High frequency ultrasonography in the management of carpal tunnel syndrome

ABSTRACT

To evaluate the diagnostic usefulness of high frequency ultrasound in the management of Carpal Tunnel Syndrome among patients suspected of having this syndrome. Twenty- six patients [22 women and 4 men] with a mean age of 48.5 years [range 27-70 years] suspected of having carpal tunnel syndrome were examined by high frequency ultrasound at the middle of the carpal tunnel within two weeks after electro diagnostic testing and included in the study. Fourteen patients had bilateral symptoms and 12 patients had unilateral symptoms [total 40 symptomatic hands] [Twenty-six patients [five men and 21 women, mean age 38 years, range 23 71 years]]. The cross- sectional area of the median nerve was measured at the carpal tunnel. The hook of the hamate, the pisiform bone and the flexor retinaculum were used as landmarks to margins of carpal tunnel. The cut- off point for the cross -sectional area was chosen to be 9.7milimetre squared. Sensitivity and specificity of ultrasound were determined on the basis of the final diagnosis derived from the patient's history and electromyographic studies results which was used as the gold standard. High-frequency ultrasound had a sensitivity of 94% and a specificity of 75%. The increased cross-sectional area of the median nerve was the most consistent finding in 80% [32 740] of patients, while thickening of the flexor retinaculum was found in 25% [10/40] and tenosynovitis of the flexor tendon in 22% [9/40]. Flattening of the median nerve was present in l0% [4/40] while ganglion and swelling of the median nerve were present in 7.5% [3/40] respectively. High- frequency ultra- sonography is an effective method for the diagnosis of and may be preferred as the first step in the assessment of carpal tunnel. Furthermore, ultrasound may also provide information about the cause of carpal tunnel syndrome and thus helping planning treatment and follow-up of patients