What is involved?
Posterior Tibial Nerve
Location
Posterior Tibial nerve entrapment at the Tarsal Tunnel in the foot at the level of the medial malleolus
Common symptoms
- Foot, Ankle, Sole pain/burning and aching
- Worse at night
- Occasional numbness/tingling sole of foot
- No muscle weakness
- Usually unilateral
- Difficulty walking because of pain and discomfort with shoes
- Positive Tinel (tingling upon tapping nerve) sign behind the medial malleolus
Onset
- May be Sudden in trauma, injury
- Usually Gradual, weeks, months
Risk factors
- No gender preference
- Diabetes or family history of Diabetes, Alcoholism or other occupational or nutritional causes of Neuropathies, HIV infection
- Usually post-traumatic
- Can be aggravated with joint inflammation from tenosynovitis, phlebitis
Exam
- Very positive and tender Tinel (tingling upon tapping nerve) sign behind the medial malleolus
- Usually ankle swelling, tenderness
- No weakness or atrophy
- May have decreased sensation over the sole of the foot
- Patient quite uncomfortable with standing, walking
Localization
The Posterior Tibial nerve inside the Tarsal Tunnel affecting both Medial and Lateral Plantar nerves of the foot
EMG
- Prolonged Posterior Tibial distal latency to the Abductor Hallucis or Abductor Digiti Quinti Pedis
- May be accompanied by low motor amplitude or absent responses in either of these muscles
- Medial and/or Lateral plantar sensory action potentials may be affected early on with prolonged latency, slowed velocity and decreased amplitude
- Sensory Action potentials unobtainable in advanced cases
- Needle exam of Abductor Hallucis and/or Abductor Digiti Quinti Pedis may show denervation, active and/or chronic
- Check non-Posterior Tibial muscles (Extensor Digitorum Brevis) or Posterior Tibial muscles above the Tarsal
Tunnel (Posterior Tibialis) are spared and Lumbo-Sacral paraspinals are intact to ensure this is not an S1 root lesion
Recommendations
- Symptomatic treatment by relieving cause and treating local trauma
- Foot brace and arch support
- Anti inflammatory medications
- Surgery in advanced cases
- In complicated and post-operative ankle injuries, surgery may actually worsen the symptoms
What else could it be?
- Could be ankle joint pain without involvement of the Posterior Tibial nerve
- If bilateral, suspect Diabetes, Small Fiber Neuropathy (symptoms not just limited to the foot), but more importantly, bilateral S1 root lesions