PERIPHERAL NERVE LESIONS

COMMON PERONEAL NERVE LESIONS

Presented byLouis law Mwadziwana

Background Common peroneal neuropathy is the most

common mononeuropathy encountered in the lower limb.

Weakness of ankle dorsiflexion and the resultant foot drop are common presentations.

It may also present with loss of sensation limited to the distribution of the deep or superficial peroneal nerve or its branches

ANATOMY OF THE COMMON PERONEAL NERVE

The common peroneal nerve is closely related to the head and neck of the fibular.

The nerve passes between the two heads of the peroneus longus where it is flattened and its constituent bundles are separated so that the nutrient vessels are exposed and are left unprotected between them.

It then curves round the neck of the fibula and then divide into its deep and superficial divisions.

Just before the nerve enters the peroneus longus it is held applied to bone and muscle attachments of the deep fascia. Not only is the nerve fixed at this point it is also angulated where it turns abruptly laterally from the gastrocnemius to pass between the two heads of the peroneus longus.

COURSE OF THE COMMON PERONEAL NERVE

COURSE OF THE COMMON PERONEAL NERVE

INJURY TO THE COMMON PERONEAL NERVE

The above anatomical features render the nerve and its nutrient vessels susceptible to damage in injuries about the knee.

The nerve is damaged through the following nerves

Traction• By posterior dislocation of the tibio-fibular joint

Compression • By pressure from an improperly applied plaster

Trauma during accidents• By fractures of the neck of the fibula

Ischemia• By compression ischaemia resulting from

crossing the legs or adopting an unusual posture, such as squatting

Signs and symptoms Cutaneous sensation is impaired over the

lateral aspect of the lower leg and ankle and dorsum of the foot.

Reduced dorsiflexion and eversion of the foot and of toe extension

• The patients will compensate by having a steppage gait.

N.B Inversion and plantar flexion are normal.

SIGNS AND SYMPTOMS CONTI

Progressive weakness of the peronei and tibialis anterior muscles which result in foot drop.

The peroneus longus , tibialis anterior and the extensor digitorum wastes.

N.B The paresis results in ankle

weakness and predispose to ankle sprains

Compression of the common peroneal nerve at the ankle

Deep peroneal nerve is rarely injured in the region of the ankle

Usually injury is due to a tight-fitting rim or strap from a shoe.

Pain in the region with minimal weakness and sensory disturbance involving only the web space between digits 1 and 2.

Physical exam reveals minimal abnormalities. Nerve conduction studies demonstrate a prolonged

distal motor latency.

MANAGEMENT Assistive and adaptive devices and

equipment.• Canes, crutches, or walkers may be used to

help prevent falling, normalize gait patterns, or unload a painful weight-bearing limb.

Electrical Stimulation.• Transcutaneous electrical nerve stimulation

(TENS) for the reduction or obliteration of pain.

Positioning. • Correct positioning of limb

Protective Devices and Equipment eg splints, orthoses

Cryotherapy, massage

REFERENCES Sunderland S, Nerves and nerve

injuries, 2nd edition, 1978, pages 974- 977

Mendell R et al, Diagnosis and management of peripheral nerve disorders, 2001, pages 621 – 625

Apley, System of orthopaedics and fractures, 5th edition, 1978, page 126

M. F. REINDERS, J. H. B. GEERTZEN and J. S. RIETMAN, Prosthetics and Orthotics International, 1996, 20, 197-198

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