Plantar heel pain of neural origin

Plantar heel pain is one of the most common conditions a clinical therapist encounters. Several conditions lead to heel pain like
• Plantar fasciitis
• Calcaneal fracture
• Rupture of plantar fascia
• Atrophy of  heel pad

Entrapment of tibial nerve and/or its branches may also cause heel pain. s. Although the contribution of nerve entrapment to plantar heel pain has been well documented in the literature, its pathophysiology, diagnosis and management are still controversial.

NERVE ENTRAPMENT SITES

The tibial nerve is the larger of the two major divisions of the sciatic nerve, and distally it divides into the following branches: medial calcaneal nerve (MCN), medial plantar nerve (MPN), lateral plantar nerve (LPN) (Gray et al., 2005) and the first branch of the LPN1.

Most authors have implicated the first branch of the LPN in this condition.2,3 . Patients with entrapment of the first branch of the LPN represent 15–20% of the patients with chronic plantar heel pain2,4.

Compression of the tibial nerve at the tarsal tunnel, a condition called tarsal tunnel syndrome (TTS), can also contribute to plantar heel pain.5,6
Entrapment of the MPN occurs where the fascial sling can bind the nerve beneath the talus and navicular bone (Schon, 1994; McCluskey and Webb, 1999)

CLINICAL REPRESENTATION

Pain: In patients with plantar heel pain of neural origin, pain is usually characterised as burning, sharp, shooting, shock-like, electric, localised or radiating either proximally or distally (Schon et al., 1993; Goecker and Banks, 2000), and occasionally as dull aching (Fredericson et al., 2001; May et al., 2002).

Post static diskynesia:

A common finding in patients with plantar heel pain of neural origin is pain when a patient first stands after periods of rest, a phenomenon called post-static dyskinesia (Oztuna et al., 2002; Jolly et al., 2005). Severe pain in the morning after rising from bed was found in a large number of patients with plantar heel pain of neural origin (Schon et al., 1993; Oztuna et al., 2002).

Pain of neural origin may decrease with sustained ambulation, whereas pain in plantar fasciitis is likely to increase (Jolly et al., 2005)
It should be noted, however, that post-static dyskinesia is not pathognomonic for plantar heel pain of neural origin. It also occurs frequently in patients with plantar fasciitis

Parasthasiae and neurological changes

Although sensory deficit is not common in entrapment of the first branch of the LPN (Pfeffer and Baxter, 1991), patients with TTS often complain of sensory disturbances (Schon and Baxter, 1990; Schepsis et al., 1991), such as tingling and/or numbness around the medial and plantar aspects of the heel.

DIAGNOSTIC TESTS

Palpation

Palpation over the abductor hallucis and/or on the medial calcaneal tuberosity reproduced symptoms in all patients (33) with suspected neurological plantar heel pain (Schon et al., 1993)
The diagnosis of entrapment of the first branch of the LPN should not be made without the presence of maximal tenderness over the nerve, although the entire heel and the proximal plantar fascia may also be tender (Baxter and Pfeffer, 1992; Goecker and Banks, 2000)

Diagnosis of entrapment of the anterior branch of the MCN can be substantiated by the following palpatory findings: (1) maximal tenderness over the medial anterior part of the heel fat pad and abductor hallucis, (2) distally radiating pain with pressure on the nerve and (3) only minimal tenderness over the plantar fascia origin (Henricson and Westlin, 1984)
With MPN entrapment, tenderness is typically located over the plantar aspect of the medial arch around the navicular tuberosity (Schon and Baxter, 1990).

Dorsiflexion-eversion and neurodynamic tests
Kinoshita et al. (2001) devised the dorsiflexion-eversion (DF/Eve) test for TTS. With this test, all metatarsophalangeal joints are passively extended while the ankle is held in dorsiflexion and eversion. This test reproduced or aggravated the symptoms in the majority of patients with TTS (36 out of 44 feet), but not in a healthy control group (Kinoshita et al., 2001).
In order to differentiate between structures, neurodynamic tests have been suggested for plantar heel pain (Butler, 2000, p. 414; Shacklock, 2005, pp. 232–235).
Plantar flexion-inversion test
Passive plantar flexion-inversion may reproduce or aggravate symptoms as the test increases pressure on the tibial nerve in the tarsal tunnel.

Tinel’s test : Tinel’s test consists of tapping along the course of a nerve. The test is considered positive when it results in tingling along the nerve distribution. While Tinel’s test is often positive in TTS (Schon and Baxter, 1990; Kinoshita et al., 2001), and can be positive in MPN entrapment (Schon and Baxter, 1990), the test is usually negative in entrapment of the first branch of the LPN (Fredericson et al., 2001). Baxter and Pfeffer (1992) found a positive Tinel’s test in only 12 of 69 heels (17%) with entrapment of the first branch of the LPN

Electro diagnostic tests

• Electromyography and nerve conduction studies
  • Quantitative sensory testing
  • High-resolution ultrasound
  Differential diagnosis and treatment will be continues in next part.
  
  
  
  Referances:
  1. Przylucki H, Jones CL. Entrapment neuropathy of muscle branch of lateral plantar nerve: a cause of heel pain. Journal of the American Podiatry Association 1981;71(3):119–24

2. Baxter DE, Pfeffer GB, Thigpen M. Chronic heel pain: treatment rationale. Orthopedic Clinics of North America 1989;20(4):563–9
3. Watson TS, Anderson RB, Davis WH, Kiebzak GM. Distal tarsal tunnel release with partial plantar fasciotomy for chronic heel pain: an outcome analysis. Foot and Ankle International 2002;23(6): 530–7
4. Pfeffer GB. Plantar heel pain. Instructional Course Lectures 2001;50: 521–31
5. Kinoshita M, Okuda R, Morikawa J, Jotoku T, Abe M. The dorsiflexion-eversion test for diagnosis of tarsal tunnel syndrome. The Journal of Bone and Joint Surgery—American Volume 2001;83-A(12):1835–9.
6. Lau JT, Stavrou P. Posterior tibial nerve—primary. Foot and Ankle Clinics 2004;9(2):271–85.
   7. Oztuna V, Ozge A, Eskandari MM, Colak M, Golpinar A, Kuyurtar F. Nerve entrapment in painful heel syndrome. Foot and Ankle International 2002;23(3):208–11.
7. Jolly GP, Zgonis T, Hendrix CL. Neurogenic heel pain. Clinics in Podiatric Medicine and Surgery 2005;22(1):101–13.
8. Schon LC, Glennon TP, Baxter DE. Heel pain syndrome: electrodiagnostic support for nerve entrapment. Foot and Ankle 1993; 14(3):129–35
   10. Goecker RM, Banks AS. Analysis of release of the first branch of the lateral plantar nerve. Journal of the American Podiatric Medical Association 2000;90(6):281–6
9. Henricson AS, Westlin NE. Chronic calcaneal pain in athletes: entrapment of the calcaneal nerve? The American Journal of Sports Medicine 1984;12(2):152–4.

Main source of information  is A review of plantar heel pain of neural origin:

Differential diagnosis and management Ali M. Alshami, Tina Souvlis, Michel W. Coppieters