Musculoskeletal ultrasound examination showed absence of tenosynovitis, bursitis, and synovitis, and the patient did not meet the classification criteria of polymyalgia rheumatica or rheumatoid arthritis; hence, those two diseases were unlikely. A precise neurological examination suggested bilateral C5 and C6 anterior radiculopathy and left C4 radiculopathy. Since cervical magnetic resonance imaging showed no mechanical causality, cervical radiculopathy of unknown origin was suggested. Fluorodeoxyglucose positron emission tomography/computed tomography revealed increased fluorodeoxyglucose lineal uptake along the vessel walls, including temporal arteries, vertebral arteries, and axillary arteries. Results of the biopsy of the left superficial temporal artery were compatible with giant cell arteritis. He was successfully treated with 30 mg of prednisolone, and both upper limbs could be elevated.
If the patient was misdiagnosed with polymyalgia rheumatica or elderly-onset rheumatoid arthritis based on only clinical symptoms and laboratory data, his symptoms might not improve due to insufficient steroid dose and vascular complications may occur later. Although rare, peripheral neuropathy in giant cell arteritis may include cervical radiculopathy. The musculoskeletal ultrasound and precise neurological examination were the turning points for the diagnosis of this case, and making a careful diagnosis using these methods was important.