Painful legs and moving toes following a traumatic medial plantar nerve injury

Authors

  • Murat Zinnuroglu MD,

    Corresponding author
    1. Department of Physical Medicine and Rehabilitation, Gazi University, Ankara, Turkey
    2. Department of Physical Medicine and Rehabilitation, Bursa Military Hospital, Bursa, Turkey
    • Department of Physical Medicine and Rehabilitation, Gazi University, Ankara, Turkey
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  • Tufan Ozkayran MD

    1. Department of Neurology, Bursa Military Hospital, Bursa, Turkey
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  • Potential conflict of interest: Nothing to report.

Painful legs and moving toes (PLMT) is a rare syndrome, which is characterized by involuntary movements of the toes and pain in the legs.1 Peripheral nerve injury results in sensory and motor loss in relation to the extend of the axonal degeneration distal to the site of injury and subsequent denervation and reorganization of peripheral and central connections, which lead to significant alterations and in peripheral connectivity and reflex organization.2

A 40-year-old male patient presented with shaking of the right toes. Patient had a partial rupture of the right Achilles tendon 3 years ago following a direct blunt trauma to the medial and posterior side of the ankle and treated with a short leg cast for 3 months. He noticed the shaking of the right toes after removing the cast. He had dysesthesia and pain in the sole of the right foot extending from the heel to the toes after the trauma. Sensory symptoms gradually improved and disappeared within 2 months. He was diagnosed with dystonia and treated with baclophen. There was no sign of improvement.

Upon neurological examination, there was mild hypoesthesia in the right medial plantar nerve distribution. A rhythmic, continuous, and complex flexion/extension, adduction/abduction, fanning, and clawing of the right toes with slow frequency was noted. Involuntary movements were present at rest and disappeared during sleep and when the foot was touched by the examiner (Video 1).

Nerve conduction studies of bilateral peroneal, posterior tibial, lateral plantar, sural, and left medial plantar nerves were normal. Sensory nerve conduction study of the right medial plantar nerve revealed decreased amplitude of the sensory nerve action potentials (decreased by 65.2% when compared with the right side;3 Table 1). Surface EMGs were recorded from flexor digitorum brevis muscle. Movements had a synchronous pattern with a frequency of 3 Hz, burst duration of 190–210 m/sec, and mean amplitude of 236 μV (Fig. 1).

Figure 1.

Surface EMG record from the flexor digitorum brevis muscle.

Table 1. The results of medial and lateral plantar sensory nerve conduction studies
 Medial plantar nerveLateral plantar nerve
NCV (m/sec) (NL: 28.0)Amp (μV) (NL:2.8)NCV (μV) (m/sec) (NL:22.9)Amp (μV) (NL: 1.0)
  1. NCV, nerve conduction velocity; m/sec, meter per second; NL, normal limit; Amp, amplitude; μV, microvolt.

Right38.44.636.43.1
Left37.61.635.22.8

Patient was commenced on Propranolol 20 mg daily and was increased up to 40 mg. Movements disappeared completely by 40 mg propranolol. There was no sign of involuntary activity in the control examination at the first month (Video 2).

In this case, there are two possibilities which may injure the medial plantar nerve. One of them is the direct blunt trauma and the latter is prolonged compression by the cast. We believe that the time interval of 3 months until the removal of the cast was sufficient for the recovery of mild and partial affection of a peripheral nerve. Therefore, we think that the lesion was probably related with the direct trauma or compression due to the haemorrhagia following the trauma.

A few cases were reported, suggesting a relationship between focal peripheral nerve lesions and moving toes, which showed myokymic discharges on EMG examination.4, 5 We think that this may also be related with the increased excitability and impaired excitation of the motor neuron. It was demonstrated that peripheral nerve injuries and subsequent reinnervation result in alterations of the central connectivity and the peripheral circuitry.2 Another case with tarsal tunnel syndrome was reported, which also showed myokymic discharges and an absent lateral plantar nerve response on electrophysiological examination.4 The different feature of our case was the absence of the pain after the first few months. Additionally, treatment options are relatively limited in PLMT and medications such as gabapentin, which also have analgesic effects, are usually preferred. We think that propranolol may be used especially in cases without pain.

It was shown that the effects of the peripheral nerve lesion and subsequent reinnervation are far reaching and may lead to impaired excitability in the spinal cord.2, 6 Also, cortical hand representations are highly abnormal following reinnervation, where larger and often multiply represented receptive fields have a disordered and fractured somatotopic arrangement.7

In conclusion, peripheral nerve injuries may rarely present with involuntary movements, and this may be related with the abnormal reorganization of the reinnervated axons and the abnormal central connectivity. The incidence of the movement disorders and the underlying pathology following the peripheral nerve injuries should be further investigated. Propranolol may be a choice for the treatment.

Legends to the Video

Segment 1. Complex flexion/extension, abduction/adduction movements in the toes before the treatment.

Segment 2. No sign of involuntary movements at the first month of the treatment with propranolol.

Author Roles:

Zinnuroglu M: Patient assessment and writing of the first draft and review and critique of the manuscript; Ozkayran T: Writing of the first draft and review and critique of the manuscript.

Murat Zinnuroglu MD* †, Tufan Ozkayran MD‡, * Department of Physical Medicine and Rehabilitation, Gazi University, Ankara, Turkey, † Department of Physical Medicine and Rehabilitation, Bursa Military Hospital, Bursa, Turkey, ‡ Department of Neurology, Bursa Military Hospital, Bursa, Turkey.

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