Comparison of botulinum toxin serotypes A and B for the treatment of cervical dystonia

OBJECTIVE

To directly compare two serotypes of botulinum toxin (BoNTA and BoNTB) in cervical dystonia (CD) using a randomized, double-blind, parallel-arm study design.

METHODS

Subjects with CD who had a previous response from BoNTA were randomly assigned to BoNTA or BoNTB and evaluated in a blinded fashion at baseline, 4 weeks, 8 weeks, and 2-week intervals thereafter until loss of 80% of clinical effect or completion of 20 weeks of observation. CD severity was measured with the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS), and adverse events were assessed by structured interview. Statistical analysis included Wilcoxon rank sum test, log rank tests, and Kaplan-Meier survival curves for duration of effect.

RESULTS

A total of 139 subjects (BoNTA, n = 74; BoNTB, n = 65) were randomized at 19 study sites. Improvement in TWSTRS score was found at 4 weeks after injection and did not differ between serotypes. Dysphagia and dry mouth were more frequent with BoNTB (dysphagia: BoNTA 19% vs BoNTB 48%, p = 0.0005; dry mouth (BoNTA 41% vs BoNTB 80%, p < 0.0001). In clinical responders, BoNT A had a modestly longer duration of benefit (BoNTA 14 weeks, BoNTB 12.1 weeks, p = 0.033).

CONCLUSION

Both serotypes of botulinum toxin (BoNTA and BoNTB) had equivalent benefit in subjects with cervical dystonia at 4 weeks. BoNTA had fewer adverse events and a marginally longer duration of effect in subjects showing a clinical response.

Variables contributing to the coordination of rapid eye/head gaze shifts

In this article results of several published studies are synthesized in order to address the neural system for the determination of eye and head movement amplitudes of horizontal eye/head gaze shifts with arbitrary initial head and eye positions. Target position, initial head position, and initial eye position span the space of physical parameters for a planned eye/head gaze saccade. The principal result is that a functional mechanism for determining the amplitudes of the component eye and head movements must use the entire space of variables. Moreover, it is shown that amplitudes cannot be determined additively by summing contributions from single variables. Many earlier models calculate amplitudes as a function of one or two variables and/or restrict consideration to best-fit linear formulae. Our analysis systematically eliminates such models as candidates for a system that can generate appropriate movements for all possible initial conditions. The results of this study are stated in terms of properties of the response system. Certain axiom sets for the intrinsic organization of the response system obey these properties. We briefly provide one example of such an axiomatic model. The results presented in this article help to characterize the actual neural system for the control of rapid eye/head gaze shifts by showing that, in order to account for behavioral data, certain physical quantities must be represented in and used by the neural system. Our theoretical analysis generates predictions and identifies gaps in the data. We suggest needed experiments.

An endurance-strength training regime is effective in reducing myoelectric manifestations of cervical flexor muscle fatigue in females with chronic neck pain

OBJECTIVE

The purpose of this study was to investigate whether an endurance-strength training program is effective in reducing myoelectric manifestations of sternocleidomastoid (SCM) and anterior scalene (AS) muscle fatigue which have been found to be greater in people with chronic neck pain.

METHODS

Fifty-eight female patients with chronic non-severe neck pain were randomized into one of two 6-week exercise intervention groups: an endurance-strength training regime for the cervical flexor muscles or a referent exercise intervention involving low load retraining of the cranio-cervical flexor muscles. The primary outcomes were a change in maximum voluntary contraction (MVC) force and change of the initial value and rate of change of the mean frequency, average rectified value and conduction velocity detected from the SCM and AS muscles during sub-maximal isometric cervical flexion contractions at 50, 25 and 10% MVC.

RESULTS

At the 7th week follow-up assessment, the endurance-strength training group revealed a significant increase in MVC force and a reduction in the estimates of the initial value and rate of change of the mean frequency for both the SCM and AS muscles (P<0.05). Both exercise groups reported a reduced average intensity of neck pain and reduced neck disability index score (P<0.05).

CONCLUSIONS

An endurance-strength exercise regime for the cervical flexor muscles is effective in reducing myoelectric manifestations of superficial cervical flexor muscle fatigue as well as increasing cervical flexion strength in a group of patients with chronic non-severe neck pain.

SIGNIFICANCE

Provision of load to challenge the neck flexor muscles is required to reduce the fatigability of the SCM and AS muscles in people with neck pain. Improvements in cervical muscle strength and reduced fatigability may be responsible for the reported efficacy with this type of exercise program.

Improved Technique for Harvesting the Accessory Nerve for Transfer in Brachial Plexus Injuries

Objective:

The accessory nerve is frequently used as a donor for nerve transfer in brachial plexus injuries. In currently available techniques, nerve identification and dissection is difficult because fat tissue, lymphatic vessels, and blood vessels surround the nerve. We propose a technique for location and dissection of the accessory nerve between the deep cervical fascia and the trapezius muscle.

Methods:

Twenty-eight patients with brachial plexus palsy had the accessory nerve surgically transplanted to the suprascapular nerve. To harvest the accessory nerve, the anterior border of the trapezius muscle was located 2 to 3 cm above the clavicle. The fascia over the trapezius muscle was incised and detached from the anterior surface of the muscle, initially, close to the clavicle, then proximally. The trapezius muscle was detached from the clavicle for 3 to 4 cm. The accessory nerve and its branches entering the trapezius muscle were identified. The accessory nerve was sectioned as distally as possible. To allow for accessory nerve mobilization, one or two proximal branches to the trapezius muscle were cut. The most proximal branch was always identified and preserved. A tunnel was created in the detached fascia, and the accessory nerve was passed through this tunnel to the brachial plexus.

Results:

In all of the cases, the accessory nerve was easily identified under direct vision, without the use of electric stimulation. Direct coaptation of the accessory nerve with the suprascapular nerve was possible in all patients.

Conclusion:

The technique proposed here for harvesting the accessory nerve for transfer made its identification and dissection easier.

Eye movements cannot explain vibration-induced visual motion and motion aftereffect

Eye movements are thought to account for a number of visual motion illusions involving stationary objects presented against a featureless background or apparent motion of the whole visual field. We tested two different versions of the eye movement account: (a) the retinal slip explanation and (b) the nystagmus-suppression explanation, in particular their ability to account for visual motion experienced during vibration of the neck muscles, and for the visual motion aftereffect following vibration. We vibrated the neck (ventral sternocleidomastoid muscles, bilaterally, or right dorsal muscles) and measured eye movements in conjunction with perceived illusory displacement of an LED presented in complete darkness (N=10). To test the retinal-slip explanation, we compared the direction of slow eye movements to the direction of illusory motion of the visual target. To test the suppression explanation, we estimated the direction of suppressed slow-phase eye movements and compared it to the direction of illusory motion. Two main findings show that neither actual nor suppressed eye movements cause the illusory motion and motion aftereffect. Firstly, eye movements do not reverse direction when the illusory motion reverses after vibration stops. Secondly, there are large individual differences with regards to the direction of eye movements in observers who all experience a similar visual illusion. We conclude that, rather than eye movements, a more global spatial constancy mechanism that takes into account head movement is responsible for the illusion. The results also argue against the notion of a single central signal that determines both perceptual experience and oculomotor behaviour.

Effects of distance and gaze position on postural stability in young and old subjects

Visual stabilization of posture is known to improve when the distance to target fixation decreases; this is attributed to increased angular size of retinal slip induced by body sway. At near distance, however, the eyes converge and efferent or afferent oculomotor signals could also be involved in posture stabilization. The goal of this study is to test whether the distance effect exists for both young and elderly and to test the role of vergence itself and of gaze position. Eighteen young (25.3 years) and 17 elderly (61.6 years) subjects were asked to fixate a target in quiet stance presented either at close (40 cm) or at far distance (200 cm); the vergence angle was 9 degrees and 2 degrees , respectively. For each distance, three gaze positions were studied straight-ahead (0 degrees ), 15 degrees up or down. We found a decrease in the surface of center of pressure (CoP), of standard deviation of antero-posterior and lateral body sway and of speed variance at near distance that occurs for both young and elderly. At far distance, the surface of CoP is smaller for 15 degrees up or down gaze in comparison with straight-ahead position, but at near distance there is no such gaze position effect. In an additional experiment, subjects fixated a target at far distance (200 cm) but prisms were used to cause the eyes to converge by an amount similar to that required for 40 cm viewing distance. The use of prisms decreased surface of CoP to values similar to those for natural near viewing distance. The effect of gaze position and of convergence (experiment with prisms) leads us to suggest that in addition to retinal slip, the ocular motor signals and perhaps related neck muscle activity are involved in postural stabilization. Finally, the elderly presented higher speed variance of CoP than the young subjects even though the surface itself was similar to adult values. We suggest that increment of speed variance is the first sign of senescence in postural control.

Upper neck spinal accessory nerve identification during neck dissection

Iatrogenic injury to the spinal accessory nerve (SAN) during neck dissection may result in significant and avoidable morbidity in the form of ’shoulder syndrome’. The authors describe a simple method, based on the anatomy of the sternocleidomastoid muscle (SCM), which allows consistent and rapid identification of the SAN in the upper neck during dissection, thereby facilitating its preservation.

Characteristics and clinical applications of vestibular-evoked myogenic potentials

A recent technique of assessing vestibular function, the vestibular-evoked myogenic potential (VEMP), is an otolith-mediated, short-latency reflex recorded from averaged sternocleidomastoid electromyography in response to intense auditory clicks delivered via headphones. Since their first description 10 years ago, VEMPs are now being used by investigators worldwide, and characteristic changes observed with aging and in a variety of peripheral and central vestibulopathies have been described. Additional methods of evoking VEMPs, which use air- and bone-conducted short-tone bursts, forehead taps, and short-duration transmastoid direct current (DC) stimulation, have been described, and these complement the original technique. Click-evoked VEMPs are attenuated or absent in a proportion of patients with vestibular neuritis, herpes zoster oticus, late Meniere disease, and vestibular schwannomas; their amplitudes are increased and thresholds are pathologically lowered in superior semicircular canal dehiscence presenting with the Tullio phenomenon. VEMPs evoked by clicks and DC are useful when monitoring the efficacy of intratympanic gentamicin therapy used for chemical vestibular ablation. Prolonged p13 and n23 peak latencies and decreased amplitudes have been observed in association with central vestibulopathy. VEMPs evoked by clicks are a robust, reproducible screening test of otolith function. DC stimulation enables differentiation of labyrinthine from retrolabyrinthine lesions; bone-conducted stimuli permit VEMP recording despite conductive hearing loss and deliver a relatively larger vestibular stimulus for a given level of auditory perception.

Rat strain differences in freezing and sleep alterations associated with contextual fear

STUDY OBJECTIVE

To examine rat strain differences in fear responses and subsequent alterations in sleep associated with contextual fear.

DESIGN

Recordings for each strain were obtained of nondisturbed baseline sleep and of sleep after exposure to a novel chamber (handling control). Afterward, the rats were subjected to shock training for 2 sessions (ST1, ST2) and to contextual fear (CF) alone. Percentage time spent in freezing (FT%) was observed during ST1, ST2 and CF exposures. Sleep was recorded for 20 hours (8-hour light and 12-hour dark period) following ST1, ST2 and CF.

SETTING

NA SUBJECTS: The subjects were 2 inbred rat strains (Fischer 344 [F344] and Lewis [LEW] and one outbred rat strain (Wistar [WST]).

INTERVENTIONS

The rats were surgically implanted with electrodes for recording electroencephalogram and electromyogram for determining arousal state.

MEASUREMENTS AND RESULTS

Strain rankings for FT% were F344 = LEW > WST during ST2 and CF. LEW and WST rats exhibited decreased rapid eye movement sleep (REM) after shock training and CF compared with baseline and control; F344 rats did not. F344 and WST rats showed increased dark-period REM after ST1, ST2, and CF compared with baseline but not with control.

CONCLUSIONS

Shock training and CF induce immediate reductions in REM in rats. However, strain differences in the amount of REM decrease did not simply relate to the strength of fear responses during shock training and CF. We speculate that reported strain differences in stress hormones, particularly prolactin, may contribute to strain differences in fear-induced alterations in REM.

Distribution of contacts from vestibulospinal axons on the dendrites of splenius motoneurons

Current descriptions of the organization of synapses on the dendritic trees of spinal motoneurons indicate that the inputs are arranged in several patterns: some are widely distributed; some are distributed to proximal dendrites; others are distributed based on the trajectory of the dendrites. However, the principles governing the organization of synapses on spinal motoneurons remain poorly defined. Our goal was to extend the descriptions of the distribution of synapses, identified by their source, on the dendritic trees of spinal motoneurons. We combined anterograde and intracellular staining techniques in cats to determine the distribution of contacts between excitatory axons from the rostral aspect of the descending vestibular nucleus and the dendrites of motoneurons supplying a dorsal neck muscle, splenius. In five of five motoneurons, the contacts were preferentially distributed on dendrites medial to the soma. This qualitative observation was confirmed by using Monte Carlo methods. The results from this analysis showed that the distribution of contacts can be explained not by the overall distribution of the dendritic membrane area but rather by a systematic innervation of the medial regions of the dendritic trees (P < 0.02). Despite this selectivity, there was no additional bias in the distribution of contacts to proximal vs. distal dendrites. By concentrating excitatory synapses in a restricted region of the dendritic tree, the actions of vestibulospinal connections on neck motoneurons may be increased as a result of a greater probability of activating persistent inward currents on the dendrites.

Cervical dystonia responsive to acoustic and galvanic vestibular stimulation

We examined the effects of acoustic and galvanic vestibular stimulation in a patient with cervical dystonia. Acoustic stimulation consisted of three conditions: "baseline" (no stimulation), "vestibular" (500 Hz bone-conducted tone bursts), and "control" (5,000 Hz tone bursts). Rectified electromyographic activity in the sternocleidomastoid was measured. Galvanic stimulation (1.5-2.5 mA current steps) was delivered to the mastoids, and head acceleration was measured. Vestibular acoustic stimulation reduced neck muscle activity between 16% and 44% (P < 0.001), and galvanic stimulation reduced head acceleration by 22.5% (P = 0.028). The patient reported subjective improvement in head control. Vestibular stimulation can reduce neck muscle activity in cervical dystonia and give symptomatic relief.

Long descending motor tract axons and their control of neck and axial muscles

It has been tacitly assumed that a long descending motor tract axon consists of a private line connecting the cell of origin to a single muscle, as a motoneuron innervates a single muscle. However, this notion of a long descending motor tract referred to as a private line is no longer tenable, since recent studies have showed that axons of all major long descending motor tracts send their axon collaterals to multiple spinal segments, suggesting that they may exert simultaneous influences on different groups of spinal interneurons and motoneurons of multiple muscles. The long descending motor systems are divided into two groups, the medial and the lateral systems including interneurons and motoneurons. In this chapter, we focus mainly on the medial system (vestibulospinal, reticulospinal and tectospinal systems) in relation to movement control of the neck, describe the intraspinal morphologies of single long descending motor tract axons that are stained with intracellular injection of horseradish peroxidase, and provide evidence that single long motor-tract neurons are implicated in the neural implementation of functional synergies for head movements.

Injury to the long thoracic nerve as a complication of neck dissection: A case report

Injury to nerves by dissection of the neck is well recognised. A case report of injury to the long thoracic nerve follows, which has not been previously described.

Temporal characteristics of neurons in the central mesencephalic reticular formation of head unrestrained monkeys

The accompanying paper demonstrated two distinct types of central mesencephalic reticular formation (cMRF) neuron that discharged before or after the gaze movement: pre-saccadic or post-saccadic. The movement fields of pre-saccadic neurons were most closely associated with gaze displacement. The movement fields of post-saccadic neurons were most closely associated with head displacement. Here we examine the relationships of the discharge patterns of these cMRF neurons with the temporal aspects of gaze or head movement. For pre-saccadic cMRF neurons with monotonically open movement fields, we demonstrate that burst duration correlated closely with gaze duration. In addition, the peak discharge of the majority of pre-saccadic neurons was closely correlated with peak gaze velocity. In contrast, discharge parameters of post-saccadic neurons were best correlated with the time of peak head velocity. However, the duration and peak discharge of post-saccadic discharge was only weakly related to the duration and peak velocity of head movement. As a result, for the majority of post-saccadic neurons the discharge waveform poorly correlated with the dynamics of head movement. We suggest that the discharge characteristics of pre-saccadic cMRF neurons with monotonically open movement fields are similar to that of direction long-lead burst neurons found previously in the paramedian portion of the pontine reticular formation (PPRF; Hepp and Henn 1983). In light of their anatomic connections with the PPRF, these pre-saccadic neurons could form a parallel pathway that participates in the transformation from the spatial coding of gaze in the superior colliculus (SC) to the temporal coding displayed by excitatory burst neurons of the PPRF. In contrast, closed and non-monotonically open movement field pre-saccadic neurons could play a critical role in feedback to the SC. The current data do not support a role for post-saccadic cMRF neurons in the direct control of head movements, but suggest that they may serve a feedback or reafference function, providing a signal of current head amplitude to upstream regions involved in head control.

Spatial characteristics of neurons in the central mesencephalic reticular formation (cMRF) of head-unrestrained monkeys

Prior studies of the central portion of the mesencephalic reticular formation (cMRF) have shown that in head-restrained monkeys, neurons discharge prior to saccades. Here, we provide a systematic analysis of the patterns of activity in cMRF neurons during head unrestrained gaze shifts. Two types of cMRF neurons were found: presaccadic neurons began to discharge before the onset of gaze movements, while postsaccadic neurons began to discharge after gaze shift onset and typically after the end of the gaze shift. Presaccadic neuronal responses were well correlated with gaze movements, while the discharge of postsaccadic neurons was more closely associated with head movements. The activity of presaccadic neurons was organized into gaze movement fields, while the activity of postsaccadic neurons was better organized into movement fields associated with head displacement. We found that cMRF neurons displayed both open and closed movement field responses. Neurons with closed movement fields discharged before a specific set of gaze (presaccadic) or head (postsaccadic) movement amplitudes and directions and had a clear distal boundary. Neurons with open movement fields discharged for gaze or head movements of a specific direction and also for movement amplitudes up to the limit of measurement (70 degrees). A subset of open movement field neurons displayed an increased discharge with increased gaze shift amplitudes, similar to pontine burst neurons, and were called monotonically increasing open movement field neurons. In contrast, neurons with non-monotonically open movement fields demonstrated activity for all gaze shift amplitudes, but their activity reached a plateau or declined gradually for gaze shifts beyond specific amplitudes. We suggest that presaccadic neurons with open movement fields participate in a descending pathway providing gaze signals to medium-lead burst neurons in the paramedian pontine reticular formation, while presaccadic closed movement field neurons may participate in feedback to the superior colliculus. The previously unrecognized group of postsaccadic cMRF neurons may provide signals of head position or velocity to the thalamus, cerebellum, or spinal cord.

Postural responses and spatial orientation to neck proprioceptive and vestibular inputs during locomotion in young and older adults

Both vestibular and neck proprioceptive inputs contribute towards maintaining a walking trajectory. We investigated how aging alters neck proprioceptive and vestibular interaction for preserving equilibrium and spatial orientation during locomotion. Young and healthy elderly were exposed to two sensory manipulations as they walked, eyes closed, to a target located straight ahead: (1) right side dorsal neck muscle vibration (Vib), and (2) Vib + transmastoidal galvanic vestibular stimulation (Vib + GVS). The maximum path deviation, average frontal centre of mass velocity and average trunk roll were evaluated. Trunk yaw rotation was computed at every metre of the path. We observed that directional responses to neck muscle stimulation were very sensitive to the reference frame generated by vestibular information. The attenuation of path deviation in older adults can be attributed to a reduced sensitivity of the neck proprioceptive system rather than the vestibular system.

Suboccipital injection with a mixture of rapid- and long-acting steroids in cluster headache: A double-blind placebo-controlled study

Oral steroids can interrupt bouts of cluster headache (CH) attacks, but recurrence is frequent and may lead to steroid-dependency. Suboccipital steroid injection may be an effective 'single shot' alternative, but no placebo-controlled trial is available. The aim of our study was to assess in a double-blind placebo-controlled trial the preventative effect on CH attacks of an ipsilateral steroid injection in the region of the greater occipital nerve. Sixteen episodic (ECH) and seven chronic (CCH) CH outpatients were included. ECH patients were in a new bout since no more than 1 week. After a one-week run-in period, patients were allocated by randomization to the placebo or verum arms and received on the side of attacks a suboccipital injection of a mixture of long- and rapid-acting betamethasone (n=13; Verum-group) or physiological saline (n=10; Plac-group). Acute treatment was allowed at any time, additional preventative therapy if attacks persisted after 1 week. Three investigators performed the injections, while four others, blinded to group allocation, followed the patients. Follow-up visits were after 1 and 4 weeks, whereafter patients were followed routinely. Eleven Verum-group patients (3 CCH) (85%) became attack-free in the first week after the injection compared to none in the Plac-group (P=0.0001). Among them eight remained attack-free for 4 weeks (P=0.0026). Remission lasted between 4 and 26 months in five patients. A single suboccipital steroid injection completely suppresses attacks in more than 80% of CH patients. This effect is maintained for at least 4 weeks in the majority of them.

High division of the accessory nerve: a rare anatomical variation as a possible pitfall during neck dissection surgery

A rare clinical variant found during neck dissection surgery is reported in which the spinal accessory nerve divided at a high level in the neck, before entering the sternocleidomastoid muscle. This case documents the need for meticulous technique in identification and dissection of the spinal accessory nerve in order to reduce the risk of postoperative morbidity.

Electrophysiologic identification and evaluation of stylohyoid and posterior digastricus muscle complex

PURPOSE

To identify the function of stylohyoid and posterior digastricus (STH-PD) muscle complex by the EMG techniques.

METHODS

Unaffected sides of the faces of 30 patients with facial paralysis or hemifacial spasm were investigated. A concentric needle electrode was inserted to the STH-PD muscle complex and another concentric needle electrode was inserted to the orbicularis oris (OO) muscle. Simultaneous recording were obtained from two muscles using electrical stimulation (ES) (in 25 cases) and magnetic coil stimulation (MS) (in 15 cases); and both in 10 cases. Afterwards, the function of STH-PD was studied such as whistling, lip pursing, swallowing, jaw opening and closing.

RESULTS

(1) The motor latency of compound muscle action potential (CMAP) of the STH-PD muscle was shorter than that of OO. (2) When the facial nerve was stimulated more distally than the stylomastoid foramen, the CMAP elicited from the STH-PD muscle complex immediately disappeared. (3) Ipsilateral MS was able to elicit the motor evoked potential (MEP) from STH-PD either at intracranially (half of cases) or at the extracranially. While OO muscle was always stimulated intracranially by MS. (4) The STH-PD muscle complex could not be basically recruited by the mimicry except lip pursing. The main recruitment were provided by swallowing and jaw opening. Cortical MS were facilitated during swallowing (5) Late reflex responses appeared in the STH-PD muscle complex during infraorbital-trigeminal and facial nerve ES.

CONCLUSION

The STH-PD muscle complex is identified electrophysiologically. Although it is innervated by the facial nerve, its functions are mainly related with jaw opening and oropharyngeal swallowing. However, it is activated by the lip pursing.

Effect of gaze direction on neck muscle activity during cervical rotation

Control of the neck muscles is coordinated with the sensory organs of vision, hearing and balance. For instance, activity of splenius capitis (SC) is modified with gaze shift. This interaction between eye movement and neck muscle activity is likely to influence the control of neck movement. The aim of this study was to investigate the effect of eye position on neck muscle activity during cervical rotation. In eleven subjects we recorded electromyographic activity (EMG) of muscles that rotate the neck to the right [right obliquus capitis inferior (OI), multifides (MF), and SC, and left sternocleidomastoid (SCM)] with intramuscular or surface electrodes. In sitting, subjects rotated the neck in each direction to specific points in range that were held statically with gaze either fixed to a guide (at three different positions) that moved with the head to maintain a constant intra-orbit eye position or to a panel in front of the subject. Although right SC and left SCM EMG increased with rotation to the right, contrary to anatomical texts, OI EMG increased with both directions and MF EMG did not change from the activity recorded at rest. During neck rotation SCM and MF EMG was less when the eyes were maintained with a constant intra-orbit position that was opposite to the direction of rotation compared to trials in which the eyes were maintained in the same direction as the head movement. The inter-relationship between eye position and neck muscle activity may affect the control of neck posture and movement.

Cutaneous sensory branch of the mylohyoid nerve

The study is aimed at the anatomical detail of the cutaneous sensory branch of the mylohyoid nerve (MHN), which is distributed to the chin, as it relates to submental surgery. Dissection was done on the both sides (16) of eight cadavers fixed in formaldehyde solution. A distance from gonion of the branch innervating the anterior digastric and mylohyoid muscle and the cutaneous sensory branch was measured. The cutaneous sensory nerve was 27.0+/-8.6 mm long and numbered 2.3 (14.4%) of 16 specimens. The area distributed by most branches (78%) was a rhombus, having all four sides equal (15 mm), extending to the mental prominence and submentum. The divergent angle of the two facing sides of the bilateral rhombi was 60 degrees. Informed surgical manipulation of the mental area may avoid unnecessary damage to the sensory nerve.

Are tender points associated with cervical radiculopathy?

OBJECTIVE

To determine if there is an association between cervical radiculopathy and tender spots in the neck and upper extremity on the side of radiculopathy.

DESIGN

Prospective cross-sectional study.

SETTING

Outpatient spine clinic within an academic institution.

PARTICIPANTS

Convenience sample of 16 subjects with unilateral cervical radiculopathy. Twelve subjects had C7 radiculopathy and 4 had C6 or C8 radiculopathy.

INTERVENTION

Bilateral pain-pressure threshold measurement (14 muscles) of the neck and upper extremity.

MAIN OUTCOME MEASURE

Side-to-side difference in pain-pressure threshold.

RESULTS

Differences in frequency of tender spots were found only in the deltoid and flexor carpi radialis. Overall, more tender spots were found on the side of radiculopathy (75 vs 34, P < .01). Among subjects with C7 radiculopathy, the number of tender spots in C7 innervated muscles was greater on the side of radiculopathy (23 vs 7, P < .02). In contrast, no significant difference in the number of tender spots between sides was found when only non-C7 innervated muscles (P > 0.1) were considered.

CONCLUSIONS

Cervical radiculopathy was associated with increased tender spots on the side of radiculopathy, with predilection toward muscles innervated by the involved nerve root.

Donor, recipient and nerve grafts in brachial plexus reconstruction: anatomical and technical features for facilitating the exposure

Forty three cadavers of adult and five patients were included in our study. Accessory, suprascapular, musculocutaneous and sural nerves were dissected. These widely used nerves in brachial plexus reconstruction have varying anatomy and still have no standard approach for surgery. Dissection of the accessory nerve in the upper part of the posterior neck triangle was quite complicated took a relatively long time and the nerve could easily be injured. It was found that these shortcomings could be diminished starting dissection of this nerve in the lower part of the posterior neck triangle near the anterior border of trapezius muscle 2 cm (0-3.5) above the clavicle. Accessory nerve entered inner surface of this muscle 3 cm (1-4) from this edge. The proximal portion of the suprascapular nerve was not difficult to identify if post-traumatic scarring is absent. Alternative approach was starting dissection from the junction of C5 and C6 into superior trunk. The suprascapular nerve diverged distally from this junction at 2 cm (0-2.5). The proximal portion of the musculocutaneous nerve was identified by cutting clavicle or tendon of major pectoral muscle. Quicker and less traumatic exposure of this nerve was starting dissection in the bed between biceps and coracobrachialis muscles. The first branches of the musculocutaneous nerve to the biceps brachii muscle took onset 4 cm (3.5-6) distally from the lower margin of the tendon of major pectoral muscle. First branch to the brachial muscle originated from the musculocutaneous nerve distally from the same tendon at 9.4 cm (6.1-10.5). Two main but controversial principles exist in sural nerve graft dissection: time saving and less traumatic approach. Long nerve graft is necessary during brachial plexus reconstruction when many interposition grafts are needed. Technique of multiple (4-7) transverse skin incisions let us to get sural nerve with both branches as long as 66 cm (average 47 cm). Total length of this nerve mainly depended on branching level, which was found to be 27.5 cm (9-35) measuring proximally from the lateral ankle.

Variations in the surface anatomy of the spinal accessory nerve in the posterior triangle

Iatrogenic injury to the spinal accessory nerve has been widely documented and can have medico-legal implications. The resulting syndrome of pain, paralysis and winging of the scapula are often the source of considerable morbidity. This paper researches the degree of accuracy achievable in mapping the surface anatomy of the spinal accessory nerve in the region of the posterior triangle with a view to creating a cartographical aid to surgical procedures. The necks of 25 adult cadavers were dissected bilaterally to expose the spinal accessory nerve. Variations in the course and distribution of the spinal accessory nerve in the posterior triangle were recorded along with its relationship to the borders of sternocleidomastoid and trapezius. Considerable variation was seen in the surface and regional anatomy of the nerve and in the contribution of the cervical plexus to the spinal accessory nerve in the posterior triangle. Measurements of the running course and exit point of the nerve into and from the posterior triangle differed significantly from those previously recorded. Delineation of an accurate surface anatomy was not possible. Creating a map to define the surface anatomy of the spinal accessory nerve in the posterior triangle is an unrealistic goal given its wide variations in man. Avoidance of damage to the spinal accessory nerve cannot be achieved by slavishly adhering to surface markings given in textbooks, but only by cautious dissection during operations on the posterior triangle.