Defining neuropathic pain

Clinical research and practice have suffered because of lack of specificity when clinical diagnoses of pain are made. Distinction between neuropathic and inflammatory pain mechanisms is suggested, as well as the distinction between neuropathic pain from hypersensitivity pain disorders, previously termed neuropathic pain due to neurological dysfunction. Neuropathic pain is in this case defined as pain occurring in the ara of body affected by neurological disease or injury. This type of pain manifests not only with positive sensory phenomena such as pain, dysesthesia, and different types of hyperalgesia, but also with negative sensory phenomena and negative and positive motor and autonomic symptoms and signs.     

Age-dependent development of chronic neuropathic pain, allodynia and sensory recovery after upper limb nerve injury in children

Forty-nine children with distal upper limb nerve injury were studied at a mean follow-up of 2 years 3 months. Patients who were aged 5 years or younger at the time of nerve injury (15/49) had no chronic neuropathic pain symptoms or allodynia. Patients with allodynia on quantitative sensory testing but no spontaneous pain (8/49) were all older than 5 years and those reporting spontaneous chronic neuropathic pain (5/49) were all older than 12 years at the time of injury. Previous studies of adults with similar nerve injuries report chronic hyperaesthesia in up to 40% of cases. Semmes-Weinstein monofilament testing showed a positive correlation between age at injury and abnormal sensory threshold (r = 0.60, P<0.0001). These findings indicate that young children show better sensory recovery and are less likely to develop long-term chronic neuropathic pain syndromes than adults following nerve injury.     

Neurological complication after the "tailor posture" during labour with epidural analgesia

Obstetrical positioning is used more and more often because of the supposed or proven benefits although side effects are not well known. We therefore report the case of a patient who presented with a postpartum neurological deficit after a seven hour hip-flexed posture during labour under epidural analgesia. The parturient did not complain of pain or discomfort during labour. The neurological injury was suspected because of delayed recovery of epidural analgesia-induced motor block. Neurological examination disclosed sensory and motor abnormalities in the left femoral and sciatic nerve distribution areas. The early performed lumbar CT-scan did not show any complication and electromyographic evaluation performed on the ninth postpartum day was normal. Three months after delivery, some degree of neuropathic pain in the sciatic nerve distribution remained. The risk of neurological injury directly related to obstetrical positioning is discussed. Prolonged positioning using a posture which can induce nerve stretching should be avoided. This is especially true when the patient is receiving epidural analgesia which can mask pain or discomfort.     

Different symptoms of neuropathic pain can be induced by different degrees of compressive force on the C7 dorsal root of rats

Background contextNeuropathic pain after nerve injuries is characterized by positive and negative sensory symptoms and signs. The extent of sensory fiber loss after nerve injuries has been demonstrated to correlate with symptoms of neuropathic pain by quantitative sensory testing and confirmed by biopsies of small nerve fibers. However, the relationship between the pathologic changes of large nerves on injuries and resulting pain symptoms remains unclear.PurposeTo investigate the relationship between the extent of dorsal root injury and resulting symptoms of neuropathic pain.Study designNerve injury and assessment of the following pain-related behaviors and neuropathologic changes.MethodsA total of 24 adult male Sprague-Dawley rats weighing 250 to 300 g were randomly divided into three groups (n=8 each): sham group operated on but without nerve compression, 70 gf group, and 180 gf group; a compression force of 70 or 180 g was applied to the right C7 dorsal root, separately. Threshold thermal and mechanical pains were measured before surgery (baseline) and on the first, third, fifth, and seventh day after surgery. On the seventh day after surgery, all rats were killed, and the structural alterations of nerve fibers within the compressed areas were examined.ResultsA compression force of 70 g resulted in hyperalgesia, whereas a compression force of 180 g induced hypoalgesia in the ipsilateral forepaw in response to both mechanical and thermal stimulations within 7 days after injury. Light microscopy and electron microscopy revealed a mild to moderate sensory fiber loss after 70-gf compression and a more severe sensory fiber loss after 180-gf compression.ConclusionsTransient injuries on sensory fibers can produce either positive or negative symptoms of neuropathic pain, and the different extent of sensory fiber loss after different degrees of injuries might account for the varied resulting symptoms of neuropathic pain.     

The role of sacroiliac joint dysfunction in the genesis of low back pain: the obvious is not always right

Background context It is a common practice to the link low back pain with protruding disc even when neurological signs are absent. Because pain caused by sacroiliac joint dysfunction can mimic discogenic or radicular low back pain, we assumed that the diagnosis of sacroiliac joint dysfunction is frequently overlooked. Purpose To assess the incidence of sacroiliac joint dysfunction in patients with low back pain and positive disc findings on CT scan or MRI, but without claudication or objective neurological deficits. Methods Fifty patients with low back pain and disc herniation, without claudication or neurological abnormalities such as decreased motor strength, sensory alterations or sphincter incontinence and with positive pain provocation tests for sacroiliac joint dysfunction were submitted to fluoroscopic diagnostic sacroiliac joint infiltration. Results The mean baseline VAS pain score was 7.8 ± 1.77 (range 5–10). Thirty minutes after infiltration, the mean VAS score was 1.3 ± 1.76 (median 0.000E+00 with an average deviation from median = 1.30) (P = 0.0002). Forty-six patients had a VAS score ranging from 0 to 3, 8 weeks after the fluoroscopic guided infiltration. There were no serious complications after treatment. An unanticipated motor block that required hospitalization was seen in four patients, lasting from 12 to 36 h. Conclusions Sacroiliac joint dysfunction should be considered strongly in the differential diagnosis of low back pain in this group of patients.     

Hydrosyringomyelia associated with a Chiari I malformation in children and adolescents

The clinical presentation, radiological features, and results of surgical treatment were analyzed in 17 cases of hydrosyringomyelia associated with a Chiari malformation, in children and adolescents younger than 20 years of age. The initial symptoms were a skeletal abnormality (71%), such as scoliosis (11 patients) or pes cavus (1 patient), pain or numbness (24%), and motor weakness (6%). Frequently seen signs on admission were sensory deficit (100%), scoliosis (85%), muscle weakness (64%), muscle atrophy (35%), and lower cranial nerve palsy (35%). The characteristic neurological findings were unilateral sensory and motor deficits (65%) with decreased or absent deep tendon reflexes on the same side. The localization of the syrinx on the axial section varied according to the level, even in the same patient. In 11 patients with unilateral sensory disturbances or unilateral sensory and motor deficits, the syrinx was located in the region corresponding to the posterolateral portion on the same side as that of sensory disturbance at the cervical or thoracic level. On the other hand, in 6 patients with bilateral sensory and motor deficits, the syrinx was located in the central portion and extended into the posterolateral portion of the more affected side. A syringosubarachnoid shunt was placed in 16 patients, foramen magnum decompression without closure of the obex was performed in 1 patient, ventriculoperitoneal shunt in 1 patient, terminal syringostomy in 1 patient, and foramen magnum decompression with terminal syringostomy in 1 patient. In 15 of 17 patients (88%), the neurological symptoms improved after an average follow-up of 4 years and 1 month. We think that as a surgical treatment, placement of a syringosubarachnoid shunt is effective.     

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.     

Nerve reconstruction in the hand and upper extremity

In the management of traumatic peripheral nerve injuries, the severity or degree of injury dictates the decision making between surgical management versus conservative management and serial examination. This review explores some of the recent literature, specifically addressing recent basic science advances in end-to-side and reverse end-to-side recovery, Schwann cell migration, and neuropathic pain. The management of nerve gaps, including the use of nerve conduits and acellularized nerve allografts, is examined. Current commonly performed nerve transfers are detailed with focus on both motor and sensory nerve transfers, their indications, and a basic overview of selected surgical techniques.     

The healing potential in cauda equina syndrome secondary to traumatic posterior L5-S1 dislocation. A case report with 16 years follow-up

Cauda equina syndrome is the result of any lesion that compresses or paralyzes cauda equina roots which are both motor and sensory. It is an uncommon syndrome, which features low back pain, sciatica, variable lower extremity motor and sensory loss with possible bladder and bowel dysfunction. It is an emergency situation as it may cause significant morbidity such as permanent paralysis, impaired bladder and/or bowel control or loss of sexual sensation. We present the case of a patient who was admitted to the emergency department with a traumatic posterior L5-S1 dislocation, low back pain and bladder dysfunction 8 days following an initial trauma. Open L5-S1 reduction and posterior stabilization was performed and the dural sac was decompressed. Most of the patient's neurological deficits resolved over several years, following the initial surgery.     

Phantom limb pain originates from dysfunction of the primary motor cortex

Accumulated knowledge indicates that phantom limb pain is a phenomenon of the central nervous system that is related to plastic changes at several levels of the nervous systems. Especially, reports using patients with neuropathic pain clearly indicate the sensorimotor cortex as underlying mechanisms of phantom limb and its pain. Here, we focus the notion that limb amputation or deafferentation results in plasticity of connections between the brain and the body, and that the cortical motor representation of the missing or deafferented limb seemingly disappears. Meanwhile, the sensory representation of the limb does not disappear and thereby patients feel phantom limbs. We propose that dissociation between motor and sensory representations in the primary motor cortex induces pathologic pain and reconcile of sensorimotor integration of the limb would alleviate pain, on the basis of our neurorehabilitation approaches and artificial neuromodulation strategies.     

Validation and the future of stimulation therapy of the primary motor cortex

The use of electrical motor cortex stimulation (EMCS) for post-stroke pain was established in Japan and has spread globally. EMCS has been used for the treatment of neuropathic pain, Parkinson's syndrome, and recovery of motor paresis. Since 2000, repetitive transcranial magnetic stimulation (rTMS) has been developed for the treatment of various neurological disorders. rTMS is a non-invasive method with almost no adverse effects. In the USA, rTMS of the left dorsolateral prefrontal cortex was approved for the treatment of major depression in 2008. rTMS of the primary motor cortex (M1) has been studied worldwide for the treatment of neuropathic pain, Parkinson's disease, motor paresis after stroke, and other neurological problems. New methods and devices for rTMS therapy are under development, and rTMS of the M1 is likely to be established as an effective therapy for some neurological disorders. The present review discusses EMCS and rTMS of the M1 concisely.     

Clinical presentation and physical examination

The main points to assimilate concerning the presentation of peripheral nerve tumors are their subtle features, few symptoms, and even fewer signs. It is no surprise that most lesions become apparent only when a mass becomes palpable. Pain, paresthesia, and a positive Tinel's sign are sometimes the only features, with the paresthesia being variable and unreliable as a clinical entity. Loss of profound sensory function and motor function is generally a late feature. When patients present with progressive pain and significant sensory and any motor deficits, these signs suggest that a more sinister lesion is present. It cannot be overstressed that the stigmata of neurocutaneous disorders should be sought in all patients with suspected peripheral nerve tumors. Similarly, the presence of such stigmata in a patient presenting with vague paresthetic symptoms in a nerve distribution should make the clinician suspect and investigate for an underlying nerve tumor.     

14 cases of communicating syringomyelia associated with Chiari I malformation in children]

The authors review their experience of 14 children with syringomyelia and associated Chiari I malformation observed during the last 21 years. Initial symptoms were motor weakness (57%), sensory signs (50%), scoliosis (50%) and bladder dysfunction (21.5%), while signs of admission were pyramidal signs (78.5%) with motor deficit (43%), spinal deformities (64.2%), syringomyelic syndrome (36%) and sensory deficit (21.5%). Four children were investigated with myelography, three with myelography and spinal CT Scan and the last seven cases with MRI. Ten children (71.4%) underwent a decompression of the Chiari malformation with or without drainage of the cyst and shunting of an associated hydrocephalus. Syringo-peritoneal shunts were used in 3 children and laminectomy with syringo-subarachnoid shunt in 1 case. The neurological symptoms improved in 57% of the cases, 2 patients deteriorated and 4 patients were lost to follow-up. The authors discuss the clinical symptomatology, the MRI study, the controversies concerning the treatment and concluded with their attitude concerning this pathology in children.     

Experience with gabapentin for neuropathic pain in adolescents: report of five cases

Summary Gabapentin is an antiepileptic drug indicated for the treatment of partial seizures in children. Many studies have proved its analgesic action in the treatment of neuropathic pain in adults and we have noticed an analgesic action of gabapentin in neuropathic pain in children. Five patients treated in the Children's Hospital Pain Control Service for intractable neuropathic pain were included in gabapentin treatment. Four were cancer patients and one suffered from neuropathic pain in the neck (C3). The visual analog scale (VAS) scores of pain were compared before and during treatment with gabapentin. We noticed a rapid improvement, in 1 week, of our patients' VAS scores (from 9 or 10 to 4 or 3) with minimal adverse effects. In the follow-up period of 6 months we gradually reduced the dose of gabapentin. Our findings are that gabapentin should be included earlier in the treatment of neuropathic pain in adolescents, because it rapidly improves analgesia and has minimal side effects.     

Behandlung des Morbus Sudeck

Complex regional pain syndrome (CRPS) was formerly known as “Sudeck’s atrophy”. The disease belongs to the group of neuropathic pain syndromes and is differentiated into three types. Type I is characterized by a lack of nerve lesions, type II by the presence of nerve lesions, and type III by the presence of other entities such as fibromyalgia. The exact pathogenic factors leading to the disease are still unknown and are currently the subject of investigation in various studies. These studies suggest a contribution of the central nervous system to the development and maintenance of CRPS. However, the clinical symptoms are well documented and include pain, autonomic changes and impaired motor function of the affected extremity. Diagnosis is based clinically on signs and symptoms. However, in a few cases radiography and scintiscanning may be useful to finalize the diagnosis. The treatment options are centred on the symptoms of pain, autonomic changes and functional impairment. A multidisciplinary treatment strategy is recommended, with surgeons, anaesthesiologists, physiotherapists and psychotherapists working together. Surgical intervention in this disease is only required in rare cases of neurological and bone pain, and the indications for such intervention are narrow and should be strictly observed.     

Does epidural analgesia delay the diagnosis of lower limb compartment syndrome in children?

One of the cardinal symptoms of compartment syndrome is pain. A literature review was undertaken in order to assess the association of epidural analgesia and compartment syndrome in children, whether epidural analgesia delays the diagnosis, and to identify patients who might be at risk. Evidence was sought to offer recommendations in the use of epidural analgesia in patients at risk of developing compartment syndrome of the lower limb. Increasing analgesic use, increasing/breakthrough pain and pain remote to the surgical site were identified as important early warning signs of impending compartment syndrome in the lower limb of a child with a working epidural. The presence of any should trigger immediate examination of the painful site, and active management of the situation (we have proposed one clinical pathway). Avoidance of dense sensory or motor block and unnecessary sensory blockade of areas remote to the surgical site allows full assessment of the child and may prevent any delay in diagnosis of compartment syndrome. Focusing on excluding the diagnosis of compartment syndrome rather than failure of analgesic modality is vital. In the pediatric cases reviewed there was no clear evidence that the presence of an epidural had delayed the diagnosis.     

When should conservative treatment for lumbar disc herniation be ceased and surgery considered?

Different authors recommend different time spans for conservative treatment before considering surgery in patients suffering from lumbar disc herniation. We analyzed the time of onset of symptoms such as pain, sensory deficit, and motor deficit in a surgically treated group in comparison to outcome after surgery in order to define a time threshold when surgical results deteriorate and operation should therefore be considered. General data, symptoms, signs, and neurological findings of 219 patients were preoperatively recorded. The outcome was evaluated according to the Prolo scale after a mean of 9.9 months. In the statistical workup, we calculated the duration of symptoms, sensory deficits, and motor deficit as continuous variables. Additionally, the population was divided into three groups of duration of symptoms, sensory deficit, or motor deficit for ≤30 days, 30–60 days, and >60 days. Statistically significant predictors for unfavourable outcome were, for example, a longer duration of preoperative pain and motor and sensory deficit. Patients suffering for more than 60 days from disc herniation were found to have statistically worse outcome than patients suffering for 60 days or less. Findings were similar for the different time groups concerning the duration of sensory deficit but not for duration of motor deficit. The overall outcome seems to be better when patients are operated on for lumbar disc herniations within 2 months after onset of symptoms and sensory deficits. Due to these findings, we recommend conservative treatment up to 2 months and, if conservative management does not succeed, consideration of surgery. Electronic Publication     

Treatment of transected peripheral nerves with artemin improved motor neuron regeneration,but did not reduce nerve injury-induced pain behaviour

Incomplete recovery of function and neuropathic pain are common problems after peripheral nerve injury. To develop new treatment strategies for peripheral nerve injuries we investigated whether the neurotrophic factor artemin could improve outcome after sciatic nerve injuries in rats. Artemin is a member of the glial cell line-derived neurotrophic factor (GDNF) family and exerts neuroprotective effects on sensory neurons as well as influencing behavioural thermal sensitivity. We additionally evaluated if fibrin sealant, which is sometimes used as a nerve glue, had any effects on neuropathic pain-related behaviour. After the sciatic nerve had been transected, 30 animals were randomised to one of three groups: treatment with a fibrin sealant that contained artemin in conjunction with sutures; fibrin sealant with no artemin (sham) in conjunction with sutures; or sutures alone (n=10 in each group). Motor function, sensory function, and autotomy were evaluated from 1 to 12 weeks after injury. Retrograde flourogold tracing 12 weeks after injury showed that the addition of artemin increased the number of regenerating motor neurons. However, it did not improve their performance, as measured by the Sciatic Function Index, compared with sham or suture alone. Animals treated with artemin had a non-significant increase in motor nerve conduction velocity compared with sham. However, artemin did not reverse nerve injury-induced pain behaviour such as cold or heat hypersensitivity. Fibrin sealant in itself did not ameliorate motor performance, or regeneration of motor neurons, or give rise to nerve injury-induced pain behaviour. The results indicate that artemin is of value as a treatment for peripheral nerve injuries, although the effects were limited. As the artemin high-affinity receptor GFRα-3 is present in Schwann cells and not in motor neurons, the effect on motor neuron axon regeneration may result from an indirect effect through Schwann cells in the injured nerve.     

Evaluation of Pain Measurement Practices and Opinions of Peripheral Nerve Surgeons

The purpose of this study was to evaluate the opinions and practices of peripheral nerve surgeons regarding assessment and treatment of pain in patients following nerve injury. Surgeons with expertise in upper extremity peripheral nerve injuries and members of an international peripheral nerve society were sent an introductory letter and electronic survey by email (n = 133). Seventy members responded to the survey (49%) and 59 surgeons completed the survey (44%). For patients referred for motor or sensory dysfunction, 31 surgeons (52%) indicated that they always formally assess pain. In patients referred for pain, 44 surgeons (75%) quantitatively assess pain using a verbal scale (n = 24) or verbal numeric scale (n = 36). The most frequent factors considered very important in the development of chronic neuropathic pain were psychosocial factors (64%), mechanism of injury (59%), workers’ compensation or litigation (54%), and iatrogenic injury (48%). In patients more than 6 months following injury, surgeons frequently see: cold sensitivity (54%), decreased motor function (42%), paraesthesia or numbness (41%), fear of returning to work (22%), neuropathic pain (20%), and emotional or psychological distress (17%). Only 52% of surgeons who responded to the survey always evaluate pain in patients referred for motor or sensory dysfunction. Pain assessment most frequently includes verbal patient response, and assessment of psychosocial factors is rarely included. Predominately, patient-related factors were considered important in the development of chronic neuropathic pain.     

Varied presentations of cervical spondylotic myelopathy presenting to a chiropractic clinic: a report of 3 cases

Cervical spondylotic myelopathy (CSM) is the leading cause of acquired spinal cord dysfunction worldwide and may be expected to increase in prevalence due to an aging global population. Clinical features of CSM are highly variable, and chiropractors frequently manage patients with common signs and symptoms of CSM such as neck pain, extremity weakness, and gait imbalances. Early recognition of signs consistent with myelopathy may mitigate future disability and improve quality of life. Key predictors of patient outcome are the age of initial presentation, baseline CSM severity (as measured by mJOA score), and the presence of gait disturbances. This report describes three cases of CSM presenting to a chiropractic clinic. Each case illustrates a unique manifestation of CSM, including myelopathy, myeloradiculopathy, and distal neuropathic pain (funicular referral). In addition, a review of CSM terminology, epidemiology, pathobiology, clinical features, imaging, and management is provided.