Functional and morphological evaluation of the trapezius muscle after spinal accessory nerve transfer to brachial plexus nerves.

INTRODUCTION: The main innervation of the trapezius muscle is provided by the spinal accessory nerve. Several studies describe the contributions of cervical plexus roots to the trapezius muscle innervation, either directly or through connections with the spinal accessory nerve. There is no adequate understanding of how the trapezius muscle is affected after using the spinal accessory nerve in nerve transfer procedures with the usual technique, preserving at least 1 branch for the upper trapezius. METHODS: We evaluated 20 patients with sequelae of traumatic brachial plexus injury who underwent surgical procedures for brachial plexus repair or free muscle transfer, which included the spinal accessory nerve transfer technique and were followed for a minimum of 1 year. The three portions trapezius muscle were evaluated by physical examination, magnetic resonance imaging (analysis of fatty degeneration) and electromyography. RESULTS: In all evaluation methods, the middle and lower portions of the trapezius muscle showed more significant morphological and/or functional impairment than the upper portion, in most cases. There was a statistically significant difference in all the complementary exams results, between the affected side (with sacrifice of the nerve) versus the normal side, in the middle and lower portions of the trapezius muscle. CONCLUSIONS: Physical examination alone is not sufficient to determine the residual functionality of the trapezius muscle. Magnetic resonance imaging and electromyography are useful tools to assess both morphological involvement of the trapezius muscle and nerve conduction impairment of the trapezius muscle, respectively. The results suggest that the middle and lower portions of the trapezius muscle are affected by previous SAN transfer and should be considered with caution for further muscle transfer procedures.

Invasive occipital nerve stimulation for refractory chronic cluster headache: what evolution at long-term? Strengths and weaknesses of the method.

BACKGROUND: Invasive Occipital Nerve Stimulation (iONS) is a costly technique which appears effective in drug-refractory chronic cluster headache (drCCH) management. Available data on long-term effectiveness and safety of iONS in this indication are scarce, though they could be useful to neurologists and patients in daily practice. The purpose of this short report is to discuss the very long-term outcome of a drCCH cohort, including adverse events. FINDINGS: Previously, favourable results were obtained with iONS in 15 drCCH patients: 80 % were significantly improved and 60 % were pain free. We report here the very long-term follow-up (up to nine years) of 10 patients belonging to this cohort. Meanwhile 5 patients had to be definitively explanted because of device infection (3) or paresthesia intolerance (2). Four patients (40 %) evolved to an episodic form of CH. Six remained chronic but their attack frequency was decreased by 70 % on average. Intake of preventive drugs is still necessary in 80 % of patients. All patients needed at least one battery replacement. CONCLUSIONS: Up to nine years after implantation, iONS is still effective in most patients with drCCH. Concomitant preventive drugs remain often necessary. Forty percent of patients reverse to episodic CH, possibly by natural history. iONS is not a benign procedure but device-related complications appear similar to those reported with other invasive neurostimulators.

Motor innervation of the trapezius muscle: Intraoperative motor conduction study during neck dissection.

OBJECTIVES: To evaluate the motor input from the spinal accessory nerve (SAN) and the branches of the cervical plexus in an intraoperative motor nerve conduction study measuring motor action potentials by direct stimulation of the exposed nerve during neck dissection. METHODS: The entire length of the SAN and the contributions from the upper cervical plexus were preserved. Compound muscle action potentials were measured for each part of the trapezius muscle on stimulation of the SAN, C2, C3, and C4 nerves. RESULTS: With stimulation of the spinal nerve, evoked responses were obtained from all 24 patients in the descending, transverse, and ascending trapezius muscle. C2 contributions were noted in 2 out of 24 patients; however, no patient revealed responses in all three parts of the muscle. C3 contributions were seen in 11 out of 24 patients, supplying all three parts of the muscle in 8 patients, and C4 contributions were noted in 20 out of 24 patients, supplying all three parts of the muscle in 16 of them. CONCLUSIONS: The SAN provided the most consistent motor input to the trapezius muscle. The C2, C3, and C4 nerves also provided motor input to the trapezius muscle; however, they were either inconsistently present or, when present, irregularly innervated the three parts of the trapezius muscle.

[Tongue reconstruction with a bilateral infrahyoid flap innervated by Ansa Cervicalis after total glossectomy]. / Le lambeau infrahyoïdien bilatéral innervé par l'Ansa Cervicalis pour la reconstruction des glossectomies totales.

INTRODUCTION: Reconstruction after total glossectomy remains a functional challenge. It must provide a large volume to ensure adequate phonation and swallowing. We present the larynx sparing bilateral infrahyoid flap reconstruction procedure after total glossectomy. PATIENTS AND METHOD: Three patients managed for an epidermoid carcinoma of the tongue, classified T4N0, underwent total glossectomy. The tongue was reconstructed with a bilateral infrahyoid flap pedicled on two superior thyroid arteries and innervated by Ansa Cervicalis. RESULTS: Oral food intake was resumed after 8 to 20 days. No false route was observed. The muscular flap mobility was clinically satisfactory. It was assessed by EMG in one case. Esophageal transit confirmed the absence of stasis and false route for one patient. DISCUSSION: This short series proves the feasibility of bilateral innervated and pedicled infrahyoid flap procedure. It is an alternative to volumetric and functional reconstruction after total glossectomy. The indications are rare and restricted to patients without IIa nodal region invasion. Our results are still limited and need to be confirmed by a larger series and by a more systematic assessment.

A Review of the History, Anatomy, and Development of the C1 Spinal Nerve.

The C1 spinal nerve is a fascinating anatomic structure owing to its wide range of variations. Throughout history, understanding of the cranial and spinal nerves has probably influenced the current conception of this nerve among anatomists. Located at the craniocervical junction, the C1 spinal nerve contributes to the motor innervation of deep cervical muscles through the cervical (anterior) and Cruveilhier's (posterior) plexuses. Sensory functions of this nerve are more enigmatic; despite investigations into its dorsal rootlets, a dorsal root ganglion, and the relationships between this nerve and adjacent cranial and spinal nerves, there is still no consensus regarding its true anatomy. In this article, we review the available literature and discuss some of the developmental models that could potentially explain the wide range of variations and functions of the C1 nerve.

Pineal N-acetyltransferase activity: effect of sympathetic stimulation.

Stimulation of preganglionic sympathetic fibers to the superior cervical ganglia elevates the activity of pineal N-acetyltransferase. After the stimulation-induced rise in enzyme activity, a return toward baseline levels occurs whether or not nerve stimulation is continued. The ability of pineal N-acetyltransferase activity to fall in the presence of stimulation may account for the persistence of its rhythm in blinded animals.

Modulatory effects of somatosensory electrical stimulation on neural activity of the dorsal cochlear nucleus of hamsters.

The effects of somatosensory electrical stimulation on the dorsal cochlear nucleus (DCN) activity of control and tone-exposed hamsters were investigated. One to three weeks after sound exposure and control treatment, multiunit activity was recorded at the surface of the left DCN before, during, and after electrical stimulation of the basal part of the left pinna. The results demonstrated that sound exposure induced hyperactivity in the DCN. In response to electrical stimulation, neural activity in the DCN of both control and exposed animals manifested four response types: S-S, suppression occurring during and after stimulation; E-S, excitation occurring during stimulation and suppression after; S-E, suppression occurring during stimulation and excitation after; and E-E, excitation occurring during and after stimulation. The results showed that there was a higher incidence of suppressive (up to 70%) than of excitatory responses during and after stimulation in both groups. In addition, there was a significantly higher degree of suppression after, rather than during stimulation. At high levels of electrical current, the degree of the induced suppression was generally higher during and after stimulation in exposed animals than in controls. The similarity of our results to those of previous clinical studies further supports the view that DCN hyperactivity is a direct neural correlate of tinnitus and that somatosensory electrical stimulation can be used to modulate DCN hyperactivity. Optimization of stimulation strategy through activating only certain neural pathways and applying appropriate stimulation parameters may allow somatosensory electrical stimulation to be used as an effective tool for tinnitus suppression.

Nerve fiber analysis of ansa cervicalis-vagus communications.

Communications between the ansa cervicalis and the vagus nerve, although described only as variations in many textbooks, can be observed frequently in the dissection room. Following macroscopic observation, some of such cases were subsequently dissected under surgical microscope to determine the nature of such communications. As a result, two broad categories of communications between the ansa cervicalis complex and the vagus nerve could be recognized: (i) false (pseudo) communications, where the two nerves were attached only by the connective tissue with no fiber exchange; and (ii) true communications, with nerve fiber involvement. Fiber analysis showed that the majority of the ansa-vagal communications observed during gross dissection were of the first category. True communications, when present, were only scanty contributions and always directed towards the side of the vagus. In addition, the vagus (region of the inferior ganglion) and hypoglossal nerves were found to be in close contact at the base of the skull and usually could not be separated by gross dissection. But such attachments, too, were shown to be almost entirely of false nature except for the possible presence of a few fine nerve filaments. It seems that the ansa-vagal communications are merely a result of the close physical relationship between the two structures and serve no significant functional purpose, but at the same time may hinder the prospects of using ansa cervicalis in surgical procedures such as re-innervation of laryngeal and facial muscles, following damage to recurrent laryngeal and facial nerves, respectively.

Does bilateral superficial cervical plexus block decrease analgesic requirement after thyroid surgery?

In this randomized, double-blind and controlled study we evaluated and compared the analgesic efficacy of bilateral superficial cervical plexus block and local anesthetic wound infiltration after thyroid surgery. Forty-five patients were assigned to 3 groups. After general anesthesia induction, bilateral superficial cervical plexus block with 0.25% bupivacaine 15 mL in each side was performed in Group I, and local anesthetic wound infiltration with 0.25% bupivacaine 20 mL was performed in Group II. In Group III (control) no regional block was administered. Intravenous patient-controlled analgesia was used to evaluate postoperative analgesic requirement. Neither visual analog scale scores nor total patient-controlled analgesia doses were different among groups. We concluded that bilateral superficial cervical plexus block or local anesthetic wound infiltration with 0.25% bupivacaine did not decrease analgesic requirement after thyroid surgery.

Innervation of the trapezius muscle: is cervical contribution important to its function?

OBJECTIVE: To study the effect of the cervical plexus and the accessory nerve to the function of the trapezius muscle. STUDY DESIGN AND SETTING: Eighteen adult male Sprague-Dawley rats were randomly divided into three groups. The neurotomies were performed in the left sides and the right sides served as within-subject controls. In group A, the accessory nerve was transected. The C2-5 were transected in group B, and both of the accessory nerve and C2-5 were cut in group C. The electrophysiologic, myophysiologic, and histologic changes of the muscles were measured. RESULTS: There were significant differences (P < 0.05) between the three groups in the recovery rates of the transverse area of the muscles. The CMAP recorded from the experimental sides in group B were similar to the control sides. The values of the maximum tension of the tetanus contraction between the two sides showed no differences either (P > 0.05). CONCLUSION: The accessory nerve supplies the most important motor input to the trapezius. Motor innervations of the cervical plexus are not very significant.

Superficial vs combined cervical plexus block for carotid endarterectomy: a prospective, randomized study.

BACKGROUND: The present study compares combined and superficial cervical plexus block in patients submitted to carotid endarterectomy (CEA) in terms of anesthetic efficacy, satisfaction of the patient and surgeon, complications resulting from the type of anesthesia, and final outcome. METHODS: A total of 125 patients submitted to elective CEA were randomized into 2 groups: the first group was submitted to superficial cervical block and the second group to combined (superficial plus deep) cervical block. RESULTS: No significant difference in anesthetic quality was observed between the 2 types of blocks. Complications related to the anesthetic method were observed in only 1 (1.6%) patient of the superficial block group and in 5 (7.4%) patients of the combined block group (P > .05). Anesthetic supplementation by the surgeon was necessary in 50 (81.96%) patients, with no significant difference between the 2 groups. The surgical conditions were closely similar in the 2 groups, showing no significant difference. The final morbidity and mortality in the present series was 1.6%. CONCLUSIONS: Superficial cervical anesthetic block shows the same efficacy as combined block, with the surgical conditions being closely similar. The incidence of complications related to the anesthetic technique is higher for combined block. The type of block does not influence the final outcome of the patients.

Changes in (3H)leucine incorporation into pineal proteins following estradiol or testosterone administration: involvement of the sympathetic superior cervical ganglion.

Pineal denervation by superior cervical ganglionectomy (Gx) decreased high affinity binding of estradiol (E2) to the pineal cytosol of female rats and of testosterone to the cytosol of male rats by 40 and 26% and by 75 and 80%, 5 and 14 days after sugery; hormone binding remained unchanged up to 24 h after surgery. Binding to the nuclear fraction decreased sigificantly by 2 weeks after incorporation of (3H) leucine into pineal proteins in Gx. A single injection of E2 (mug) to testosterone propionate (TP) (500 mug) failed to increase the Gx rats when injected 1 or 5 days after surgery. Significant increases were observed in sham-operated controls or in rats subjected to bilateral decentralization of ganglia; however on the 5th day an impairment was observed in hormone ability to enhance [3H]leucine incorporation in decentralized rats. The administration of isoproterenol 19 and 3 h before sacrifice replenished pineal-binding sites for E2 and testosterone in Gx rats, but failed to restore the responsiveness of denervated pineals to hormone administration. Moreover, E2 or TP treatment blocked the increase in labeled amino acid incorporation into proteins brought about by isoproterenol per se. The administration of propranolol 2 and 7 h after hormone injection decreased the ability of E2 and TP to enhance [3H]leucine incorporation by 55 and 41%, respectively. Tyrosine hydroxylase activity of the superior cervical ganglia decreased by 36 and 41% 6 h after E2 or TP administration, and by 43 and 47% after 3 daily injections of the hormones, whereas pineal tyrosine hydroxylase remained unchanged. Hormone treatment for 3 days increased the in vitro uptake of norepinephrine by the ganglia but did not affect uptake in the pineal gland. These data indicate that the integrity of neurons of the superior cervical ganglia is an absolute requirement for E2 and testosterone to enhance [3H]leucine incorporation into pineal proteins in rats.

Localization of sympathetic postganglionic neurons of physiologically identified cardiac nerves in the dog.

Cardiac nerves were identified physiologically and injected with horseradish peroxidase in 38 dogs. Retrogradely labeled neurons were present in the greatest number in the middle cervical ganglion, whereas fewer labeled neurons were present in the stellate ganglion. Only occasional neurons in the superior cervical ganglion were labeled, and no labelphysiologically and injected with horseradish peroxidase in 38 dogs. Retrogradely labeled neurons were present in the greatest number in the middle cervical ganglion, whereas fewer labeled neurons were present in the stellate ganglion. Only occasional neurons in the superior cervical ganglion were labeled, and no labelphysiologically and injected with horseradish peroxidase in 38 dogs. Retrogradely labeled neurons were present in the greatest number in the middle cervical ganglion, whereas fewer labeled neurons were present in the stellate ganglion. Only occasional neurons in the superior cervical ganglion were labeled, and no labeled cells were found in the T3 to T6 paravertebral ganglia or in the ganglia contralateral to the nerve injected. following injections into specific cardiac nerves, retrograde labeling was widespread within the middle cervical ganglion, and the distributions of labeled neurons from different nerves overlapped considerably. In the middle cervical ganglion there was little or no regional grouping of cells projecting to specific cardiac nerves. within the stellate ganglion, however, te cardiac-sympathetic cells were clustered primarily at the cranial pole near toe origin of the ventral and dorsal ansae. Mediastinal ganglia and ganglia located in cardiac nerves were frequently as heavily labeled as the ipsilateral stellate ganglion. The occurrence of heavy labeling in mediastinal and cardiac nerve ganglia indicates that these hitherto unreported ganglia play a significant role in cardiac neural regulation. These data imply that the organization of sympathetic neurons controlling the heart is much more complex than has previously been considered.

Effects of vagal afferent stimulation on cervical spinothalamic tract neurons in monkeys.

The purpose of this study was to determine if electrical stimulation of vagal afferents inhibited activity of primate spinothalamic tract (STT) neurons located in cervical segments of the spinal cord. Previous studies show vagal inhibition of STT neurons in more caudal segments of the cord, which receive visceral spinal inputs and somatic inputs from proximal body regions. We hypothesized that activation of vagal afferents would inhibit cervical STT neurons that were excited by cardiopulmonary sympathetic afferents and not inhibit those cells inhibited or unaffected by this visceral input. Because visceral pain is referred to proximal somatic fields, we also hypothesized that STT neurons with excitatory somatic fields confined to distal areas would not be inhibited by vagal stimulation. In 42 cervical STT neurons, we found no difference in effects of vagal stimulation between cells excited or not excited by stimulation of cardiopulmonary sympathetic afferents. Responses to vagal stimulation also were the same for cervical STT cells with proximal or distal somatic fields. Furthermore, there was no difference in the inhibitory effects of vagal stimulation in cervical as compared to thoracic STT neurons. We concluded that vagal afferent stimulation causes a general inhibitory effect at all levels of the spinal cord on neurons which transmit nociceptive information.

Localization of substance P-like immunoreactivity in nerves in the tooth pulp.

The occurrence of substance P (SP)-like immunoreactivity was studied in dental pulps of the cat. In untreated animals SP-positive fibres were found in all areas of the pulp. Most fibres were seen in central parts of the pulp but they were also observed in relation to the odontoblasts. Single, possibly unmyelinated, or fine caliber fibres or small bundles of them were seen running close to large non-fluorescent myelinated nerves, to blood vessels or without any obvious association with either of these structures. Fourteen days after transection of the inferior alveolar nerve no SP-positive fibres were observed in pulps on the denervated side. Transection of the cervical sympathetic ganglion did not change the occurrence of SP-positive fibres. The results indicate the existence of at least two types of afferent fibres in the dental pulp of the cat. Since the tooth pulp has been demonstrated to give rise only to pain sensation when stimulated, the results give morphological support for a role of SP neurones in pain transmission.

Fine structure of sensory nerves in the rat cornea: an experimental nerve degeneration study.

Fine structure of nerve fibres and terminals in the rat cornea was studied after fixation with glutaraldehyde and osmium tetroxide or with potassium permanganate. Superior cervical and/or ciliary ganglionectomy as well as ophthalmic neurotomy were performed in order to verify the origin of the corneal nerves. In the control corneas axon profiles with granular vesicles were observed in the stroma. Other axons containing agranular vesicles were found both in the stroma and in the epithelium. Superior cervical ganglionectomy abolished only the axons containing granular vesicles but did not affect the corneal blink reflex. Ciliary ganglionectomy induced more conspicuous changes in both stromal and intraepithelial axon profiles. The corneal reflex was, however, normal. Some of the axons containing agranular vesicles also showed degenerative changes. However, intact axon profiles with agranular vesicles were seen even after extirpation of both the ciliary ganglion and the superior cervical ganglion (combined autonomic ganglionectomy). On the other hand, all axon profiles with agranular vesicles disappeared after coagulation of the ophthalmic and maxillary nerves (sensory denervation). This operation destroyed most of the axons in all parts of the cornea and abolished the blink reflex. It is concluded that the axon profiles in the corneal epithelium, containing agranular vesicles, are sensory axons of the trigeminal nerve. A possible role of the vesicles in sensory nerves is discussed.

Stimulation of the cervical sympathetic nerves increases intraocular pressure.

PURPOSE: To test the hypothesis that a moderate electrical stimulation of the cervical sympathetic nerves in rabbits can increase intraocular pressure (IOP). METHODS: Electrical stimulations of the cervical sympathetic nerves were performed in anesthetized and conscious rabbits. Intraocular pressure, pupil size, and concentrations of aqueous humor components were monitored. RESULTS: In urethane-anesthetized rabbits, stimulations of 5 V and 1 ms at 2.5 Hz for 1 hr and then at 20 Hz for 2 hr caused a short inhibition of IOP decrease and a prolonged mydriasis. Concentrations of norepinephrine (NE), neuropeptide Y (NPY), and cyclic AMP (cAMP) in aqueous humor were elevated. Aqueous humor protein concentration was not changed. In rabbits anesthetized with ketamine, chlorpromazine, and pentobarbital, electrical stimulations with the same parameters caused prolonged increases in IOP and pupil size. Aqueous humor NE and cAMP concentrations increased, while NPY and protein concentrations did not change. When the stimulations were set at 5 Hz for 3 hr under this anesthesia, the increase of IOP and mydriasis persisted. However, only the NE concentration increased. In conscious rabbits, stimulations of 5 V and 1 ms at either 5 Hz or 20 Hz were delivered from a portable stimulator for 4 hr, starting 2 hr before the onset of the dark. Stimulations at 5 Hz caused an increase in IOP in the light phase. The circadian IOP elevation in the dark phase persisted. When 20 Hz was used, a transient fall in IOP was observed, and the circadian IOP elevation was eliminated. Aqueous humor NE concentration doubled in conscious rabbits receiving electrical stimulations at 5 Hz for 1 hr. CONCLUSIONS: A moderate electrical stimulation of the cervical sympathetic nerves can increase IOP in anesthetized rabbits and in conscious rabbits in the light phase.

Differential ovulatory responses of the right and left ovaries of the adult rat to unilateral lesion and anaesthesia of the cervico-vaginal plexus.

Differences were observed in the ovulation rates of the right and left ovaries in response to unilateral lesions of the cervico-vaginal plexus (CVP) followed by pseudopregnancy or by anaesthesia of the CVP induced with panthocaine plus adrenaline (right ovary 6.7 +/- 0.4 (S.E.M.) vs left ovary 4.6 +/- 0.9; P less than 0.05). Pseudopregnancy (days showing a dioestrous smear after copulation with a vasectomized male before an oestrous smear following a pro-oestrous one) lasted longer in rats with a lesion in the CVP than in a control pseudopregnant group (14.9 +/- 0.5 vs 11.2 +/- 0.5; P less than 0.01). Anaesthesia of the CVP performed on each day of the oestrous cycle did not modify the ovulation rate compared with laparotomized animals. Both laparotomy and anaesthesia of the CVP performed on oestrus or day 1 of dioestrus blocked ovulation but when they were performed on day 2 of dioestrus or pro-oestrus they failed to do so (laparotomy 9/18 vs 12/14, P less than 0.05; anaesthesia of CVP 3/11 vs 17/17, P less than 0.05). The number of ova shed by the left ovary in animals with anaesthetized CVP was lower than by the right ovary (4.5 +/- 0.6 vs 6.2 +/- 0.5; P less than 0.05). These results add further support to the idea that the CVP participates in the regulation of ovulation rate, and that the left ovary is less adaptable than the right when innervation is challenged.

Sonographic mapping of the normal brachial plexus.

BACKGROUND AND PURPOSE: Mapping of the brachial plexus with MR imaging has been reported and may have potential clinical applications (eg, precise localization of traumatic or tumoral nerve lesions, selective anesthesia of the brachial plexus). We sought to demonstrate that mapping of the brachial plexus may be performed by means of sonography. METHODS: Twelve healthy adult volunteers (seven women and five men; age range, 24-38 years; mean, 31 years) underwent bilateral sonographic examination for the assessment of the nerve structures of the brachial plexus from the extraforaminal part to the axillary part. Four formolated cadavers (two male and two female; age range, 66-84 years; mean, 77.5 years) were frozen and sawed into 3-mm-thick contiguous sections in the same plane as that used for the sonographic exploration. RESULTS: A satisfactory sonographic examination was performed in 10 of 12 volunteers, leading to a good association with anatomic sections. Two volunteers were excluded from the study because a clear depiction of the brachial plexus was difficult owing to a short neck and low echogenicity at examination. The association between sonographic images and anatomic sections allowed us to map the brachial plexus. The subclavian and deep cervical arteries were useful landmarks for this mapping. The eighth cervical nerve root and the first thoracic nerve root were the most difficult part of the brachial plexus to depict because of their deep location. CONCLUSION: The brachial plexus can be mapped with sonography. However, this technique requires a good grounding in anatomy and may be impossible in short-necked individuals.