Bicycle seat neuropathy is one of the more common injuries reported by cyclists (Weiss, 1994). The injuries and symptoms are due to the cyclist supporting his or her body weight on a narrow seat and are believed to be related to either vascular or neurologic injury to the pudendal nerve (Oberpenning, 1994).
SPORT SPECIFIC BIOMECHANICS
The cause of bicycle seat neuropathy has been attributed to several different ischemic events. Amarenco and Oberpenning hypothesized that compression of the pudendal nerve as it passes through the Alcock canal causes the condition. The Alcock canal is enclosed laterally by the ischial bone and medially by the fascial layer of the obturator internus muscle. The pudendal nerve exits the canal ventrally, below the symphysis pubis, and innervates the genital and perineal regions.
Oberpenning et al postulated that long-distance cycling results in the indirect transmission of pressure onto the perineal nerve within the Alcock canal. Weiss and Bond separately proposed that bicycle seat neuropathy is due to temporary and transient ischemic injury to the dorsal branch of the pudendal nerve secondary to compression of the nerve between the bicycle seat and the symphysis pubis. Weiss also theorized that the genital branch of the genital-femoral nerve could be involved in cases in which scrotal paresthesia is reported.
Bicycle seat design (eg, shape) may be the major extrinsic factor for the development of bicycle seat neuropathy. Results of computer modelling reported by Spears et al in 2003 have shown that wider bicycle seats that support the ischial tuberosities decrease pressure on the perineal area
A recreational or elite cyclist who complains of numbness or impotence after cycling is the typical presentation of bicycle seat neuropathy. The amount of time spent cycling before the onset of symptoms is variable; however, studies have focused upon longer distance, multiday rides. Use of a stationary bicycle also has been reported as a cause of bicycle seat neuropathy.
RETURN TO PLAY
Return to play is based upon resolution of symptoms. The cyclist should be cautioned to change position on the bike (eg, ride with hands on the top of the handlebars vs having hands down in the drops or riding with aerobars). Also encourage the patient to stand up intermittently to relieve pressure or to stop cycling temporarily until the symptoms resolve. Changing the type and shape of bicycle seat used also may be helpful.
Author: John M Martinez, MD,