Carpal Tunnel Syndrome After Ciprofloxacin-Induced Tendinitis

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To the Editor: Different types of antibiotics can affect the peripheral nervous system and cause neuropathies, myopathies, and neuromuscular junction disorders by direct or indirect mechanisms.1 Fluoroquinolones may also cause seizures or encephalopathy, and a few cases of tendinitis have been reported as well.2-4 Tendinitis may occur as early as 2 hours after the first dose, and 50% of patients develop symptoms within 6 days of starting medication. Tenosynovitis has also been reported in association with recurrent carpal tunnel syndrome.5 We report a case of ciprofloxacin-related tendinitis leading to carpal tunnel syndrome A 77-year-old right-handed woman developed a urinary tract infection and was empirically treated with oral ciprofloxacin. Three days later, she developed bilateral hand pain and swelling, which improved after the medication was stopped and with a brief course of oral steroids and antihistamines. Symptoms were consistent with flexor tendinitis with focal tenderness and swelling. There was no history of diabetes, gout, rheumatoid arthritis, or of other autoimmune diseases. Because severe pain persisted waking her up, she was referred to a neurologist. At that time, 4 weeks after the onset and swelling resolved, the pain still involved the first three fingers, more severely on the left. She performed her daily activities independently, but pain got worse when these fingers were touched. She denied any neck or upper arm discomfort. On examination, she had slight atrophy and weakness of left thenar muscles (Medical Research Council 5-/5) with decreased sensation over distal aspects of the first three fingers on the left and left thenar allodynia. The remainder of the examination was normal. Electrodiagnostic testing was performed at 6 weeks after the onset and confirmed the diagnosis of bilateral distal median nerve entrapments (carpal tunnel syndrome) (Table 1), more severe on the left. Needle examination showed only few fibrillation potentials in the left abductor pollicis brevis muscle. The use of a wrist splint did not alleviate the symptoms. Repeat study 3 months later did not show significant improvement. Because symptoms persisted, she underwent bilateral sequential carpal tunnel releases resulting in resolution of her symptoms. Flexor tendinitis and inflammatory arthritis can precipitate median nerve entrapment in a confined space of carpal tunnel. Increased incidence of tendonitis has been described in elderly (older than 60 years of age) and with renal dysfunction or corticosteroid treatment.2-4 Most commonly, Achilles and patellar tendons are affected, but few cases of shoulder and hand tendinitis were reported. 2,3 Tendon rupture was reported in 5% of patients with quinolone-related tendinitis.2 Timely discontinuation of ciprofloxacin in our patient probably prevented tendon rupture and more significant nerve injury. Asymmetry of median nerve entrapments with more severe findings on the left in our case may be attributable to asymmetric tendinitis or possible pre-existing nerve entrapment aggravated by inflammation. Therefore, we should consider drug-induced tendinitis as a potential cause of musculoskeletal pain after institution of fluoroquinolone therapy. A recent report indicates that fluoroquinolones may also precipitate painful small fiber neuropathy expanding the spectrum of their toxicity.6 Early recognition of possible toxicity is crucial to stop the offending agent, avoid exercise, and hopefully reduce morbidity of fluoroquinolone-induced tendinitis.