Does the addition of a nerve wrap to a motor nerve repair affect motor outcomes?

The purpose of this study was to evaluate the effect of wrapping bioabsorbable nerve conduit around primary suture repair on motor nerve regeneration in a rat model. Forty rats were randomly divided into two experimental groups according to the type of repair of the rat sciatic nerve: group I had primary suture repair; group II had primary suture repair and bioabsorbable collagen nerve conduit (NeuraGen® 1.5 mm, Integra LifeSciences Corp., Plainsboro, NJ) wrapped around the repair. At 12 weeks, no significant differences in the percentage of recovery between the two groups were observed with respect to compound muscle action potentials, isometric muscle force, and muscle weight (P = 0.816, P = 0.698, P = 0.861, respectively). Histomorphometric analysis as compared to the non‐operative sites was also not significantly different between the two groups in terms of number of myelinated axons, myelinated fiber area, and nerve fiber density (P = 0.368, P = 0.968, P = 0.071, respectively). Perineural scar tissue formation was greater in primary suture repair group (0.36 ± 0.15) than in primary repair plus conduit wrapping group (0.17 ± 0.08). This difference was statistically significant (P < 0.001). Wrapping bioabsorbable nerve conduit around primary nerve repair can decrease perineural scar tissue formation. Although the scar‐decreasing effect of bioabsorbable nerve wrap does not translate into better motor nerve recovery in this study, it might have an effect on the functional outcome in humans where scar formation is much more evident than in rats. © 2014 Wiley Periodicals, Inc. Microsurgery 34:562–567, 2014.     

What mechanism justifies abdominal evaluation in motor vehicle crashes?

BACKGROUND: Significant resources are spent on assessment of the abdomen in motor vehicle crash (MVC) occupants based solely upon crash mechanism. Most have no clinically significant injuries. We sought to define crash and occupant characteristics that would be associated with a low probability of clinically significant abdominal injury. METHODS: Drivers in MVCs were analyzed from the National Automotive Sampling System from 1993 to 2001. The probability of abdominal injury with an Abbreviated Injury Score > 1 was measured over a range of crash velocities controlling for other covariates using multivariate logistic regression. A receiver operating curve was used to assess the model. RESULTS: Age, restraint use, net change in velocity, ejection, rollover, vehicle type, other passenger mortality, and other injuries were included in the model yielding an area under the receiver operating curve of 0.948. The probability of abdominal injury increased significantly at velocities >20 km/h and reached 5.0% at approximately 30 km/h. Age >75 years old or the presence of head, leg, or chest injuries significantly increased the risk of abdominal injury, even at low velocities. Absence of injury to the head, spine, legs, or chest indicated that the abdomen was unlikely to be injured regardless of crash velocity. CONCLUSION: Absence of injury to the head, chest, spine, and legs indicates an extremely low probability of abdominal injury, even at high velocities. Abdominal evaluation in this group of patients for reason of mechanism alone is therefore unnecessary.     

Placebo--the drug of choice in female motor urge incontinence?

In a randomised double-blind cross-over trial of 19 females with motor urge incontinence but without bladder suspension defect, the effects of 14 days' treatment with emepronium bromide 200 mg qid, flavoxate chloride 200 mg qid or placebo qid were compared by means of micturition charts, the patients' drug preferences and evaluation of side effects. Placebo was the only drug giving rise to a statistically significant decrease in the frequency of voidings, incontinence and nocturia. Forty-seven per cent of the patients preferred placebo and side effects were less frequent during treatment with this medication. No differences could be demonstrated between the effects of emepronium bromide and flavoxate chloride. Perhaps detrusor instability is not always the main reason for the voiding dysfunction in these patients, in whom the effect of placebo was equal or superior to the effect of "active drugs" and superior to no treatment at all.     

Human θ burst stimulation enhances subsequent motor learning and increases performance variability

Intermittent theta burst stimulation (iTBS) transiently increases motor cortex excitability in healthy humans by a process thought to involve synaptic long-term potentiation (LTP), and this is enhanced by nicotine. Acquisition of a ballistic motor task is likewise accompanied by increased excitability and presumed intracortical LTP. Here, we test how iTBS and nicotine influences subsequent motor learning. Ten healthy subjects participated in a double-blinded placebo-controlled trial testing the effects of iTBS and nicotine. iTBS alone increased the rate of learning but this increase was blocked by nicotine. We then investigated factors other than synaptic strengthening that may play a role. Behavioral analysis and modeling suggested that iTBS increased performance variability, which correlated with learning outcome. A control experiment confirmed the increase in motor output variability by showing that iTBS increased the dispersion of involuntary transcranial magnetic stimulation-evoked thumb movements. We suggest that in addition to the effect on synaptic plasticity, iTBS may have facilitated performance by increasing motor output variability; nicotine negated this effect on variability perhaps via increasing the signal-to-noise ratio in cerebral cortex.     

Evaluating the “cushion effect” among children in frontal motor vehicle crashes

Background

The “Cushion Effect,” the phenomenon in which obesity protects against abdominal injury in adults in motor vehicle accidents, has not been evaluated among pediatric patients. This work evaluates the association between subcutaneous fat cross-sectional area, quantified using analytic morphomic techniques and abdominal injury.

The thenar motor branch during carpal tunnel decompression: “the expert opinion”

Introduction Iatrogenic injury to the thenar motor branch (TMB) of the median nerve is a rare but serious complication of carpal tunnel decompression (CTD). Variability in the anatomical course of the branch is well documented in the literature. We aimed to explore and document “expert experience and attitude” to the TMB during CTD. Materials and methods All members of the British Society for Surgery of the Hand (220) were sent a short postal questionnaire, in which 153 questionnaires (70%) were returned. Results The open technique was routinely used by 97% of the surgeons, 70% replied that either very rarely or never formally explored the TMB during CTD and 71% of surgeons saw the TMB lying superficially in less than 5% of cases. Among surgeons, 49 had never encountered an iatrogenic injury while only 14 had seen more than 5 cases in their careers. Finally, 71% of surgeons agreed that formal exploration of the nerve is not necessary during uncomplicated cases. Discussion The “consensus” view suggests that formal demonstration of the thenar branch of the median nerve during CTD is unnecessary. The incidence of iatrogenic injuries seen was low. A number of useful strategies to avoid iatrogenic injuries are suggested.     

The hazards of off-road motor sports: Are four wheels better than two?

BackgroundOff-road motorsports are an increasing popular activity, yet the relative safety profile of all-terrain vehicles (ATV) to off-road motorcycles (ORMC) has not been compared.Study designA retrospective review of the 2002–2006 US National Trauma Data Bank of ATV and ORMC crash victims. Patients were described according to demographic (age, sex, race and ethnicity, insurance status) and injury characteristics (Injury Severity Score, hypotension, motor component of the Glasgow Coma Score, presence of a severe head or extremity injury) known to affect trauma outcomes. Logistic regression evaluated the independent effect of an ATV vehicle on mortality, intensive care unit (ICU) admission, and placement on a ventilator relative to ORMC. The anatomic distribution of severe injuries was compared between survivors and decedents within each vehicle type.ResultsA total of 34,457 patients met inclusion criteria, of whom, 24,582 were ATV patients and 9875 were ORMC patients. ATV patients had 51% higher risk-adjusted odds of death (OR 1.51; 95% CI 1.03–2.20), 55% higher risk-adjusted odds of being admitted to an ICU (OR 1.55; 95% CI 1.42–1.70), and 42% higher risk-adjusted odds of being placed on a ventilator (OR 1.42, 95% CI 1.17–1.72) compared to ORMC crash victims. Decedents in both vehicle types were more likely to suffer severe head, thoracic, and abdominal injuries relative to their surviving counterparts.ConclusionFor injured riders, ATVs are associated with increased mortality and higher resource utilisation compared to ORMCs. Both groups suffer distinct anatomic injuries, suggesting the need for focused areas of injury prevention planning and research.     

Are there excitability changes in the hand motor cortex during speech in left-handed subjects?

Hemispheric dominance was investigated in left-handed subjects using single transcranial magnetic stimulation to assess the possible effect of forced change in the dominant hand. Single transcranial magnetic stimuli were delivered randomly over the hand area of the left or right motor cortex of 8 Japanese self-declared left-handed adult volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects read aloud. Laterality quotient calculated by the Edinburgh Inventory ranged from -100 to -5.26 and laterality index calculated from motor evoked potentials ranged from -86.2 to 38.8. There was no significant correlation between laterality quotient and laterality index. Mean data values across all 8 subjects indicated significant increases only in the left hand. Our ratio analysis of facilitation of the hand motor potentials showed that 2 each of the 8 self-declared left-handers were right- and left-hand dominant and the other 4 were bilateral-hand dominant. Speech dominancy was localized primarily in the right cerebral hemisphere in left-handed subjects, but some individuals exhibited bilateral or left dominance, possibly attributable to the forced change of hand preference for writing in childhood. Our findings suggest changes in the connections between the speech and hand motor areas.     

End-to-side neurorrhaphy of motor nerves: reinnervation of free muscle transplants—first clinical application

End-to-side neurorrhaphy may offer a practical solution in limited cases of nerve reconstruction when no donor nerve or nerve transfer is available for direct end-to-end nerve suture, or when extremely long distances for nerve regeneration cause irreversible atrophy of the targets. We report our experience with the successful clinical use of a completely new technique of end-to-side neurorrhaphy for motor reinnervation of free functional muscle transplants. Since 1995 we have used end-to-side nerve repair for motor or sensory reinnervation in 13 cases. A free functional muscle graft was reinnervated by an end-to-side neurorrhaphy in four patients after tumor resection (two myocutaneous latissimus dorsi flaps), Volkmann's contracture (one myocutaneous latissimus dorsi flap), and in a long-standing brachial plexus lesion (one gracilis muscle flap). All four patients showed reinnervation of their muscle graft through the end-to-side nerve suture site. Two functional muscle grafts to the upper extremity had positive outcome of M3-M4 for elbow and finger extension in one case, and M4 for finger flexion in one case more than 2 years after transplantation. The transplant in the brachial plexus lesion is too early for a final functional result. One patient had a M3 for knee extension 8 months postoperatively. In the clinical cases there was no downgrading of the muscle functions supplied by the "donor" nerve. Good and clinically relevant reinnervation of a functional muscle graft is possible through an end-to-side nerve suture. Proximal avulsion, missing proximal nerve stumps, partial recovery, shortening of long distances for nerve regeneration, and prevention of long nerve grafts in proximal lesions are good indications for reinnervation of a functional muscle transplant by end-to-side neurorrhaphy without harm to the donor nerve. Donor nerves supplying synergists should be preferred.