Martin-Gruber anastomosis and unusual sensory innervation of the fingers: report of a case.

We report the electrophysiological study of a patient with carpal tunnel syndrome who, besides the features of median nerve entrapment at the wrist, showed an aberrant motor innervation of Martin-Gruber type and an unusual distribution of the sensory innervation of the fingers. Studies based on collision between sensory volleys showed that the fibers supplying the anomalous innervation did not follow the same path as the aberrant motor fibers. This finding is consistent with the hypothesis that Martin-Gruber anastomosis is made up of motor axons only, and supports the idea that other abnormalities of innervation may be found in patients with Martin-Gruber anastomosis.     

舌下-面神经吻合术治疗前庭神经鞘瘤术后面瘫

目的 探讨舌下-面神经吻合术治疗前庭神经鞘瘤术后面瘫的效果、策略和显微外科技巧.方法 回顾性分析16例行舌下-面神经吻合术患者的临床和随访资料.结果 舌下-面神经吻合术与肿瘤切除的时间间隔为1-13个月(平均7.6个月).术前面神经功能House-Brackmann分级Ⅵ级13例,Ⅴ级3例.术后Ⅱ级2例,Ⅲ级10例,Ⅳ级4例;15例患者闭眼能力恢复理想,恢复了静态时面部对称性和某些随意运动.结论 舌下-面神经吻合术是一种行之有效的治疗手段,手术时机的把握和显微外科操作技术是取得满意临床效果和提高患者生活质量的保证.     

Autologous nerve anastomosis versus human amniotic membrane anastomosisA rheological comparison following simulated sciatic nerve injury

The sciatic nerve is biological viscoelastic solid,with stress relaxation and creep characteristics.In this study,a comparative analysis of the stress relaxation and creep characteristics of the sciatic nerve was conducted after simulating sciatic nerve injury and anastomosing with autologous nerve or human amniotic membrane.The results demonstrate that,at the 7 200-second time point,both stress reduction and strain increase in the human amniotic membrane anastomosis group were significantly greater than in...     

The all ulnar motor hand without forearm anastomosis

Anomalous ulnar innervation of intrinsic hand muscles, inferred in a number of clinical series, has been documented only rarely in electrophysiological studies. Using near-nerve and standard conduction studies we evaluated 2 cases with nearly exclusive ulnar innervation of hand muscles. There was no evidence of anomalous communication in the forearm. Digital sensory fibers were normally distributed in median and ulnar nerves. The anomalous motor innervation most likely results from palmar communication between ulnar and median branches (Riche-Cannieu anastomoses). The normal distribution of digital afferents suggests that such anastomoses are formed primarily by motor axons.© 1995 John Wiley &Sons, Inc.     

Hemihypoglossal-facial nerve anastomosis for facial nerve palsy

BACKGROUND AND PURPOSE : Commonly used classic hypoglossal (CN XII) to facial nerve (CN VII) anastomosis has the disadvantage of tongue hemiatrophy. Thus, various attempts have been made to modify this method to reduce the tongue damage. The aim of this report was to present the results of hemihypoglossal-facial nerve anastomosis (HHFA) technique in relation to facial muscles reanimation and hemitongue atrophy. MATERIAL AND METHODS : The first 7 consecutive patients who underwent CN VII anastomosis with half of the CNXII, for which the follow-up period exceeded 12 months, were analysed. During the procedure, CN VII was transected as proximally as possible after drilling the mastoid process. CN XII was separated longitudinally into two parts at a short distance to allow suture of the stumps without any tension. One half of CN XII was transected and sutured to the distal stump of CN VII. Recovery from facial palsy was quantified with the House-Brackmann grading system (HB). Tongue function was assessed according to the scale proposed by Martins. RESULTS : Features of initial reinnervation of facial muscles were visible after 6 months in all 7 patients. All patients achieved satisfactory outcome of CN VII regeneration (HB grade III) until the last control examination (12-27 months after surgery, mean 16). No or minimal tongue atrophy without deviation (grades I-II according to the Martins scale) was found in 4 patients. Mild hemiatrophy with tongue deviation < 30 degrees (grade III) was visible in 3 patients. CONCLUSIONS : In our experience, HHFA is effective treatment of facial palsy and gives a chance to reduce damage of the tongue.     

Experimental porta-caval anastomosis and motor nerve conduction velocity in the rat

Summary The influence of portal-systemic shunting on maximal motor nerve conduction velocity (MCV) was analyzed in rats with portacaval shunts. At 3 and 8 weeks after the shunting there was a marked but transient fall in MCV. This was not prevented by colectomy. At 16 weeks the MCV had almost normalized, despite sustained portal-systemic shunting. When examined at 3 weeks postoperatively, MCV was less affected by ischaemia than in control animals. The results favour hepatocellular failure as the more important pathophysiological mechanism in hepatic neuropathy.     

Poor growth of Mammalian motor and sensory axons into intact proximal nerve stumps

Wallerian degeneration is very slow in the mouse strain now known as C57BL/Ola. Sensory axon regrowth following peripheral nerve lesions is very poor in these animals but motor axons succeed in reinnervating the distal nerve stump even while the majority of severed axons are still intact (Lunn et al., Eur. J. Neurosci., 1, 27 - 33, 1989). To see if motor axons could grow into a completely undegenerated portion of nerve, the proximal stumps of the peroneal and tibial nerves were sutured together in six BALB/c mice and the ability of large motor and sensory fibres from the tibial nerve to grow into the peroneal nerve was examined electrophysiologically in four of them. For the acute experiment the peroneal nerve was cut approximately 7 mm central to the point of suture to the tibial nerve. Both at 2 weeks and 7 weeks after surgery the size of the potential recorded in the ventral roots on stimulating the portion of peroneal nerve into which tibial axons were directed to grow was only approximately 8% of the potential recorded when the tibial nerve was itself stimulated. The potential recorded in the dorsal roots was only approximately 2%. Counts of axon numbers in electron micrographs showed a small but non-significant increase over normal in the number of unmyelinated axons in the peroneal nerves which had been connected to the tibial nerve in this way. It is concluded, in agreement with Langley and Anderson (J. Physiol., 31, 365 - 391, 1904), that axon growth into intact nerves is extremely limited in mammals and that the distal nerve stump of C57BL/Ola mice, although it degenerates very slowly, is not therefore equivalent to an intact peripheral nerve.     

Collateral sprouting of sensory axons after end-to-side nerve coaptation--a longitudinal study in the rat

The end-to-side nerve coaptation is able to induce collateral sprouting of axons from the donor nerve and to provide functional reinnervation of the target tissue. Sensory axon sprouting and its effects on the donor nerve up to 9 months after the end-to-side nerve coaptation were studied in the rat. Peroneal, tibial and saphenous nerves were transected and ligated, and the distal stump of the transected peroneal nerve was sutured to the side of the uninjured sural nerve. The average skin area of the residual sensitivity to pinch due to the axons sprouting through the recipient peroneal nerve did not change statistically significantly between 4 and 9 months after surgery. Axon counting, measurements of compound action potentials and retrograde neuron labeling indicate that the sprouting of the myelinated sensory axons and unmyelinated axons through the recipient nerve was largely completed by 2 months and 4 months after the end-to-side nerve coaptation, respectively, and remained stable thereafter for at least 9 months. A decrease in the amplitude and area of the CAP of myelinated fibers, observed in the donor nerve up to 4 months after surgery, was probably due to mild degeneration of nerve fibers and a tendency of the diameter of myelinated axons to decline. However, no significant changes in functional, electrophysiological or morphological properties of the donor nerve could be observed at the end of the observational period, indicating that end-to-side nerve coaptation has no detrimental effect on the donor nerve on a long-term scale.     

Martin–Gruber anastomosis with anomalous superficial radial innervation to ulnar dorsum of hand: A pitfall when common variants coexist

The Martin–Gruber anastomosis (MGA) is the most common anatomic variation in the upper extremity. Anomalous superficial radial innervation to the ulnar dorsum of the hand is the most common cause of an absent dorsal ulnar cutaneous (DUC) response. The coexistence of these variants introduces a relatively common yet underrecognized potential pitfall in nerve conduction studies (NCS). We performed confirmatory NCS in two cases referred for ulnar neuropathy in the forearm (case 1) and at the elbow (UNE, case 2). Initial NCS in both cases suggested ulnar nerve injury at the forearm and elbow, respectively, based on an apparent conduction block in ulnar motor fibers in the forearm (case 1) and elbow (case 2), and absent DUC responses. Additional NCS documented an MGA in the mid‐forearm (case 1) and high proximal forearm (case 2) with anomalous superficial radial innervation to the ulnar dorsum of the hand (both cases). Failure to recognize the coexistence of these two common variants may lead to misdiagnosis of ulnar neuropathy and inappropriate treatment. Muscle Nerve, 2009     

Synaptic remodeling in the dorsal motor nucleus of the vagus nerve following vagal-hypoglossal nerve anastomosis in the cat

Horseradish peroxidase (HRP) retrograde tracing techniques and morphometric analyses were performed to investigate synaptic remodeling associated with neuronal and glial changes in the dorsal motor nucleus of the vagus (DMV) of cats after vagal-hypoglossal nerve anastomosis (VHA). At 25 days postoperation (dpo), in the early target-reinnervation stage, there were 50% fewer presynaptic boutons containing round vesicles (R) or round and large dense-cored synaptic vesicles (R+D) contacting HRP-labeled DMV motoneurons. The loss of R boutons was maintained throughout the remaining postoperative intervals up to 500 dpo, whereas R+D boutons were further reduced at 123 dpo but were restored at 315 dpo, so that, by 500 dpo, 71.4% of them had gained access to the DMV motoneurons. Boutons containing pleomorphic synaptic vesicles (P) were completely disconnected from the DMV motoneurons at 25 dpo and did not reappear even in the long-term reinnervation stage. Loss and recovery of presynaptic boutons occurred in parallel with changes in astroglial ensheathment of the DMV motoneurons. It is suggested that synaptic remodeling associated with astroglial ensheathment in the DMV may be influenced by some retrogradely transported factors/signals derived from the newly acquired target organ, viz. tongue skeletal musculature. Our results further suggest that the observed changes in boutonal configurations may be attributable to modified functions of the DMV motoneurons induced by VHA.     

Median--ulnar nerve communications and anomalous innervation of the intrinsic hand muscles: an electrophysiological study.

One hundred (100) left arms were examined for median-to-ulnar or ulnar-to-median nerve anastomoses using surface electrodes. Muscles innervated by the anastomosis were determined using a concentric needle electrode. We found a motor median-to-ulnar nerve anastomosis in the forearm in 32% of the cases (Martin-Gruber anastomosis, MGA). No case of motor ulnar-to-median nerve anastomosis in the forearm could be found. The MGA mainly innervated muscles, which are normally supplied by the ulnar nerve. The high incidence of MGA in this study shows that all clinically relevant motor median-to-ulnar nerve communications in the forearm can be detected using surface electrodes in routine examinations. Stimulus spread must be looked for and eliminated by the methods described.     

Strain and stress variations in the human amniotic membrane and fresh corpse autologous sciatic nerve anastomosis in a model of sciatic nerve injury

A 10-mm long sciatic nerve injury model was established in fresh normal Chinese patient cadavers. Amniotic membrane was harvested from healthy maternal placentas and was prepared into multilayered,coiled,tubular specimens.Sciatic nerve injury models were respectively anastomosed using the autologous cadaveric sciatic nerve and human amniotic membrane.Tensile test results showed that maximal loading,maximal displacement,maximal stress,and maximal strain of sciatic nerve injury models anastomosed with human amniotic membrane were greater than those in the autologous nerve anastomosis group.The strain-stress curves of the human amniotic membrane and sciatic nerves indicated exponential change at the first phase,which became elastic deformation curves at the second and third phases,and displayed plastic deformation curves at the fourth phase,at which point the specimens lost their bearing capacity.Experimental findings suggested that human amniotic membranes and autologous sciatic nerves exhibit similar stress-strain curves, good elastic properties,and certain strain and stress capabilities in anastomosis of the injured sciatic nerve.     

Apparent conduction block in patients with ulnar neuropathy at the elbow and proximal Martin-Gruber anastomosis

A Martin-Gruber anastomosis (MGA) commonly results in an abnormal decline in amplitude across the forearm segment when ulnar motor nerve conduction studies are performed. A recent report described a proximal MGA resembling partial conduction block in a patient with ulnar neuropathy at the elbow (UNE). As a result, we screened patients with similar findings. We detected a proximal MGA in three patients over a period of 2 years, which suggests that this may be an under-recognized anomaly. We conclude that a proximal MGA must be excluded in all cases of UNE showing apparent partial conduction block across the elbow segment.     

Trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae: evidence for continual axon generation and presence of exceptionally small myelinated axons

Cross sections from the trigeminal alveolar nerve of the lower jaw in the cichlid Tilapia mariae were examined by electron microscopy. The nerve fibers are arranged in groups with a core of unmyelinated and small myelinated axons, surrounded by myelinated axons of varying sizes. The core contains large bundles of unmyelinated axons collectively ensheathed by circumferentially located Schwann cells, as well as smaller bundles of unmyelinated axons partly separated from each other by Schwann cell processes. Among the unmyelinated axons, occasional scattered profiles resembling growth cones are seen. The total number of axons in this tooth-related nerve increases from approximately 1,500 to 5,000, as the animals grow in length from 4.5 to 21.5 cm. Some 24-49% of the axons are unmyelinated. The myelinated axons have maximum diameters of 1.0-3.0 micron, depending on body size. Most myelinated axons have diameters less than 1.0 micron and the smallest ones reach down to 0.3 micron. These results show that there is a continual addition of axons to the alveolar nerve of the lower jaw in Tilapia mariae and that the critical diameter for myelination in this peripheral nerve is similar to that typically found in the mammalian CNS.