Imaging description

Imaging features of intraneural ganglion cyst of the peroneal nerve are the same as those of ganglion cyst of other locations. Intraneural ganglion occurs within a variety of nerves, but the most frequent location is the common peroneal nerve at the fibular neck. MRI may reveal an elongated, lobulated mass posterolateral to the fibular neck (Figure 56.1). The mass shows homogeneous low signal intensity on T1-weighted images, high signal intensity on T2-weighted images, and no to minimal peripheral enhancement after IV contrast. The lesions are often closely related to the proximal tibiofibular joint. Ultrasound shows a hypoechoic lesion along the common peroneal nerve.

Importance

Intraneural ganglions are typically contained in the epineurium of the peripheral nerve, frequently associated with nerve palsy due to compression. Early diagnosis and surgical removal is important to prevent permanent axonal injuries. Previous report on patients with intraneural ganglion of the peroneal nerve noted that the patients with good results either had no preoperative paralysis or had footdrop for four months or less before surgical decompression.

Typical clinical scenario

Male patients are more commonly affected (about 80%) than female with a peak incidence in the fourth decade of life. The patient presents with a palpable mass on the lateral aspect of the fibular head with a varying degree of symptoms from compression of the common peroneal nerve. The symptoms include pain in the anterolateral aspect of the leg and dorsum of foot, muscle weakness of the anterior compartment of the leg, and complete peroneal nerve palsy. Sensory loss is usually less obvious than motor deficit.