Baxter's Nerve Entrapment

Summary

Baxter's nerve entrapment refers to an entrapment of the calcaneal branch of the posterior tibial nerve (Baxter's nerve.) Baxter's entrapment results in plantar heel pain. Baxter's entrapment is typically unilateral but may be found bilaterally. Baxter's entrapment is most common in patients 25-50 years of age who are active in sports or in their occupation. Surgical release of the nerve is the preferred method of care.

Symptoms

• Numbness and/or pain of the plantar heel.

• Dull ache of the bottom and lateral aspects of the heel.

• No pain with initial weight bearing. Pain increases with the duration of time spent on the feet.

Description

Nerve entrapments occur throughout the body. Examples include carpal tunnel, tarsal tunnel, and nerve entrapments of the lumbar spine. Baxter's nerve entrapment refers to an entrapment of the calcaneal branch of the posterior tibial nerve (Baxter's nerve.) Baxter's nerve entrapment is a diagnosis that should be considered when treating heel pain. Although plantar fasciitis is a much more common cause of plantar heel pain, astute clinicians always will include Baxter's nerve entrapment in a complete clinical workup for heel pain.

Baxter's nerve has two functions: sensory and motor. Sensory function refers to sensations such as light touch, vibration, and the sensations of warmth and cold. Baxter's nerve entrapment will result in loss of sensation and pain in the plantar heel. Motor function is the ability to make a muscle contract. Baxter's nerve supplies motor innervation to the abductor digiti minimi muscle. The function of the abductor digiti minimi muscle is to abduct, or pull, the little toe away from the fourth toe. In extreme cases of Baxter's nerve entrapment, the motor function of the abductor digiti minimi muscle may be compromised. This test can be misleading in that many patients cannot abduct the little toe at all.

Another test used to diagnose Baxter's nerve entrapment is called a Phalen's maneuver. A Phalen's maneuver is performed as follows:  The foot is plantar-flexed and inverted. The porta pedis is palpated to elicit pain and paresthesia or numbness. A positive Phalen's maneuver results in pain in the region of Baxter's nerve. Phalen's maneuver has not been proven to be particularly reliable in clinical testing but often is described in the literature.

Causes and Contributing Factors

The biomechanical properties that may contribute to tarsal tunnel syndrome and Baxter's nerve entrapment are poorly-defined. Pronation, or flattening of the arch, may contribute to increased pressure within the porta pedis and subsequent pressure on the terminal branches of the posterior tibial nerve, including Baxter's nerve. The influence of a flat foot on Baxter's nerve entrapment has not been thoroughly studied.

Differential Diagnosis

The differential diagnosis for Baxter's nerve entrapment includes:

Arthritis of the foot and ankle
Calcaneal fracture
Foreign body injury
Heel spur
Plantar fasciitis
Plantar fat pad atrophy
Tarsal tunnel syndrome

Treatment

Conservative treatment of Baxter's nerve entrapment has historically proven to be unsuccessful. Conservative treatment may include NSAID's, steroid injections, ultrasound, and physical therapy. Prescription orthotics may be helpful to control contributing biomechanical issues such as pronation, theoretically relieving mechanical strain on Baxter's nerve.

Surgical release of the nerve, called external neurolysis, is the preferred method of care. The procedure is completed in a surgery center or hospital setting. External neurolysis of Baxter's nerve may be performed with a local anesthetic and sedation or with a general anesthetic. The goal is to identify the anatomical structure that contributes to physical irritation of Baxter's nerve. That structure is released, allowing Baxter's nerve to return to normal function. Recovery varies but cases do require a short period of non-weight-bearing on crutches. The long-term prognosis for external neurolysis for Baxter's nerve is good-to-excellent.

Other methods of treatment include cryosurgical neurolysis, chemical neurolysis, and radiofrequency ablation. Each of these methods uses cold, chemicals or heat to ablate or destroy Baxter's nerve. The literature does not discuss success rates of these methods compared to traditional external (surgical) neurolysis. When comparing the safety and efficacy of each of these methods of care you must remember that surgical neurolysis is a nerve-sparing surgery, whereas cryo, chemical, and radio-frequency ablation are nerve-destructive procedures. Therefore, patients considering one of these methods of treatment should discuss the pros and cons with their doctors prior to surgery.

Surgical external neurolysis of Baxter's nerve is a surgical release of one of the three branches of the posterior tibial nerve. Surgeons often perform a release of all three branches. When all three branches are released, this procedure is called a tarsal tunnel release. Tarsal tunnel release (external neurolysis of the posterior tibial nerve) is often used to treat tarsal tunnel syndrome. Doctors often refer to Baxter's nerve entrapment as a partial tarsal tunnel release, suggesting an isolated entrapment of the calcaneal branch of the posterior tibial nerve.

When Baxter's nerve entrapment is suspected and is found in conjunction with plantar fasciitis, surgical external neurolysis and a plantar fasciotomy may be performed at the same surgical setting.

References

References are pending.

Author(s) and date

This article was written by Myfootshop.com medical advisor Jeffrey A. Oster, DPM.

Competing Interests - None

Cite this article as: Oster, Jeffrey. Baxter's Nerve Entrapment. https://www.myfootshop.com/article/baxters-nerve-entrapment

Most recent article update - November 10, 2020.

  Baxter's Nerve Entapment by Myfootshop.com is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.

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