15018752330
发表时间:2015-12-09 浏览次数:955次
Introduction
The tibial nerve lies between the superficial and the deep muscles of
the posterior compartment of the leg. It is well-protected from direct
trauma due to this thick cover of muscles. In the lowermost part of the
leg and ankle, the nerve is relatively superficial but is guarded
anteriorly by the posterior surface of the medial malleolus,
superficially by the flexor retinaculum and posteriorly by the
Achilles's tendon. This protected location makes isolated injury to the
tibial nerve is very uncommon. Even in cases of open fractures and
associated vascular injuries of the lower extremity complete transaction
of the tibial nerve is rare. [1] Injuries to the sciatic and common peroneal nerves are more common due to their vulnerable position. [2],[3]
Most of the available literature on peripheral nerve injuries in the
lower extremity has documented the results and the treatment options for
peroneal and sciatic nerve injuries.
Other common causes of lower limb neuropathy are diabetic neuropathy [4] and compression neuropathies. [5]
Tibial nerve involvement is more common in these chronic conditions.
The common end result of the tibial nerve injury or neuropathy around
the ankle is loss of sensations of the plantar foot, vasomotor changes
due to lack of auto-regulation, subsequently leading to callosities and
recurrent ulcerations and paralysis of the intrinsic muscles of foot
leading to toe deformities.
We report a very unusual presentation
of isolated posterior tibial nerve injury following a road traffic
accident. Our search failed to reveal any similar case reported in the
English literature.
Case report
A written consent was obtained from the patient and her attendants. A 15-year-old girl sustained injury to her left leg following road traffic accident. Though the exact mechanism of injury could not be elicited, she remembered falling down from her two-wheeler after it collided with a car. She sustained a small puncture wound over the lower posterior leg and was referred to our hospital after the first aid at a local hospital. On examination, she had a penetrating wound over the Achilles tendon with some soft tissue mass avulsed through the tear in the Achilles tendon [Figure 1]. The avulsed soft tissue was tender on touch. She had a lack of sensation over the plantar foot, and the foot was warm. The skin texture and turgor were found to be normal. With a provisional diagnosis of tibial nerve injury, the wound was explored. The soft tissue avulsed and protruding through the tendon was the tibial nerve [Figure 2a]. While the posterior tibial vessels and the flexor tendons were intact.
Discussion
Well recognized and documented examples of nerve injuries in the lower
limb are the sciatic nerve injury at the hip during posterior fracture
dislocations, iatrogenic injuries during injections and peroneal nerve
injury following fracture of the neck of the fibula. [2],[3],[6] Injury to the posterior tibial nerve is, fortunately, very rare. [1],[7],[8]
Though the mechanism of injury is not exactly known in the presented
case, some sharp object must have pierced the Achilles tendon to reach
the nerve and due to change of the direction as the patient fell down it
must have got entangled around the nerve, ultimately avulsing it.
The
actual site of nerve injury was much higher than perceived site of
injury, possibly a relatively fixed point like a muscular branch and is
difficult to predict. [9]
This can be considered analogues to brachial plexus injuries where the
forces involved usually avulse the nerves from a relatively fixed point.
This may also help in explaining the fact that the upper roots are
either avulsed or ruptured (as they have few branches in the neck), but
the lower roots are almost always avulsed in a global brachial plexus
injury. Nerves are much tougher structures and coniderable force is
required to avulse a nerve completely. In the presented case the nerve
was completely avulsed, indicating the force involved.
Nerve
repair or reconstruction should be carried out as early as possible
after the injury. Children have better potential for nerve recovery and
primary repair should be attempted as and when possible. For grossly
contaminated wounds, injuries with extensive crushing and cases where it
is difficult to know the exact extent of injury, delayed primary repair
is recommended. [10]
Radical debridement up to vital axons and nerve grafting was the only
chance for recovery. In our case the avulsion of the nerve and the
amount of damage observed on table warranted the waiting period of 3
weeks before definitive reconstruction.
After diagnosing the
injury, there were two possible ways of reconstruction of the
defect/loss. One option was a primary nerve transfer [11],[12] and the other was that of nerve reconstruction with nerve grafts. [13]
The number of axons in the donors locally available (superficial
peroneal and sural) are limited, and also they have only sensory fibers.
On the contrary, the tibial nerve has sensory and motor fibers for the
intrinsic muscles of the foot. Nerve grafting in children has better
success rate than in adults. [14]
We harvested nerve grafts from contra-lateral sural nerve to keep the
option of nerve transfer open if required in the future. She recovered
sensations completely in around one and half years after the
reconstruction, and her age was the most important factor in her
recovery.
Injury to the tibial nerve in the lower leg leads to
the loss of sensation at the plantar foot. Though the function of the
leg muscles was preserved in this case, the insensate foot can be
equally disabling due to loss of position sense and predisposition to
injuries to the plantar foot. Atrophy and vasomotor changes complicate
the injury. Furthermore, the paralysis of the intrinsic muscles of the
foot leads to deformities over a period.
These patients need to
protect their feet from injuries till they regain the protective
sensations. Importance of the care of the insensate part has to be
stressed during each follow-up visit. At the initial visit, the
exploration of the wound for debridement and assessment of injury and
the middle third of the leg for assessing the status of the proximal
stump were necessary. We feel that these could have been possible
through two separate incisions to decrease scarring. The nerve
reconstruction also would have been possible at a later date through the
same scars by tunneling the nerve grafts subcutaneously. In this case
as the initial scar was present we went through the same scar for
reconstruction.
In a selected and cooperative patient, nerve grafting in lower extremity can result in rewarding results.
References
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2.Simon JP, Van Delm I, Fabry G. Sciatic nerve palsy following hip surgery. Acta Orthop Belg 1993;59:156-62.
3.Ferraresi S, Garozzo D, Buffatti P. Common peroneal nerve injuries: results with one-stage nerve repair and tendon transfer. Neurosurg Rev 2003;26:175-9.
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10.Songcharoen P. Neurotization in the treatment of brachial plexus injury. In: Omer GE, Spinner M, Van Beek AL, editors. Management of Peripheral Nerve Problems. Philadelphia: W.B. Saunders; 1998. p. 459-64.
11.Koshima I, Nanba Y, Tsutsui T, Takahashi Y. Deep peroneal nerve transfer for established plantar sensory loss. J Reconstr Microsurg 2003;19:451-4.
12.Gordon L, Buncke HJ. Restoration of sensation to the sole of the foot by nerve transfer. A case report. J Bone Joint Surg Am 1981;63:828-30.
13.Nunley JA, Gabel GT. Tibial nerve grafting for restoration of plantar sensation. Foot Ankle 1993;14:489-92.
14.Senes FM, Campus R, Becchetti F, Catena N. Lower limb nerve injuries in children. Microsurgery 2007;27:32-6.