Bicycle Seat Neuropathy

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A wide frequency range has been reported for bicycle seat neuropathy, but it is believed to be underreported. The medical literature contains several case reports of reversible neuropathy[5, 9] and several retrospective studies surveying participants in long-distance cycling races and tours.[8, 11, 12]

Andersen and Bovim surveyed 260 cyclists participating in a long-distance bike tour that was 335.54 miles (540 km) in length.[8] Of responding males, 35 (22%) reported symptoms of either numbness or pain in the pudendal area. Thirty-three (21%) males reported penile numbness, with 10 (6%) male cyclists reporting symptoms that lasted longer than 1 week. In addition, 21 males (13%) reported symptoms of impotence, 11 of whom experienced symptoms for longer than 1 week, and 3 of whom reported impotence lasting longer than 1 month.[8]

Kuland and Brubaker reported that during the 1976 Bikecentennial tour, there was a 7% incidence of pudendal and/or penile numbness, but this study only surveyed 89 of 1200 participating cyclists.[11]

Weiss studied symptoms of cyclists participating in a 500-mile (804.97 km) bicycle tour.[12] Of the participating cyclists, 45% reported at least mild and transient perineal numbness; 10% reported the symptoms as severe, and 2% of the cyclists had to temporarily stop riding. Perineal numbness has also been documented in women cyclists. LaSalle et al surveyed 282 female members of a Dallas cycling club.[13] In this group, 34% of the women reported perineal numbness.

Potter et al assessed the differences between men and women with regard to bicycle saddle pressure distribution during seated cycling.[14] The authors noted that there were significant differences between the sexes in saddle loading, and these differences were especially relevant with regard to the position of the bicycle handlebar positions. In particular, the drops hand position shifted the rider's weight, such that more weight was supported on the anterior pelvic structures.[14]

The cause of bicycle seat neuropathy has been attributed to several different ischemic and neurologic events. Amarenco et al and Oberpenning et al hypothesized that compression of the pudendal nerve as it passes through the Alcock canal causes the condition.[9, 15] 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.[9] 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.[12, 16] Weiss also theorized that the genital branch of the genital-femoral nerve could be involved in cases in which scrotal paresthesia is reported.[12]

Bicycle seat design (eg, shape) may be the major extrinsic factor for the development of bicycle seat neuropathy.[1, 4, 6, 17, 18, 19, 20, 21] Results of computer modeling reported by Spears et al showed that wider bicycle seats that support the ischial tuberosities decrease pressure on the perineal area.[19] Other studies have also demonstrated the effect bicycle seat design has on penile blood flow[20] and penile oxygen pressure.[21]

The prognosis and recovery from bicycle seat neuropathy is very good. However, the rate of recovery is variable and may be influenced by the amount of time the athlete previously spent cycling.

Complications

Complications are variable and appear to be transient based upon the literature review. Cases of bicycle seat neuropathy and its resulting symptoms, such as impotence, resolve over time once the pressure is relieved from the perineal region. Case reports reveal that some cases can take more than 1 month to resolve.[1, 5, 8, 9]

Educate patients about the causes of the neuropathy, about the importance of a proper bike fit, and about the need for changes in seating position.

For excellent patient education resources, visit eMedicineHealth's Men's Health Center and First Aid and Injuries Center. Also, see eMedicineHealth's patient education articles, Impotence/Erectile Dysfunction, Erectile Dysfunction FAQs, and Bicycle Safety.

A recreational or elite cyclist who complains of numbness or impotence after cycling is the typical presentation of bicycle seat neuropathy.[22, 23, 24, 25] The amount of time the athlete spent cycling before the onset of symptoms is variable; however, studies have focused upon longer distance, multiday rides. Use of a stationary bicycle has also been reported as a cause of bicycle seat neuropathy.

Ask pertinent questions while obtaining the history to attempt to elicit other causes of neuropathy or impotence, such as a history of diabetes; metabolic disorders; endocrine or vascular disease; perineal trauma; or testicular, prostate, or intra-abdominal cancers.

Ask questions regarding the timing, duration, and location of the symptoms. Also inquire about the extent of the symptoms; some cyclists report mild numbness and some report more severe symptoms such as impotence or urinary incontinence.

Ask about the length and duration of rides. Also ask about any recent increase in training volume or any changes in bicycles, bicycle setup, or bicycle position.

The physical examination should focus on the urogenital and neurologic systems. A rectal examination may be indicated. The focus of the examination should be to exclude other diagnoses that may require different treatment and management.

The urogenital examination should include examination and palpation of the penis, testicles (in males), and perineal area.

Neurologic examination should include testing of motor and sensory function of the same regions.

Laboratory tests are not indicated in the diagnosis of bicycle seat neuropathy. Specific laboratory tests should be ordered based on the clinical consideration for other disorders with similar symptoms of paresthesias or impotence. Tests may include vitamin B-12 and folate levels, a thyrotropin value, a fasting blood glucose level, and a cholesterol panel.

Doppler ultrasound of the vascular structures may be indicated.

Consider obtaining plain radiographs or a computed tomography (CT) scan of the abdomen and/or pelvis to rule out pelvic fracture if the patient's history indicates trauma.

Rehabilitation program

Recreational therapy

Recreational therapy should include evaluation of the rider's position on the bicycle and could include changing the seat height and tilt position.

Medical issues/complications

Medical issues and complications include continued injury or insult to the area, resulting in continuation of the neuropathy and long-term sequelae such as impotence. Reevaluate the patient after making changes to the bicycle or riding style or after decreasing the training volume to ensure that improvement in symptoms is occurring. Continued symptoms despite changes in the bicycle seat position and training volume may indicate a different source of the symptoms and should warrant reevaluation by the physician.

Consultations

Possible consultations include specialists in urology and neurology, based upon the patient's clinical presentation.

Other treatment

The mainstay of treatment of bicycle seat neuropathy is the adjustment of the bike seat and bike position, such as tilting the nose of the seat down or lowering the seat height to relieve pressure off the perineum. Other recommendations include having the rider change the style of riding (eg, change positions more frequently or stop riding as frequently).

Newer bicycle seats with a split nose or a center cutout may also help to reduce the prevalence of neuropathy by limiting compression on the perineal area (see the image below). A study by Lowe et al compared pressure measurements in the perineal area of cyclists on these different bicycle seats and found that some of the newer seats reduced perineal pressure by approximately 50%.[17]

Another study by Parthiban et al used Doppler ultrasound to identify perineal artery occlusion forces and to facilitate force sensor placement in order to measure the occlusive force exerted over the perineal arteries in a variety of bicycle seat designs. The study found that that the “no-nose” bicycle seat design is associated with significantly less instances of perineal arterial occlusive pressure during bicycling. However, the study also added that all seats that were studied achieved occlusive pressures for a minimum 41% of riding time.[26]

The results of a systematic review and meta-analysis by Litwinowicz et al support the use of a no-nose bicycle seat to decrease internal perineal compression in men. The researchers also found indirect evidence that standing on the pedals every 10 minutes can reduce the impact of cycling on the perineum.[27]

Return to play is based upon resolution of the athlete's symptoms. The cyclist should be cautioned to change his or her 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 [tri-bars]). 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 may also be helpful; elevation of the nose of the bicycle seat may worsen the condition, as more pressure is placed upon the Alcock canal and the pudendal nerve.

Prevention of bicycle seat neuropathy includes riding a bike that is properly fit by a trained professional, as well as changing positions frequently on the bike seat or standing intermittently to relieve perineal pressure. Additionally, newer designs in bicycle seats allow for the reduction of perineal pressure by providing a bicycle seat with the middle portion cut away.