Brachial Plexus Traction Injury: Quantification of Sensory Abnormalities

Micropatterned Poly(D,L-Lactide-Co-Caprolactone) Conduits With KHI-Peptide and NGF Promote Peripheral Nerve Repair After Severe Traction Injury

Severe traction injuries after stretch to peripheral nerves are common and challenging to repair. The nerve guidance conduits (NGCs) are promising in the regeneration and functional recovery after nerve injuries. To enhance the repair of severe nerve traction injuries, in this study KHIFSDDSSE (KHI) peptides were grafted on a porous and micropatterned poly(D,L-lactide-co-caprolactone) (PLCL) film (MPLCL), which was further loaded with a nerve growth factor (NGF). The adhesion number of Schwann cells (SCs), ratio of length/width (L/W), and percentage of elongated SCs were significantly higher in the MPLCL-peptide group and MPLCL-peptide-NGF group compared with those in the PLCL group in vitro. The electromyography (EMG) and morphological changes of the nerve after severe traction injury were improved significantly in the MPLCL-peptide group and MPLCL-peptide-NGF group compared with those in the PLCL group in vivo. Hence, the NGCs featured with both bioactive factors (KHI peptides and NGF) and physical topography (parallelly linear micropatterns) have synergistic effect on nerve reinnervation after severe traction injuries.

Neck-specific exercise for radiating pain and neurological deficits in chronic whiplash, a 1-year follow-up of a randomised clinical trial

Up to 90% of people with neurological deficits following whiplash injury report chronic symptoms. A recent unique study of neck-specific exercise showed positive results (post-intervention at 12 weeks), regarding arm pain and neurological deficits in people with chronic whiplash associated disorders (WAD). This 1-year follow-up of that randomised controlled study with assessor blinding aimed to examine whether neck-specific exercise with (NSEB) or without (NSE) a behavioural approach has long-term benefits over physical activity prescription (PPA) regarding arm pain and neurological deficits (n = 171). Interventions were: NSE, NSEB, or PPA. Follow-up of arm pain, paraesthesia bothersomeness (questionnaires) and clinical neurological tests were performed after 3, 6 and 12 months and analysed with Linear Mixed Models and General Estimating Equations. The NSE and/or NSEB groups reported significantly less pain and paraesthesia bothersomeness as well as higher odds of normal key muscle arm strength and of normal upper limb neural tension over the year (all p < 0.03), compared with PPA. In conclusion, results suggest that neck-specific exercise with or without a behavioural approach may have persisting long term benefits over PPA regarding arm pain and clinical signs associated with neurological deficits in chronic WAD.

Neck-specific exercise may reduce radiating pain and signs of neurological deficits in chronic whiplash - Analyses of a randomized clinical trial

Up to 90% of people with neurological deficits following a whiplash injury do not recover and cervical muscle dysfunction is common. The aim of this multicentre, randomized controlled trial was to examine whether two versions of neck-specific exercise or prescription of physical activity (PPA) can improve radiating arm pain and clinical signs that can be associated with neurological deficits in people with chronic whiplash associated disorders (WAD). Participants with chronic WAD, arm symptoms and signs associated with neurological deficits (n = 171) were randomized to: 12 weeks of neck-specific exercise without (NSE) or with a behavioural approach (NSEB), or PPA. Pain/bothersomeness frequency, six measures of arm pain/paraesthesia (VAS scales), and four clinical neurological tests were evaluated after 3 months. The NSE group reported the lowest frequency and lowest levels of arm pain, the highest proportion of participants with at least 50% pain reduction and the highest proportion of normal arm muscle force. The NSEB group reported increased normal tendon reflexes. No improvements were recorded for the PPA group. Neck-specific exercise may improve arm pain and decrease signs of neurological deficits, but the addition of a behavioural approach does not seem to be of additional benefit.

Protective Effect of Moderate Exogenous Electric Field Stimulation on Activating Netrin-1/DCC Expression Against Mechanical Stretch-Induced Injury in Spinal Cord Neurons

Nerve cells detect and respond to electric field stimulation and extrinsic chemical guidance cues during development and regeneration; therefore, the development and optimization of an approach for functional neuronal regeneration are necessary for a nerve injury. In this study, we proposed using electric field stimulation to repair a nerve injury triggered by serious mechanical stretch loading. A device that provides continuous mechanical stretch and constant electric field stimulation was designed. Primary dissociated spinal cord neurons were stimulated by mechanical stretch (tensile strain 2.5-10%) at different times (1, 4, 8, and 12 h) to set up a moderate nerve injury model. Stimulated samples were evaluated with respect to cell viability, density, and axonal elongation by the MTT and immunofluorescence assays. The results indicated that mechanical stretch (S, 5% tensile strain, 4 h) caused moderate axonal injury, resulting in significant loss of cell viability and a decrease in cell density. However, injured spinal cord neurons became viable after electric field stimulation (E, 33 mA/m², 4 h) in the fluorescein diacetate assay. In addition, neuronal viability, density, and elongation increased significantly after electric field stimulation compared with those of stretch-injured neurons. Moreover, electric field stimulation significantly activated the axonal guidance cues Netrin-1 and deleted in colorectal cancer (DCC) receptor expression compared with the stretch-injury group. These results indicate that electric stimulation activates synergistic guidance cues of expression to improve axonal growth relevant to nerve injuries. Our study provides new insight into neuronal regeneration.

The clinical characteristics of neuropathic pain in patients with total brachial plexus avulsion: A 30-case study

Neuropathic pain in patients with total brachial plexus avulsion has always been a sophisticated problem in clinical practice.

OBJECTIVES

For further researches on objective diagnosis, alleviation or even cure of neuropathic pain, we need to conclude the basic clinical features including pain intensity, distribution, type and possible risk factors.

METHODS

Thirty cases of patients with total brachial plexus avulsion were included and their baseline information was collected. Pain was evaluated by Present Pain Index using a visual analog scale; Douleur Neuropathique 4 was used for screening neuropathic pain. For more detailed pain description, the Neuropathic Pain Symptoms Inventory questionnaire and a picture showing the exact pain district were both fulfilled by all the eligible participants. The relationship between neuropathic pain and basic information, injury conditions, accompanied conditions and quality of life was tested.

RESULTS

All the participants were male in both groups. The neuropathic pain group contained 22 patients (73.33%) with the mean age of 30.18±9.47; while 29.00±7.95 in the other group. Patients with neuropathic pain presented variously in pain degree, location, type and time phase, according to the results of the Neuropathic Pain Symptoms Inventory questionnaire. Nevertheless, most pain distributed on the region of hand. Among several related factors, alcohol abuse may be possible risk factors of neuropathic pain (p=0.03). Quality of life was significantly affected by pain (p<0.01).

CONCLUSION

Neuropathic pain in patients with total brachial avulsion was characterized with heterogeneity in pain distribution, intensity, type and also time phase. Bad life habits might be risk factors associated with neuropathic pain. Neuropathic pain might affect quality of life of the patients with total brachial plexus avulsion remarkably.

Chronic post-traumatic neuropathic pain of brachial plexus and upper limb: a new technique of peripheral nerve stimulation

The aim of the study was to evaluate the effect on pain relief in patients with peripheral neuropathic pain after brachial plexus injuries using an implanted peripheral nerve stimulator applied directly to the nerve branch involved into the axillary cavity. Seven patients with post-traumatic brachial plexus lesions or distal peripheral nerve complaining of severe intractable chronic pain were enrolled in a single-centre, open-label trial. Conventional drugs and traditional surgical treatment were not effective. Patients underwent careful neurological evaluation, pain questionnaires and quantitative sensory testing (QST). Surgical treatment consists of a new surgical technique: a quadripolar electrode lead was placed directly on the sensory peripheral branch of the main nerve involved, proximally to the site of lesion, into the axillary cavity. To assess the effect, we performed a complete neuroalgological evaluation and QST battery after 1 week and again after 1, 6 and 12 weeks. All patients at baseline experienced severe pain with severe positive phenomena in the median (5) and/or radial (2) territory. After turning on the neuro-stimulator system, all patients experienced pain relief within a few minutes (>75 % and >95 % in most), with long-lasting pain relief with a reduction in mean Numerical Rating Scale (NRS) of 76.2 % after 6 months and of 71.5 % after 12 months. No significant adverse events occurred. We recommend and encourage this surgical technique for safety reasons; complications such as dislocation of electrocatheters are avoided. The peripheral nerve stimulation is effective and in severe neuropathic pain after post-traumatic nerve injuries of the upper limbs.

Elevated blood levels of inflammatory monocytes (CD14+ CD16+ ) in patients with complex regional pain syndrome

Complex regional pain syndrome (CRPS) is a chronic pain disorder. Although its pathophysiology is not completely understood, neurogenic inflammation is thought to play a significant role. Microglia and astrocytes are activated following tissue injury or inflammation and have been reported to be both necessary and sufficient for enhanced nociception. Blood-borne monocytes/macrophages can infiltrate the central nervous system (CNS) and differentiate into microglia resulting in hypersensitivity and chronic pain. The primary aim of this study was to evaluate the proportion of the proinflammatory CD14(+) CD16(+) monocytes as well as plasma cytokine levels in blood from CRPS patients compared to age- and gender-matched healthy control individuals. Forty-six subjects (25 CRPS, 21 controls) were recruited for this study. The percentage of monocytes, T, B or natural killer (NK) cells did not differ between CRPS and controls. However, the percentage of the CD14(+) CD16(+) monocyte/macrophage subgroup was elevated significantly (P<0·01) in CRPS compared to controls. Individuals with high percentage of CD14(+) CD16(+) demonstrated significantly lower (P<0·05) plasma levels on the anti-inflammatory cytokine interleukin (IL)-10. Our data cannot determine whether CD14(+) CD16(+) monocytes became elevated prior to or after developing CRPS. In either case, the elevation of blood proinflammatoty monocytes prior to the initiating event may predispose individuals for developing the syndrome whereas the elevation of blood proinflammatory monocytes following the development of CRPS may be relevant for its maintenance. Further evaluation of the role the immune system plays in the pathogenesis of CRPS may aid in elucidating disease mechanisms as well as the development of novel therapies for its treatment.

The effect of mechanical strain or hypoxia on cell death in subpopulations of rat dorsal root ganglion neurons in vitro

Spinal nerves and their associated dorsal root ganglion (DRG) cells can be subject to mechanical deformation and hypoxia associated with pathology such as disc herniation, spinal stenosis and spine trauma. There is very limited information on the response of adult DRG neurons to such stressors. In this study we used an in vitro approach to examine the response of adult DRG cells to (a) mechanical, hypoxic, and combined injuries; and (b) to compare the effects on injury on nociceptive and non-nociceptive neurons, as well as on non-neuronal cells. Mechanical injury (20% tensile strain) led to significant neuronal cell death (assessed by ethidium homodimer-1 labelling), which was proportional to strain duration (5 min, 1 h, 6 h or 18 h). Hypoxia (2% O(2) for 24 h) also promoted death of DRG neurons, and was further enhanced when mechanical strain and hypoxia were combined. Both mechanical strain and hypoxia significantly decreased the maximum neurite length. Conversely, death of non-neuronal cells was only increased by hypoxia and not by mechanical strain. Total cell death in response to mechanical injury or hypoxia was similar in both non-nociceptive (neurofilament, NF-200 immunoreactive) and nociceptive (calcitonin gene-related peptide, CGRP immunoreactive) neurons, but apoptosis (assessed by activated caspase-3 immunostaining) was significantly higher in CGRP than NF-200 neurons. Surprisingly, cell death of non-peptidergic nociceptors (identified by Griffonia simplicifolia IB4 lectin binding) was already high in control cultures, and was not increased further by either mechanical stretch or hypoxia. These results provide detailed information on the response of adult DRG subpopulations to hypoxia and mechanical strain, and describe in vitro models that could be useful for screening potential neuroprotective agents.

Outpatient intravenous ketamine for the treatment of complex regional pain syndrome: a double-blind placebo controlled study

Complex regional pain syndrome (CRPS) is a severe chronic pain condition that most often develops following trauma. The pathophysiology of CRPS is not known but both clinical and experimental evidence demonstrate the important of the NMDA receptor and glial activation in its induction and maintenance. Ketamine is the most potent clinically available safe NMDA antagonist that has a well established role in the treatment of acute and chronic pain. This randomized double-blind placebo controlled trial was designed to evaluate the effectiveness of intravenous ketamine in the treatment of CRPS. Before treatment, after informed consent was obtained, each subject was randomized into a ketamine or a placebo infusion group. Study subjects were evaluated for at least 2 weeks prior to treatment and for 3 months following treatment. All subjects were infused intravenously with normal saline with or without ketamine for 4h (25ml/h) daily for 10 days. The maximum ketamine infusion rate was 0.35mg/kg/h, not to exceed 25mg/h over a 4h period. Subjects in both the ketamine and placebo groups were administered clonidine and versed. This study showed that intravenous ketamine administered in an outpatient setting resulted in statistically significant (p<0.05) reductions in many pain parameters. It also showed that subjects in our placebo group demonstrated no treatment effect in any parameter. The results of this study warrant a larger randomized placebo controlled trial using higher doses of ketamine and a longer follow-up period.