Baxter's Nerve Entrapment

Baxter's nerve entrapment, also known as Baxter neuropathy, is plantar heel pain arising from compression of the inferior calcaneal nerve (Baxter nerve).

Anatomy

Baxter nerve (Nerve to abductor digiti quinti).

The inferior calcaneal nerve (Baxter nerve) is the first branch of the lateral plantar nerve, which is itself a branch of the tibial nerve. The nerve lies in between the abductor hallucis muscle and quadratus plantae.

The Gray's anatomy image and many other anatomy textbook images are incorrect. The Baxter nerve is quite posterior and lies very close to the calcaneus. It was named after Donald Baxter.

Aetiology

There are three entrapment points:

1. Deep to or adjacent to the fascial edge of a hypertrophied Abductor Hallucis muscle
2. Along the medial edge of the Quadratus Plantae
3. Adjacent to the medial calcaneal tuberosity.

Tarsal tunnel syndrome is a related condition but involves entrapment more proximally in the tarsal tunnel.

Risk Factors

Obesity, diabetes, muscle hypertrophy, hyperpronated foot, pes planus, plantar calcaneal spur, plantar fasciitis, spondyloarthritis.

Clinical Features

The clinical features may be similar to or coexist with plantar fasciitis. However there may be less morning pain, occasional altered sensation, and intrinsic muscle atrophy.

Differential Diagnosis

Differential Diagnosis of Heel Pain

• Plantar Fasciitis
• Fat Pad Contusion
• Calcaneal fractures (traumatic and stress)
• Inferior Calcaneal (Baxter) Nerve Entrapment
• Medial Calcaneal Nerve Entrapment
• Lateral Plantar Nerve Entrapment
• Medial Plantar Nerve Entrapment
• Tarsal Tunnel Syndrome
• Lumbar Radicular Pain
• Talar stress fracture
• Retrocalcaneal bursitis
• Spondyloarthritis
• Osteoid osteoma
• CRPS

Investigations

Coronal PD image showing fatty atrophy.

On MRI in the acute phase there is decreased T1 signal intensity and increased T2 signal intensity with fat saturation in the muscles innervated by the Baxter nerve. In the chronic phase there is fatty change of the abductor digiti minimi muscle, and occasionally the Flexor Digitorum Brevis and Quadratus Plantae.

Treatment

Baxter's nerve Sd. Procedure: corticosteroid injection & orthotics. Good result. @Dr_Ramon_Balius #MSKUltrasound pic.twitter.com/ED9RcmqJnz

— Ramon Balius (@Dr_Ramon_Balius) March 21, 2016