Abstract
The common peroneal nerve, also known as the common fibular nerve, is commonly entrapped or compressed as it crosses the head of the fibula; it is known as cross leg or yoga palsy. Symptoms of entrapment of the common peroneal nerve at this anatomic location are numbness and foot drop. The common peroneal nerve is also subject to compromise from a number of pathologic conditions including neuropathy, leprosy, and vasculitis. Tumors of the common peroneal nerve as well extrinsic masses, including ganglion cysts. may also entrap the nerve. Plaster casts and orthotic braces must be carefully fitted to avoid compression of the nerve. The common yoga position vajrasana has also been implicated in the evolution of this lower extremity nerve entrapment.
Patients suffering from common peroneal nerve entrapment will complain of both motor and sensory symptoms. Burning, tingling, numbness, and dysesthesias in the sensory distribution of the common peroneal nerve, which may worsen at night, are frequent complaints as is allodynia. Weakness of the dorsiflexors and everters of the foot and ankle are often present and the patient may adopt a steppage gait to compensate for the drop foot.
Keywords
common peroneal nerve entrapment, foot drop, leprosy, vasculitis, neuropathy, yoga palsy, diagnostic sonography, Baker’s cyst, steppage gait, ultrasound guided injection
ICD-10 CODE G57.30
The Clinical Syndrome
The common peroneal nerve, also known as the common fibular nerve, is commonly entrapped or compressed as it crosses the head of the fibula; it is known as cross leg or yoga palsy. Symptoms of entrapment of the common peroneal nerve at this anatomic location are numbness and foot drop. The common peroneal nerve is also subject to compromise from a number of pathologic conditions including neuropathy, leprosy, and vasculitis. Tumors of the common peroneal nerve as well extrinsic masses including ganglion cysts, may also entrap the nerve. Plaster casts and orthotic braces must be carefully fitted to avoid compression of the nerve ( Box 119.1 ). The common yoga position vajrasana has also been implicated in the evolution of this lower extremity nerve entrapment ( Fig. 119.1 )
External compression
During anesthesia, coma, sleep, bed rest
Plaster casts, braces
Habitual leg crossing
Sitting cross-legged
Prolonged squatting, kneeling
Direct trauma
Blunt injuries, lacerations
Fractures of the fibula
Adduction injuries and dislocations of the knee
Surgery and arthroscopy in popliteal fossa and knee
Traction injuries
Acute ankle injuries
Masses
Ganglia, Baker’s cysts, callus, fibular tumors, osteomas, hematomas
Tumors
Nerve sheath tumors
Nerve sheath ganglia
Lipomas
Entrapment
In the fibular tunnel
Anterior (tibial) compartment syndrome
Vascular
Vasculitis, local vascular disease
Diabetes mellitus: susceptibility to compression, ischemic damage
Leprosy
Idiopathic
Signs and Symptoms
Patients suffering from common peroneal nerve entrapment will complain of both motor and sensory symptoms. Burning, tingling, numbness, and dysesthesias in the sensory distribution of the common peroneal nerve, which may worsen at night, are frequent complaints, as is allodynia ( Fig. 119.2 ). Weakness of the dorsiflexors and evertors of the foot and ankle are often present, and the patient may adopt a steppage gait to compensate for the drop foot ( Fig. 119.3 ).
