Causes and clinical presentation of common fibular nerve lesion
One of the frequent indications for conservative and surgical treatment is common fibular nerve neuropathy. A typical level of its lesion is localized distal to the fibular head. In this area, the nerve trunk passes through an anatomically narrow space between the bone structure and the fibrous edge of the fibularis longus muscle.
Several key mechanisms and etiological factors of compression are distinguished:
- Acute entrapment: occurs against the background of sharp plantarflexion combined with foot supination.
- Chronic trauma: develops as a direct consequence of repeated sprains.
- Positional compression: is associated with prolonged stays in a disadvantageously fixed position. This includes working while squatting (for example, in low tunnels, during floor scraping, or agricultural work), as well as the habit of crossing legs.
- Iatrogenic or external compression: is often caused by prolonged tissue compression from a plaster cast.
The clinical picture of this condition includes three groups of disorders. First, there are motor disorders, manifested by paralysis of the foot and toe extensor muscles. Second, sensory disorders, characterized by analgesia along the outer surface of the lower half of the leg, as well as on the dorsal surface of the foot and digits I–IV. Third, with a prolonged course of the pathology, trophic disorders join in, leading to pronounced atrophy of the anterior and lateral muscle groups of the leg.
Tibial nerve neuropathy and other lesions
Compression of the tibial nerve occurs within the osteofibrous tarsal tunnel (tarsal tunnel syndrome). To understand the pathogenesis, it is important to know the anatomy of this canal:
- Anteriorly, it is bounded by the medial malleolus.
- Laterally, the calcaneus is located.
- Medially, the canal is closed by the fibrous band of the flexor retinaculum, which is tightly stretched between the medial malleolus and the calcaneus.
Etiologically, compression of the nerve trunk at this level is most often provoked by edema of the canal contents or a hematoma resulting from an ankle joint injury. The leading clinical symptom is pain in the plantar surface of the feet and toes, occurring during walking and resembling "intermittent claudication". In addition, predominantly nocturnal pain is extremely characteristic of tarsal tunnel syndrome.
Sciatic nerve neuropathy (due to piriformis syndrome) is also encountered in clinical practice. In the objective status of such patients, a decrease in the Achilles reflex is determined, and subjectively, pain is noted in the area of the infrapiriform foramen, which often radiates strictly along the course of the sciatic nerve.
Conservative and surgical treatment (neurolysis)
The management tactics for patients with compression neuropathies depend on the severity of symptoms and include both conservative and radical methods.
Conservative treatment The most adequate and frequently used method is performing glucocorticoid injections (with the addition of procaine or in pure form) directly into the anatomical canal or into the tissues immediately surrounding the affected nerve. Drug dosage directly depends on the type and localization of the lesion. For example, in carpal tunnel syndrome, the standard is a single administration of 50 mg of hydrocortisone, with a possible repetition of the procedure after 6–7 days.
Surgical treatment Surgical intervention is considered a radical method. Relative indications for surgery include the failure of long-term glucocorticoid therapy or the presence of strict contraindications to their injection.
Absolute indications include:
- Severe deficits in both motor and sensory functions.
- Rapid progression of neurological symptoms with progressive loss of nerve functions.
The essence of the operation itself is relatively simple. The intervention consists of careful dissection of the compressing tissues (neurolysis). This allows for the creation of optimal spatial conditions for the nerve trunk and completely avoids its further trauma. In the postoperative period, for the rapid restoration of functions, the patient is prescribed the full available arsenal of physiotherapeutic agents, and modern neurostimulators are also used.
Briefly: answers to topical questions
Which specific muscles are paralyzed in common fibular nerve neuropathy?
In common fibular nerve neuropathy, motor disorders develop in the form of paralysis of the foot and toe extensors. Also, with a prolonged course of the pathology, atrophy of the anterior and lateral muscle groups of the leg develops.
What clinical symptoms manifest piriformis syndrome?
Piriformis syndrome manifests as pain in the area of the infrapiriform foramen, which often radiates along the course of the sciatic nerve. In the objective status of patients, a characteristic decrease in the Achilles reflex is determined.
What types of nerve suture exist depending on the timing of execution?
Depending on the timing of execution and the type of injury, a primary nerve suture is distinguished, which is performed during the primary surgical debridement of the wound when the injury is no more than 12 hours old, as well as a secondary nerve suture, used in all other cases.
What is the technique for applying an epineural nerve suture?
The technique for applying an epineural nerve suture is performed strictly after preliminary surgical debridement of the nerve ends, including the removal of perineurial remnants, hematomas, and damaged axons. 5–6 sutures are usually placed on the connective tissue sheath using atraumatic needles and 6/0 or 7/0 sutures, while the nerve trunks must be approximated without significant tension and twisting, and the nerve fibers themselves are not punctured.
What microsurgical requirements apply to nerve suture placement?
When applying an epineural suture using microsurgical technique, the nerve fibers themselves should not be punctured: the suture is placed on the epineurium. The ends of the nerve are approximated without twisting and significant tension; to eliminate tension, mobilization of the nerve trunk is performed.
Class and exam questions
What is an absolute indication for nerve surgery in entrapment syndrome?
Absolute indications are severe deficits of sensory and motor functions, as well as rapid progression of symptoms.
What is the essence of surgical intervention in nerve compression?
The operation consists of performing neurolysis — dissection of tissues compressing the nerve, to create optimal conditions and prevent its trauma.
What structures form the tarsal tunnel?
Anteriorly, the canal is bounded by the medial malleolus, laterally by the calcaneus, and medially by the fibrous band of the flexor retinaculum.
What is used in the postoperative period after nerve release?
In the postoperative period, a wide arsenal of physiotherapeutic agents and neurostimulators is actively used.
What else to study on this topic
- Technique of nerve suture execution in complete anatomical transection
- Detailed anatomy and biomechanics of the ankle joint in the context of injuries
- Protocols for the use of neurostimulators in the postoperative period
- Differential diagnosis of vascular versus neurogenic intermittent claudication
- Features of rehabilitation after peripheral nerve surgery
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