Decompression of the Lateral Sural Cutaneous to Relief ChronicExertional Lower Leg Pain After More Than 30 Years - Rare or often Overlooked ? Andreas Gohritz, MD and Dirk J. Schaefer, MD Plastic, Reconstructive, Aesthetic and Hand Surgery, University Hospital, Basel, Switzerland

Introduction: The Lateral sural Case report: - 65-yo male, severe bilateral exertional lower

cutaneous72 Lateral Sural Cutaneousnerve Nerve Entrapment(LSCN) derives leg pain since more than 3813decades from a variable network of both bursitis- [2 ]. Induring the most recentjogging report, in 2013,> 20 Khalilmin et al. - not during normal walking. [ 1 ] reported a patient with an isolated LCNC entrapment the and the common from a- fi brousLocalized band of tissue. Thestabbing patient had temporary/ burning pain of lateral calf with relief from local anesthetic and steroid injections; he opted fibular nerve and supplies the for surgery (seeirradiation below) with good reliefinto 1 yearhis later.lateral foot. upper lateral aspect of the lower - Cutaneous sensitivity, tenderness and positive Tinel sign limb below the knee (Fig. 1). Physical Examover LSCN, motor function and reflexes normal. Isolated entrapment Posteriorof femoralthis Cutaneous- sensitivityMultiple or hyperalgesiaconservative may be seen in the dis-treatments, including local injections cutaneous nerve tribution of the LSCN. Careful palpation or Tinel’s test over nerve has only been Sciaticreported nerve the course of theand nerve frombilateral the popliteal fossasurgical to the fi bular fasciotomies (to treat exercise- head may occasionally reveal sensitivity of an entrapped or Inferior cluneal otherwise infl amed LSCN (Fig. 72.5 ). Motor function (spe- very rarely. induced compartment syndrome) failed cifi cally the tibialis anterior, tibialis posterior, and extensor hallucis- longusPainfree muscles) and refl afterexes should2 beinfiltrations normal. of the LSCN with Lidocain 2% Fig. 2: Tender points marked preoperatively over lateral calf. DifferentialResults Diagnosis: - (TablePreoperative 72.3 ) marking of LSCN tender point over Fig. 3: Decompression by cutting The most common cause of lateral calf pain is an L5 radicu- lopathylateral [1 ]; however,calf if the symptoms(Fig. are2), purelynerve sensory inderived from the common peroneal strong fibrous band (extension Common peroneal nature, LSCN pathology may be the etiology. Given the sig- of deep fascia extending into nerve nerve bilaterally and was decompressed by cutting a strong nifi cant heterogeneity in origin and course of all of the nerves Lateral sural of the sural complex, cutaneous pain in the posterolateral gastrocnemius / peroneus cutaneous nerve fribrous band (deep facia extending into the gastrocnemius Medial sural lower leg must be thought of in terms of all of the potential Peroneal longus muscle). cutaneous nerve contributors to the region. communicating and peroneus longus muscle) (Fig. 3). branch The superior border of the LSCN territory abuts that of Fig. 4: Inconspicious scar 3 months postop at lateral calf Tibial nerve the lateral- Fadingfemoral cutaneousof nervesymptoms (see Chap. 61 ) anteriorlyand patient completely painfree since Sural nerve and the posterior femoral cutaneous nerve posteriorly (see Chap. about 62 ). The anteromedial1 month border postoperativlyof the LSCN territory , healing uneventful (Fig. 4). Conclusion: The LSCN is a little-known and cutaneous abuts that of the intermediate cutaneous nerve of the thigh (and theDiscussion patellar plexus ) proximally: - andOnly that of 4the reportssaphe- of LSCN entrapment published sensory nerve with high anatomic variability. nous nerve (see Chap. 59 ) distally. The posteromedial border Lateral dorsal of the LSCNto date territory, overlapsthe signififirst cantlycase with thatin of the1998 - only 2 progressed to surgery Mononeuropathy of this nerve should be considered in cutaneous nerve Lateral medial sural cutaneous nerve and the sural nerve itself (see Lateral calcaneal Chap. 71and ). The inferiorthis bordermay of thefirst LSCN abutsbilateral that of the occurance succesfully treated by pure sensory symptoms at the lateral calf. Due to difficult Medial calcaneal branches superfi cial fi bular/peroneal nerve (see Chap. 68 ). Pain branches emanatingsurgical from a lesiondecompression of one of these neighbors .should diagnosis, entrapment of the LSCN may be more common Fig. 72.3 Nerves of the lower extremity (Image courtesy of Springer) present- withDiagnosis a distribution moreof entrapment typical of the nerve indifficult due to variable innervation question, but when confi ned to a “border zone,” the diagno- than its rare description in literature. Surgical neurolysis Fig. 1: Anatomy of the Lateral sural sis mayin becomelateral more elusive.calf and the obscurity of this nerve compressed by may resolve pain and paraesthesia if conservative cutaneous• There is nerve (LSCN) complete heterogeneity of the location of the anastomosis in terms of the level of the calf. local tumors (cysts), tendons or fascial structures. measures have failed. Diagnostic Tests (Table 72.4 )

Entrapment The diagnosis is usually confi rmed by electrodiagnostics. Needle EMG should be normal, and there should be no delay Only three reports of entrapment of the LSCN were found in in the sensory nerve action potential (SNAP) of the sural the literature, and all three referred to the nerve as the lateral nerve or the across the fi bular head. cutaneous nerve of the calf. The fi rst report, in 1998, Campagnolo et al. [12 ] described a technique of NCV, plac- described entrapment of the nerve as it pierced the tendon of ing the stimulating electrodes 2 cm posteriomedial and 4 cm the [11 ]. The second report, in 2006, proximal to the center of the fi bular head, with the recording described entrapment of the nerve by a peri-popliteal cystic electrode placed 12 cm distally to the stimulation site.