F-ratio, a surrogate marker of carpal tunnel syndrome

ABSTRACT

To explore the correlation of F-ratio and F-wave minimal latency [FWML] in carpal tunnel syndrome [CTS]. This retrospective study was conducted from January 2006 to January 2007 at the clinical physiology lab, King Abdul-Aziz University Hospital, Riyadh, Saudi Arabia. Motor and sensory nerve conduction studies, FMW latencies of median and ulnar nerves, and F-ratio were carried out in 54 CTS patients and 30 controls. Out of 54 CTS patients, there were 14 were males [26%], and 40 females [74%], CTS was bilateral in 32 [59%], and unilateral in 22 [41%] patients. Fifty-one patients [94.4%] had involvement of the right hand, 28 patients [51.8%] had dyslipidemia and 20 patients [37%] had hypertension. The FWML [ms] in the right median nerve was 25.46 +/- 2.2, and 25.79 +/- 1.7 in the right ulnar nerve in the control group [p = 0.5224], while it was 29.1 +/- 3.35 in the right median nerve and 26.46 +/- 4.35 in the right ulnar nerve in patients with CTS [p = 0.0008]. A similar statistically significant increase in the median nerve latency was observed in the left hand. A statistically significant reduction in the F-ratio was found consistently in all patients with CTS in both the hands [p = 0.0001]. The present study reveals prolongation of FWML in the median nerve, and a statistically significant reduction of F-ratio in all CTS patients. A significant inverse correlation was found between FWML and F-ratio in CTS patients. Both FWML and F-ratio support the diagnosis of CTS