Aberrant cutaneous nerve of the thigh arising from the sciatic nerve in the human

An aberrant cutaneous nerve of the thigh arising from the peroneal portion of the human sciatic nerve or common peroneal nerve was observed in 9 cases (4.6% of sides). After giving a branch to the short head of the biceps femoris muscle and a branch to the knee joint, this cutaneous nerve reaches the subcutaneous tissue by passing between the short head of the biceps femoris and the vastus lateralis or by piercing through the biceps femoris. The authors presume that the cutaneous nerve shows the presence of the potential cutaneous nerve routes from the common peroneal nerve to the skin of the lateral aspect of the thigh.     

Crossed leg palsy; with report of a recurrent case

A form of peroneal palsy may be caused by crossing the legs. Two physical factors-pressure and tension - are the basic causes, although other factors may be contributory. Direct pressure is applied by the bones of the two legs, compressing the peroneal nerve between them at its superficial part near the head and neck of the fibula. The palsy may be overlooked as an integral part of a widespread disorder so that careful evaluation and observation of the patient's habits are required. Detection becomes especially difficult when the palsy is bilateral, for then the lesion by virtue of its symmetry blends more readily with associated polyneuritis. A case of recurrent peroneal palsy due to crossing the legs in a prolonged postoperative convalescence is reported in detail.     

CROSSED LEG PALSY with Report of a Recurrent Case

A form of peroneal palsy may be caused by crossing the legs. Two physical factors—pressure and tension — are the basic causes, although other factors may be contributory. Direct pressure is applied by the bones of the two legs, compressing the peroneal nerve between them at its superficial part near the head and neck of the fibula.The palsy may be overlooked as an integral part of a widespread disorder so that careful evaluation and observation of the patient''s habits are required. Detection becomes especially difficult when the palsy is bilateral, for then the lesion by virtue of its symmetry blends more readily with associated polyneuritis. A case of recurrent peroneal palsy due to crossing the legs in a prolonged postoperative convalescence is reported in detail.     

Innervated island flaps in morphofunctional vulvar reconstruction

In this article, the authors present their own experience in vulvar reconstruction following vulvectomy using two different innervated island flaps according to the size and site of the defect. Island-flap mobilization is possible thanks to the rich blood supply of the perineal region. The methods described are a "V-Y amplified sliding flap from the pubis" and a "fasciocutaneous island flap" raised from one or both gluteal folds. The V-Y amplified sliding flap from the pubis is indicated when the defect is symmetric and located anteriorly. This flap is harvested from the pubis and vascularized by the deep arterial network of the pubis. Sensory innervation is provided by branches of the ileo-inguinal nerve. The fasciocutaneous island flap, raised from one or both gluteal folds, can be used following hemivulvectomy or radical vulvectomy, respectively, to cover posteriorly located defects. Vascularization is provided by the musculocutaneous perforating branches of the pudendal artery, whereas sensory innervation is maintained through the perineal branches of the pudendal nerve. Twenty-two patients have undergone reconstructive surgery of the vulvar region from 1989 to date. On 14 patients, a V-Y amplified sliding flap was used; on 7 patients, reconstruction was carried out by island flaps raised from the gluteal fold. Both techniques are compatible with inguino-femoral lymphadenectomy, and they allow for a correct morphofunctional reconstruction and provide good local sensibility. The final result is aesthetically satisfactory, as all final scars are hidden in natural folds.     

Decompression of the common peroneal nerve: experience with 20 consecutive cases

A retrospective review of 20 patients with common peroneal nerve palsy treated with decompression between 1986 and 1997 was undertaken. Subjects were evaluated preoperatively and postoperatively by electromyography, nerve conduction, and clinical measures. The mean interval between the onset of symptoms to surgery (operative delay) was 15.9 months. The mean postoperative follow-up was 32.2 months with a minimum follow-up of 1 year. Decompression was performed at the level of the fibular neck and slightly distally at the tendinous origin of the peroneus longus using a standard approach to release tight fascial structures or scar tissue. External neurolysis was performed using the operating microscope in two cases for which scarring of the nerve was identified intraoperatively. Postoperatively, 19 of 20 patients showed improvement in ankle dorsiflexion as assessed by the Medical Research Council scale. Electromyographic examination was useful in the preoperative evaluation and selection of patients for decompression surgery. In conclusion, decompression even after a 1-year delay may offer benefit and suggest early intervention in patients with a severe lesion.     

Efficiency of reinnervation of neonatal rat muscle of original and foreign nerves

Formation of neuromuscular connections in mammals may involve a hierarchy of efficiency of synapse formation at a stage when motor nerves have already contacted muscle fibers and during the transitional period of multiple innervation. In an attempt to test for such a hierarchy, we examined, in neonatal rats, the relative efficiency of reinnervation by foreign or original nerves implanted simultaneously in a large muscle so that competition for muscle fibers was minimized. The tibial nerve, containing gastrocnemius nerve fibers, and the “foreign” peroneal nerve were implanted into the denervated lateral gastrocnemius muscle. One to five months later, indirect tetanic tensions obtained upon stimulating the implanted nerves were measured by isometric techniques and were compared to contralateral control muscles. When both nerves were implanted side by side at the end-plate region, approximately equal tetanic tensions were obtained at the time of testing. The same result was also obtained when the tibial and common peroneal nerves were implanted into non-end-plate and end-plate regions, respectively. However, in the reverse experiment, the tibial nerve implanted at the end-plate region produced significantly higher tetanic tension than the peroneal nerve at the non-end-plate site in the same muscle. Thus, the original nerve, compared to a foreign nerve, appeared to reinnervate neonatal muscle more effectively, but this was only revealed under conditions where access to former end-plate regions was unequal.     

Age-related changes of elements with their relationships in human cranial and spinal nerves

To elucidate compositional changes of peripheral nerves with aging, the authors investigated age-related changes of elements and their relationships in the optic, trigeminal, vagus, median, radial, ulnar, femoral, sciatic, tibial, and common peroneal nerves by inductively coupled plasma-atomic emission spectrometry. The subjects consisted of 10 men and 12 women, ranging in age from 65 to 91 yr. It was found that although accumulations of Ca and P occurred only in the trigeminal nerve at old age, it hardly occurred in the optic, vagus, median, radial, ulnar, femoral, sciatic, tibial, and common peroneal nerves at old age. The average contents of Ca and P were three and two times higher in the trigeminal nerve than in the other nine kinds of nerve, respectively. Likewise, the average content of Mg was a little higher in the trigeminal nerve compared with the other nerves. With regard to the relationships among elements, significant direct correlations were found among the contents of Ca, P, S, and Mg in most, but not all, 10 kinds of nerve. In the trigeminal nerve, a significant inverse correlation was found between the contents of S and the other elements, such as Ca, P, and Mg. Regarding the relationships between the contents of S and other elements, the nerves, except for the trigeminal nerve, differed from those found in the arteries previously reported.     

The harvest and clinical application of the superficial peroneal sensory nerve for grafting motor and sensory nerve defects.

Potential donor nerves for autografting are finite and usually limited to cutaneous nerves of the extremities. The superficial peroneal nerve is the major lateral branch of the common peroneal nerve that innervates the peroneus longus and brevis muscles and provides sensation to the lateral aspect of the lower leg and the dorsal foot. It has generally been overlooked as a potential donor of nerve autografts. Cadaver dissections were performed on 10 fresh lower extremity specimens to investigate the anatomic characteristics of the superficial peroneal nerve and to refine a harvesting technique for the nerve. Thirty-one patients underwent nerve grafting of 39 upper and lower extremity nerves using the superficial peroneal donor. There were nine median nerves, four ulnar nerves, two radial nerves, two brachial plexus lesions, 16 digital nerves, and six lower extremity nerves grafted. The superficial peroneal nerve provided a consistently long donor, comparable in length to the sural nerve. The anatomic pattern is consistent, the patient positioning is simple, the surgical harvesting technique is straightforward, and the donor defect is acceptable. The superficial peroneal nerve provides a safe and valuable donor nerve, particularly in cases where multiple or very long nerve grafts are required.     

Nerve regeneration through side-to-side neurorrhaphy sites in a rat model: a new concept in peripheral nerve surgery

Despite great improvement and refinements in nerve repair techniques, there were still problems in repair of peripheral nerve injuries for which proximal stumps were not available. In these circumstances for which classic end-to-end neurorrhaphy was impossible, new treatment modalities, benefiting by an adjacent healthy nerve, have been under investigation to overcome this problem. Therefore, end-to-side nerve repair with its modifications came to view and axonal passages through this site were shown. Moreover, the results were unsatisfactory or necessitating sacrifice of another healthy nerve. Three groups, containing 10 rats each, were included in the study. First was the control group, with end-to-end repair of the peroneal nerve. Second was the end-to-side repair group, in which the distal stump of the peroneal nerve trunk was anastomosed to the lateral side of the tibial nerve. The third was the side-to-side repair group. In this technique, 1-mm diameter epineural windows, both from peroneal and tibial nerve trunks facing each other, were removed and side-to-side neurorrhaphy was performed. After 3 weeks, as the second step, the peroneal nerve was sectioned proximally. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed by using walking track analysis. The number of myelinated fibers and fiber diameters were measured and an electron microscopic evaluation was carried out. Statistically, both in morphometric and gait analysis, the differences in values between the groups were significant in favor of the control group, followed by the side-to-side group. The study showed that axonal passage was possible with side-to-side technique and the functional results were satisfactory and superior to the end-to-side technique. Continuous supply of neurotrophic factors from their target cells was the probable cause of superior functional return in side-to-side repair, because both joining nerves were intact and healthy during the anastomosis procedure and after 3 weeks. It was concluded that this technique could be indicated in salvage of nerves in cases for which any intermediate segments would be removed, as in tumor ablation surgery, harvesting of nerve grafts, or both.     

Target-specific nerve regeneration through a nerve guide in the rat

Nerve regeneration across a gap in peripheral nerve has been achieved through various nonneural nerve guides in both lower and primate species. This technique can only be useful if the regenerated nerve cable grows specifically to and reinnervates the appropriate distal target. In this study, the proximal peroneal fascicle of rat sciatic nerve was inserted into the proximal limb of a Y-shaped nerve guide. Distal peroneal and tibial fascicles were placed within the two distal limbs of the same Y. The proximal peroneal nerve grew preferentially by a 2:1 ratio to the appropriate distal peroneal fascicle suggesting that target-specific reinnervation is possible through a nerve guide.     

Weak Ankles. A Study of Common Peroneal Entrapment Neuropathy

Twenty-three patients were seen with entrapment neuropathy in a two-and-a-half-year period. Symptoms consisted of pain, paresis, and paraesthesia in the distribution of the common peroneal nerve. Some degree of paresis was often present, which in five patients was severe enough to cause drop foot. In 20 patients decompression of the entrapped nerve at the neck of the fibula was quickly and completely successful. It is suggested that the ankle weakness which frequently follows sprains and other forced inversion injuries may often be at least partially due to entrapment of the common peroneal nerve.     

Results of management of facial palsy with microvascular free-muscle transfer

This paper reports our experience in facial reanimation using free innervated muscle transfer in 69 patients with long-term facial palsy. The majority of patients were treated in two stages with cross-facial nerve graft as the first stage and microvascular muscle transfer at the second stage. The gracilis muscle was used in 62 patients. A system of grading results has been utilized in the long-term evaluation. The overall final result was excellent or good in 51 percent of 47 patients who were available for follow-up. Although the results are not completely satisfactory, they justify the use of this approach to a difficult clinical problem. The results are improving as technical modifications to the procedure have evolved. The gracilis muscle is a reliable free transfer with internal anatomy conductive to use for reanimation of the paralyzed face. This type of transfer, in our experience, has proved superior to nonmicrosurgical methods for treatment of complete and severe incomplete facial palsy. The seventh cranial nerve is used in the innervation of the transferred muscle, the ipsilateral being preferable if available. The authors believe that use of the same cranial nerve is superior to methods that involve other cranial nerves, where spontaneity is often not achieved.     

Post-tetanic potentiation of reciprocal Ia inhibition in human lower limb.

The purpose of this study was to investigate how reciprocal Ia inhibition is changed during muscle fatigue of lower limb muscle, induced with a voluntary contraction or height frequency electrical stimulation. Reciprocal Ia inhibition from ankle flexors to extensors has been investigated in 12 healthy subjects. Hoffmann reflex (H-reflex) in the soleus muscle was used to monitor changes in the amount of reciprocal Ia inhibition from common peroneal nerve as demonstrated during voluntary dorsi or planterflexion and 50 Hz electrical stimulation induced dorsi or planterflexion. The test soleus H-reflex was kept at 20-25% of maximum directly evoked motor response (M response) and the strength of the conditioning common peroneal nerve stimulation was kept at 1.0 x motor threshold. At rest, weak la inhibition was demonstrated in 12 subjects, maximal inhibition from the common peroneal nerve was 28.8%. During voluntary dorsiflexion and 50 Hz electrical stimulation induced dorsiflexion, there absolute amounts of inhibition increased as compared to at rest, and decreased or disappeared during voluntary planterflexion and 50 Hz electrical stimulation induced planterflexion as compared to at rest. During voluntary or electrical stimulation induced agonist muscle fatigue, the inhibition of the soleus H-reflex from the common peroneal nerve was greater during voluntary dorsiflexion (maximal, 11.1%) and 50 Hz (maximal, 6.7%) electrical stimulation induced dorsiflexion than at rest. The inhibition was decreased or disappeared during voluntary planterflexion 50 Hz electrical stimulation induced planterflexion. It was concluded that the results were considered to support the hypothesis that alpha-motoneurones and la inhibitory intemeurones link to antagonist motoneurones in reciprocal inhibition. The diminished reciprocal Ia inhibition of voluntary contraction during muscle fatigue as compared to electrical stimulation, is discussed in relation to its possible contribution to ankle stability.     

Anatomical study of the facial nerve canal in comparison to the site of the lesion in Bell's palsy

The term Bell's palsy is used for the peripheral paresis of the facial nerve and is of unknown origin. Many studies have been performed to find the cause of the disease, but none has given certain evidence of the etiology. However, the majority of investigators agree that the pathophysiology of the palsy starts with the edema of the facial nerve and consequent entrapment of the nerve in the narrow facial canal in the temporal bone. In this study the authors wanted to find why the majority of the paresis are suprastapedial, i.e. why the entrapment of the nerve mainly occurs in the proximal part of the canal. For this reason they carried out anatomical measurements of the facial canal diameter in 12 temporal bones. By use of a computer program which measures the cross-sectional area from the diameter, they proved that the width of the canal is smaller at its proximal part. Since the nerve is thicker at that point because it contains more nerve fibers, the authors conclude that the discrepancy between the nerve diameter and the surrounding bony walls in the suprastapedial part of the of the canal would, in cases of a swollen nerve after inflammation, cause the facial palsy.     

A possible coordinating role for presynaptic inhibition

Conditioning stimuli were applied to the common peroneal or superficial peroneal nerve in acute experiments on anesthetized cats. Changes in the N₁-component of the dorsal cord potential evoked by stimulation of one of these nerves or of other nerves (tibial, deep peroneal) and changes in the amplitude of antidromic action potentials in the afferent fibers of these nerves were investigated. The degree of reinforcement of antidromic action potentials, reflecting the degree of depolarization of the afferent terminals, was found to be greater for the passive nerve than for the active to which the conditioning stimulus was applied. Inhibition of the N₁-component of the dorsal cord potential was deeper when a pair of stimuli was applied to two different nerves (under these conditions only the mechanism of presynaptic inhibition was activated) than when they were applied to the same nerve. It is concluded that presynaptic inhibition, by selectively controlling afferent volleys, can evidently play a coordinating role.     

Muscle Union Procedure in Patients with Paralytic Strabismus

To present the surgical outcomes of a muscle union procedure in patients with paralytic strabismus, this retrospective study included 27 patients with paralytic strabismus who underwent a muscle union procedure. In this procedure, the two vertical rectus muscles are united with the paralytic horizontal muscle without splitting the muscles. Postoperative ocular deviations, complications, surgical success rates, and reoperation rates were obtained by examining the medical records of the patients. Seventeen patients had a sixth cranial nerve palsy, seven patients had a third cranial nerve palsy, and three patients had a medial rectus muscle palsy after endoscopic sinus surgery. The mean preoperative angle of horizontal deviation in the primary position was 56 ± 21 prism diopters. The mean follow-up period was 12 ± 9 months. The mean final postoperative ocular deviation was 8 ± 13 prism diopters. The success rate was 74%, and the reoperation rate was 0%. No significant complications, including anterior ischemia, occurred in any of the patients. One patient exhibited an increase in intraocular pressure in the immediate postoperative period, but this resolved spontaneously within 1 week. Our muscle union procedure was effective in patients with paralytic strabismus, especially in patients with a large angle of deviation. This muscle union procedure is potentially a suitable option for muscle transposition in patients with paralytic strabismus who have large-angle deviation or a significant residual angle after conventional surgery.     

Fascia canals of the greater sciatic foramen and their practical importance

Fasciae and fat tissue spaces in the gluteal region, topography of the suprapiriform and infrapiriform foramina have been studied by means of a complex anatomical experimental technique. The suprapiriform foramen should be considered as a fascialosseous canal, as it is 4-4.5 cm long and 0.6-1.0 cm wide. It is formed by the upper margin of the greater sciatic notch covered with a thin fascia, fasciae of the gluteal and piriform muscles and the parietal layer of the pelvic fascia. The proper fascial vaginae of the upper gluteal vessels and nerves are adhered to fascial walls of the canal. This peculiarity is used for the method of ligation of the superior gluteal artery within the limits of the suprapiriform canal. The infrapiriform foramen is either narrow or wide enough (up to 2.0 cm in diameter). Inferior gluteal vessels at the level of the sacrospinous ligament go from the parietal layer of the pelvic fascia into the duplicature of the deeper layer of musculus gluteus maximus. The inferior gluteal nerve, above the lower margin of the piriform muscle, ajoining the vessels gets into the fissure of the parietal layer of the pelvic fascia, under the lower margin neurovascular fasciculus also goes through the fissure of the pelvic fascial parietal layer, downward and parallel to the inferior gluteal vessels. The knowledge of possible ways of connections through the canals of the greater sciatic foramen, fat tissue spaces at the subperitoneal level of the small pelvis and the gluteal region is of great practical value.     

Static otolithic drive alters presynaptic inhibition in soleus motor pool

The vestibular system has both direct and indirect connections to the soleus motor pool via the vestibulospinal and reticulospinal tracts. The exact nature of how this vestibular information is integrated within the spinal cord is largely unknown. The purpose of this study was to identify whether changes in static otolithic drive altered the amount of presynaptic inhibition in the soleus H-reflex pathway. Changes in static otolithic drive were investigated in sixteen healthy participants using a tilt table. Two presynaptic pathways (common peroneal and femoral) to the soleus H-reflex were tested in three weight conditions (supine, non-weight bearing, and weight bearing). The dependent variable was the peak-to-peak amplitude of the soleus H-reflex. Inhibition to the soleus motor pool through the common peroneal nerve pathway differed significantly during weight conditions and tilt. During tilt and non-weight bearing there was greater inhibition of the soleus H-reflex compared to supine, however, this effect was reversed during tilt and weight bearing. Facilitation from the femoral nerve pathway was reduced by tilt compared to supine, but this reduction was unaffected by weight condition. This supports a role of the vestibular system as providing complex, task-dependent presynaptic input to motoneurons in the lower limbs.     

Distribution of lumbar spinal evoked potentials and their correlation with stimulation-induced paresthesiae

In 7 awake patients with neuropathic lower extremity pain, spinal somatosensory evoked potentials (SEP) were elicited from the non-painful leg by electrical stimulation of the peroneal nerve and mechanical stimulation of the hallux ball. Recording was made epidurally in the thoraco-lumbar region by means of an electrode temporarily inserted for trial of pain-suppressing stimulation.In response to peroneal nerve stimulation, two major SEP complexes were found. The first complex consisted, as has been described earlier, of an initial positivity (P12), a spike-like negativity (N14), a slow negativity (N16) and a slow positivity (P23). The second complex consisted of a slow biphasic wave, conceivably mediated by a supraspinal loop. Both complexes had a similar longitudinal distribution with amplitude maxima at the T12 vertebral body.The SEP evoked by mechanical hallux ball stimulation had a relatively small amplitude, and there was no significant second complex. The relationship between stimulus intensity and SEP amplitude was negatively accelerating.The longitudinal distribution of spinal SEP was compated with the somatotopic distribution of paresthesiae induced by stimulation through the epidural electrode. It was found that stimulation applied at the level of maximal SEP generally induced paresthesiae in the corresponding peripheral region. Therefore, spinal SEP may be used as a guide for optimal positioning of a spinal electrode for therapeutic stimulation when implanted under general anesthesia.An attempt was made to record the antidromic potential in the peroneal nerve elicited from the dorsal columns by epidural stimulation. The antidromic response was, however, very sensitive to minimal changes of stimulus strength and body position of the patient, and was also contaminated by simultaneously evoked muscular reflex potentials.Thus, peripheral responses evoked by epidural stimulation appeared too unreliable to be useful for the permanent implantation of a spinal electrode for therapeutic stimulation.