Natural history of sensory nerve recovery after cutaneous nerve injury following foot and ankle surgery

Cutaneous nerve injury is the most common complication following foot and ankle surgery. However, clinical studies including long-term follow-up data after cutaneous nerve injury of the foot and ankle are lacking. In the current retrospective study, we analyzed the clinical data of 279 patients who underwent foot and ankle surgery. Subjects who suffered from apparent paresthesia in the cutaneous sensory nerve area after surgery were included in the study. Patients received oral vitamin B12 and methylcobalamin. We examined final follow-up data of 17 patients, including seven with sural nerve injury, five with superficial peroneal nerve injury, and five with plantar medial cutaneous nerve injury. We assessed nerve sensory function using the Medical Research Council Scale. Follow-up immediately, at 6 weeks, 3, 6 and 9 months, and 1 year after surgery demonstrated that sensory function was gradually restored in most patients within 6 months. However, recovery was slow at 9 months. There was no significant difference in sensory function between 9 months and 1 year after surgery. Painful neuromas occurred in four patients at 9 months to 1 year. The results demonstrated that the recovery of sensory function in patients with various cutaneous nerve injuries after foot and ankle surgery required at least 6 months.     

Two modes of cutaneous reinnervation following peripheral nerve injury.

The return of sensation to the foot following sciatic nerve crush injury was analyzed behaviorally and electrophysiologically in the rat. Functional recovery begins within four days. Its early phase is accounted for by expansion of the functional distribution of intact neighboring fibers of the saphenous n. It occurs even if the sciatic n. is ligated, and it disappears with section of the saphenous n. Accompanying this functional expansion we began to encounter in electrophysiological recordings from the saphenous n., fibers with unusually large receptive fields (RF's) extending onto the plantar surface of the foot, well beyond their limits in intact rats. All of the expanded RF's were high threshold mechanoreceptors. On about the twentieth day after crushing, the regenerating sciatic n. began to make a functional contribution. This was seen by return of sensation to zones not invaded by the saphenous n. and by the onset of sensation in rats in which the saphenous n. had previously been ligated. With return of the sciatic n. the expanded distribution of the saphenous n. went back to its original boundaries. Correspondingly, we could no longer find expanded saphenous n. RF's. We conclude that cutaneous reinnervation begins with the collateral expansion of high threshold afferents from intact neighboring nerves. This alien innervation is later replaced upon regeneration of the original nerve.     

The lateral femoral cutaneous nerve: nerve conduction technique.

In 58 subjects without signs or symptoms of peripheral nerve disorders, an antidromic sensory nerve conduction study was performed on the lateral femoral cutaneous nerve. Anatomic dissections were performed on two cadavers to reveal the course of the nerve and to localize the optimal stimulation and recording sites. Mean sensory nerve action potential latency was measured at 1.7 msec (SD = 0.23) with a mean amplitude of 10.5 microV (SD = 4.0). The optimal localization of recording and stimulating surface electrodes and nerve conduction technique procedures are discussed. Reliable electrophysiologic criteria, according to age and body mass index, are obtained.     

Normative data for lateral femoral cutaneous nerve SEPs.

AIMS OF THE STUDY: To determine normative values for somatosensory evoked potentials (SEPs) of the lateral femoral cutaneous nerve (LFCN). METHODS: The LFCN was stimulated at two points, one located 1 cm lateral to the midpoint of a line joining the anterior superior iliac spine (ASIS) and the patella (31 subjects), and the other one located 12 cm distal to the ASIS (24 subjects). Recordings were performed at Cz' (2 cm behind Cz)-Fz. RESULTS: Reproducible SEPs were obtained in all but one of the 31 subjects to ASIS-patella midpoint (mean P1 latency: 33.2+/-3.5 ms, mean side-to-side difference: 2.0+/-1.6 ms) and in all but three of the 24 subjects to stimulation 12 cm distal to the ASIS (mean P1 latency: 30.9+/-3.3 ms, mean side-to-side difference: 2.2+/-1.7 ms). CONCLUSIONS: Reliable SEPs can be obtained to LFCN stimulation. It is easier and, therefore, more convenient to stimulate the ASIS-patella midpoint.     

Anterior interosseous nerve syndrome following cutdown catheterization.

Traumatic neuropathy following intravenous catheterization by means of a cutdown at the antecubital fossa resulted in inability to flex the tip of the index finger and thumb. The impaired pincer grasp that results causes considerable handicap when the dominant hand is involved.     

Pressure neuropathy of the posterior femoral cutaneous nerve

Neuropathy of the posterior femoral cutaneous nerve by compression is described in three cases. The case history and the physical examination are the most important clues to diagnoses.     

Distal lesion of the lateral femoral cutaneous nerve

We report three patients with a typical clinical picture of unilateral meralgia paresthetica in whom routine nerve conduction studies were normal. However, cortical somatosensory evoked potentials were absent after lateral femoral cutaneous nerve (LFCN) stimulation on the affected side. After stimulation of the LFCN in the anterosuperior iliac spine (ASIS) region and recording the responses distal to conventional sites (20 cm from the ASIS), sensory nerve action potentials (SNAPs) were absent in the symptomatic leg, but present in the normal leg. We suggest that thigh paresthesias may be caused by a distal LFCN lesion. Eliciting this requires recording SNAPs distal to conventional sites.     

Isolated posterior femoral cutaneous neuropathy following intragluteal injection

Isolated posterior femoral cutaneous nerve lesions are rarely encountered. Electrophysiological documentation has only been made in a few cases. In this study we evaluated a 22‐year‐old woman with sensory loss and pain in the lower buttock and posterior thigh after left gluteal intramuscular injection. We assessed the posterior femoral cutaneous nerve using an accepted conduction technique. The results showed a normal response on the asymptomatic side, but no response on the symptomatic side. Muscle Nerve, 2009     

Variability in conduction of the lateral femoral cutaneous nerve

The purpose of this study was to establish a reliable technique for assessing conduction in the lateral femoral cutaneous nerve (LFCN), bearing in mind its anatomical variation. Based on our anatomical study, normative values were obtained in 40 healthy nerves. The optimal stimulation site was located 1 cm or more media 16470526 l to the anterior superior iliac spine (ASIS) in 93% of cases and over the ASIS in 7%. Sensory nerve action potentials (SNAPs) were recorded simultaneously along an imaginary line between the ASIS and the lateral border of the patella and 2 cm medial to this line. Side-to-side variability in amplitude was 31% for the recording from the line and 30% for the medial recording. The variability significantly decreased to 16% when the higher value of each side was compared. Therefore, the measurement of higher amplitude recorded at two different sites may minimize interside variability and improve the diagnostic utility of the LFCN conduction study.     

Identity of myelinated cutaneous sensory neurons projecting to nocireceptive laminae following nerve injury in adult mice

It is widely thought that, after peripheral injury, some low‐threshold mechanoreceptive (LTMR) afferents “sprout” into pain‐specific laminae (I–II) of the dorsal horn and are responsible for chronic pain states such as mechanical allodynia. Although recent studies have questioned this hypothesis, they fail to account for a series of compelling results from single‐fiber analyses showing extensive projections from large‐diameter myelinated afferents into nocireceptive layers after nerve injury. Here we show that, in the thoracic spinal cord of naïve adult mouse, all myelinated nociceptors gave rise to terminal projections throughout the superficial dorsal horn laminae (I–II). Most (70%) of these fibers had large‐diameter axons with recurving flame‐shaped central arbors that projected throughout the dorsal horn laminae I–V. This morphology was reminiscent of that attributed to sprouted LTMRs described in previous studies. After peripheral nerve axotomy, we found that LTMR afferents with narrow, uninflected somal action potentials did not sprout into superficial laminae of the dorsal horn. Only myelinated noiceptive afferents with broad, inflected somal action potentials were found to give rise to recurving collaterals and project into superficial “pain‐specific” laminae after axotomy. We conclude that the previously undocumented central morphology of large, myelinated cutaneous nociceptors may very well account for the morphological findings previously thought to require sprouting of LTMRs. J. Comp. Neurol. 508:500–509, 2008. © 2008 Wiley‐Liss, Inc.     

Traumatic carotid artery occlusion following blunt cervical injury.

Two cases of overlooked, traumatic unilateral occlusion of the carotid artery are reported. Postmortem revealed occlusion of the internal carotid artery in one case and that of the common carotid artery in another. The progression of the morbid state, along with the management with emphasis on the significance of the carotid angiogram and follow-up repeated computed tomography are mentioned. Although traumatic occlusion of the common carotid artery is not as common as that of the internal carotid artery, both entities are well known to produce morbidity and mortality.     

Damage to the lateral cutaneous femoral nerve after transfemoral angiography]

We report on two patients with lesions of the lateral cutaneous nerve of the thigh after transfemoral angiography. Symptoms were hypesthesia, dysesthesia and hypalgesia of the right lateral thigh. One patient had no hematoma, the other a hematoma of the medial thigh which did not enlarge thigh circumference. Both patients had had a tight pressure bandage applied for 24 hours. There were no signs of a femoral nerve lesion. Both patients were severely distressed by paresthesia. The numbness subsided after three weeks in one patient, but pain persisted. The other patient had symptoms for over six months. The lateral cutaneous nerve of the thigh is located distinctly lateral to the puncture site in transfemoral angiography. Hence we suggest that the nerve lesion was caused neither by the puncture itself nor by a hemorrhage, but by the tight bandage.     

Postoperative lateral femoral cutaneous neuropathy.

Lateral femoral cutaneous (LFC) neuropathy was diagnosed in a woman who developed pain and paresthesias in the right thigh 6 days after abdominal hysterectomy by a suprapubic approach. After surgery, the patient slept in the fetal position to control the postoperative suprapubic pain. The LFC neuropathy improved with therapy including avoidance of hip flexion during sleep. Prolonged postoperative hip flexion to relieve the abdominal incisional pain provides an explanation for LFC neuropathy after abdominal surgery when the onset of symptoms is delayed.     

Skew deviation following vestibular nerve surgery

Eighteen consecutive patients undergoing vestibular nerve surgery underwent pre- and postoperative examination of ocular motility. Five patients developed a skew deviation following surgery, with the lower eye on the operated side and an incomitant pattern of deviation in all cases. Three patients experienced diplopia lasting from 1 day to 6 months. The magnitude of skew deviation was increased by head tilt away from the operated side in only 1 case. The development of skew deviation was not determined by preoperative ocular alignment or binocular function, or any particular type or pattern of vestibular disease. There was an association with large changes in ocular torsion and subjective visual vertical, which correlated with lesser degrees of canal paresis to preoperative caloric testing on the operated side. No patient developed a head tilt postoperatively. There is a gradation of responses to surgical vestibular deafferentation in humans, skew deviation only occurring in patients suffering marked changes in subjective visual vertical and ocular torsion.     

Patterns of nerve injury and neuropathic pain in ischemic neuropathy after ligation-reperfusion of femoral artery in mice

Ischemia is an important etiology of painful neuropathies. We generated a mouse system of ischemic neuropathy by ligation-reperfusion of the femoral artery to mimic neuropathic pain and nerve injury patterns observed clinically. Mice exhibited spontaneous neuropathic pain behaviors, which were most obvious after ischemia for 5 h. Mechanical and cold allodynia developed by post-operative day (POD) 7 and persisted through the experimental period up to POD 56. Neuropathic pain behaviors were alleviated with intraperitoneal gabapentin (50 and 100 mg/kg) in a dose-dependent manner. Large-fiber deficit assessed with nerve conduction studies was demonstrated by reduced amplitudes of the compound muscle action potential (CMAP) on POD 7 (48.4% of the control side, p < 0.001). Small-fiber impairment was demonstrated by decreased epidermal nerve density (END) on POD 7 (29.1% of the control side, p < 0.001). Reductions in CMAP amplitudes and ENDs persisted through POD 56. Our system replicated the clinical manifestations of ischemic neuropathy: (1) neuropathic pain with cold and mechanical allodynia and (2) nerve injury to both large and small fibers with pathologic and physiologic evidence. This system produced by a simple procedure provides an opportunity to investigate mechanisms and further treatments of ischemic neuropathy on genetically engineered mice.