Plantar fasciitis is a common cause of pain under the heel and Baxter’s neuritis is a less common cause, but they often mimic each other, so clinically it is extremely important to differentiate them from each other. Plantar fasciitis is an overuse and inflammatory condition of the plantar fascia. Baxter’s neuritis is an entrapment neuropathy of the nerve on the medial plantar area of the heel.
Some of the clinical characteristics to look for as to how plantar fasciitis and Baxter’s neuritis differ are:
- Plantar fasciitis is characterized by the more severe first step pain (post-static dyskinesia) whereas Baxter’s neuritis tends to be more painful later in the day.
- In Baxter’s neuritis, the maximum pain is usually where the affected nerve is compressed between the abductor hallucis muscle and the quadratus plantae muscle, more over plantar medial aspect of heel rather than just the plantar area where insertional plantar fasciitis is most painful.
- The pain in Baxter’s neuritis can sometimes radiate forward due to the involvement of the nerve. There may also be some numbness in the medial plantar arch area. At times, there might be a burning sensation along the lateral side of the foot.
- In Baxter’s neuritis, it may be possible to elicit neuritic pain when you palpate the nerve in area of medial plantar heel along abductor hallucis muscle or the plantar fascia.
- Those with Baxter’s neuritis may not be able to abduct their lessor digits as the branch to abductor digiti quinti brevis muscle is commonly affected. Normally this is difficult for many people to perform anyway, so compare it to asymptomatic side.
- Plantarflexion and inversion of the foot may produce neural symptoms in those with Baxter’s neuritis.
- Imaging with MRI or ultrasound will tend to show the tissue damage in plantar fasciitis and may show a thickening of Baxter’s nerve.