Psychological factors and trajectories of post-surgical pain: A longitudinal prospective study.

A significant proportion of patients do not experience relief from pain during the early postsurgical period after joint arthroplasty and are at risk for developing chronic pain. The objectives of this study were to identify biopsychosocial factors associated with acute postsurgical pain trajectories and with pain intensity and interference after 1, 3, and 12 months. Two hundred ten patients listed for joint arthroplasty filled a presurgical battery of questionnaires assessing presurgical pain intensity, catastrophizing, emotional distress, state anxiety and depression, self-efficacy, central sensitization, and executive functions. From the day after surgery, they were asked to fill a 7-day diary, including questions about postsurgical pain and postsurgical state catastrophizing. Finally, they provided data about pain intensity and interference after 1, 3, and 12 months. Predictors of acute pain trajectories were investigated using multilevel growth curve analysis. Results showed that central sensitization was a predictor of the intercept of pain trajectories and daily postsurgical catastrophizing was a significant covariate of pain intensity in the acute phase. Analyses of follow-up data showed that central sensitization was a predictor of pain intensity and pain interference at 3 and 12 months, that emotional distress was related with pain intensity and interference at 1 month, and with pain interference at 3 months, and that cognitive flexibility was associated with pain interference at 1 month. Assessment of these factors could enable to identify patients at risk for worse outcomes and to plan targeted treatments to be implemented during the patient's inward stay.

Psychological and psychosocial predictors of chronic postsurgical pain: a systematic review and meta-analysis.

Knowledge about psychological and psychosocial predictors of chronic postsurgical pain is important to identify patients at risk for poor outcomes. The objective of this systematic review with meta-analysis was to assess the effect of such predictors. A comprehensive search of the available literature on this topic was performed using the electronic databases PubMed, Scopus, Embase, and PsycInfo. Estimates of the effect of each predictor were extracted, and both a narrative synthesis and a quantitative synthesis of these estimates were performed. Multiple imputation was used to take into account the effect of nonsignificant estimates in case they were not reported by original studies. From a sample of 8322 records, 83 articles were included in the narrative synthesis and 41 studies were used to perform the meta-analyses. The narrative synthesis showed that evidence about the effect of psychological predictors is heterogeneous, with few expected predictors, such as optimism, state anxiety and psychological distress, consistently associated with chronic postsurgical pain. By contrast, the meta-analyses showed that state anxiety, trait anxiety, mental health, depression, catastrophizing and, to a lesser extent, kinesiophobia and self-efficacy have a weak but significant association with chronic postsurgical pain. In conclusion, this study showed that psychological predictors have a significant association with chronic postsurgical pain and that state anxiety is the most explicative one.

Altered Interoceptive Perception and the Effects of Interoceptive Analgesia in Musculoskeletal, Primary, and Neuropathic Chronic Pain Conditions.

Chronic pain (CP) severely disrupts the daily life of millions. Interoception (i.e., sensing the physiological condition of the body) plays a pivotal role in the aetiology and maintenance of CP. As pain is inherently an interoceptive signal, interoceptive frameworks provide important, but underutilized, approaches to this condition. Here we first investigated three facets of interoceptive perception in CP, compared with pain-free controls. We then introduce a novel interoceptive treatment and demonstrate its capacity to reduce pain severity in CP, potentially providing complementary analgesic treatments. Study 1 measured interoceptive accuracy, confidence and sensibility in patients (N = 60) with primary, secondary musculoskeletal, and neuropathic CP. Compared with matched controls, CP participants exhibited significantly lower interoceptive accuracy and interoceptive confidence. Pain severity was predicted positively by interoceptive accuracy, anxiety and depression, and negatively by interoceptive confidence. Study 2 tested a promising new interoceptive treatment for CP, in a single-blind between-subjects design (N = 51) with primary, secondary musculoskeletal, and neuropathic CP patients. The treatment specifically activates the C-Tactile system, by means of controlled stimulation of interoceptive unmyelinated afferents, at 3 cm/s with a force of 2.5 mN. This treatment led to significant pain reduction (mean 23%) in the CP treatment group after only 11 min, while CP controls who received comparable but non-interoceptive stimulation reported no change in pain intensity. These studies highlight the importance of interoceptive approaches to CP and demonstrate the potential of this novel method of C-Tactile stimulation to provide complementary analgesic treatments.

The Predictive Role of Executive Functions and Psychological Factors on Chronic Pain after Orthopaedic Surgery: A Longitudinal Cohort Study.

Prevention and treatment of chronic post-surgical pain should be based on the early identification of patients at risk. The presence of a deficit in executive functions, along with the presence of psychological risk factors, could impair the use of appropriate pain coping strategies and might facilitate the transition to chronic post-surgical pain. A longitudinal cohort study was implemented. Patients listed for orthopaedic surgery were enrolled. Variables measured before surgery were pain intensity, the sensory, affective, cognitive and mixed components of pain, state and trait variables associated with the psychological status of the patient, fear of movement, pain catastrophizing, visual attention and cognitive flexibility. Pain intensity and the components of pain were re-evaluated after surgery and after three months. A linear mixed model was used to assess the predictors of pain intensity, and a multivariate linear mixed model was used to assess the predictors of the pain components. 167 patients were enrolled. Controlling for sex, age, pain duration and surgical procedure, catastrophizing and visual attention were predictors of pain intensity at follow-up. The sensory component of pain was predicted by state anxiety, healthcare-related fears, pain catastrophizing and visual attention. Anxiety and catastrophizing were predictors of the affective and evaluative components of pain. The mixed component of pain was predicted by state anxiety, healthcare-related fears and pain catastrophizing. Executive functions, along with psychological risk factors, shape the course of post-surgical pain. The efficacy of preventive and rehabilitation treatment could be possibly enhanced if these factors are treated.

What Is the Role of the Placebo Effect for Pain Relief in Neurorehabilitation? Clinical Implications From the Italian Consensus Conference on Pain in Neurorehabilitation.

BACKGROUND: It is increasingly acknowledged that the outcomes of medical treatments are influenced by the context of the clinical encounter through the mechanisms of the placebo effect. The phenomenon of placebo analgesia might be exploited to maximize the efficacy of neurorehabilitation treatments. Since its intensity varies across neurological disorders, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCP) summarized the studies on this field to provide guidance on its use. METHODS: A review of the existing reviews and meta-analyses was performed to assess the magnitude of the placebo effect in disorders that may undergo neurorehabilitation treatment. The search was performed on Pubmed using placebo, pain, and the names of neurological disorders as keywords. Methodological quality was assessed using a pre-existing checklist. Data about the magnitude of the placebo effect were extracted from the included reviews and were commented in a narrative form. RESULTS: 11 articles were included in this review. Placebo treatments showed weak effects in central neuropathic pain (pain reduction from 0.44 to 0.66 on a 0-10 scale) and moderate effects in postherpetic neuralgia (1.16), in diabetic peripheral neuropathy (1.45), and in pain associated to HIV (1.82). Moderate effects were also found on pain due to fibromyalgia and migraine; only weak short-term effects were found in complex regional pain syndrome. Confounding variables might have influenced these results. CLINICAL IMPLICATIONS: These estimates should be interpreted with caution, but underscore that the placebo effect can be exploited in neurorehabilitation programs. It is not necessary to conceal its use from the patient. Knowledge of placebo mechanisms can be used to shape the doctor-patient relationship, to reduce the use of analgesic drugs and to train the patient to become an active agent of the therapy.

Real life evaluation of safinamide effectiveness in Parkinson's disease.

In this retrospective study, we evaluated both efficacy and effectiveness of safinamide 50 and 100 mg in the treatment of motor fluctuations and disabling dyskinesias in a cohort of patients with idiopathic Parkinson's disease (PD). Ninety-one PD patients were evaluated during the first year of commercialization of the drug, both prior to starting safinamide and at the last available follow-up. Evaluations were based on the Unified Parkinson's Disease Scale part III (UPDRS III), Hoehn & Yahr (HY), Unified Dyskinesia Rating Scale (UDysRS) walking and balance item 9 score, daily time spent in OFF and in ON with disabling dyskinesias (1 week diary), mean daily dose of levodopa (LD), dopamine-agonists (DA), catechol-O-methyl transferase inhibitor (COMT-I), monoamine oxidase B inhibitor (MAOB-I), and their LD equivalent dose (LEDD). Eight patients withdrew safinamide within the first month for minor side effects. At the follow-up evaluation, after a mean time with safinamide of 7.5 months ± 3.4, all patients showed a significant improvement of all the scale scores, except for HY, and of the daily dosages of the drugs and the LEDD. The same results were shown by PD patients treated with safinamide 50 mg and patients who started safinamide without switching from a previous MAOBI. PD patients with safinamide 100 mg and patients who started safinamide switching from a previous MAOBI significantly improved in time spent in OFF and LEDD. In conclusion, safinamide is safe and effective in improving motor complications in patients with idiopathic PD and can be considered a useful levodopa sparing strategy.

Diagnostic accuracy of laser-evoked potentials in diabetic neuropathy.

Although the most widely agreed neurophysiological tool for investigating small fiber damage is laser-evoked potential (LEP) recording, no study has documented its diagnostic accuracy. In this clinical, neurophysiological, and skin biopsy study, we collected age-corrected LEP normative ranges, verified the association of LEPs with pinprick sensory disturbances in the typical diabetic mixed fiber polyneuropathy, and assessed the sensitivity and specificity of LEPs in diabetic small fiber neuropathy. From 288 LEP recordings from the face, hand, and foot in 73 healthy subjects, we collected age-corrected normative ranges for LEPs. We then selected 100 patients with mixed-fiber diabetic neuropathy and 25 patients with possible small-fiber diabetic neuropathy. In the 100 patients with mixed fiber neuropathy, we verified how LEP abnormalities were associated with clinically evident pinprick sensory disturbances. In the 25 patients with possible pure small fiber neuropathy, using the skin biopsy for assessing the intraepidermal nerve fiber density as a reference standard, we calculated LEP sensitivity and specificity. In healthy participants, age strongly influenced normative ranges for all LEP variables. By applying age-corrected normative ranges for LEPs, we found that LEPs were strongly associated with pinprick sensory disturbances. In relation to the skin biopsy findings, LEPs yielded 78% sensitivity and 81% specificity in the diagnosis of diabetic small fiber neuropathy. Our study, providing age-corrected normative ranges for the main LEP data and their diagnostic accuracy, helps to make LEPs more reliable as a clinical diagnostic tool, and proposes this technique as a less invasive alternative to skin biopsy for diagnosing diabetic small fiber neuropathy.

Delayed Gastric Emptying in Advanced Parkinson Disease: Correlation With Therapeutic Doses.

INTRODUCTION: Gastrointestinal dysfunction is often described in patients with Parkinson disease (PD), and gastrointestinal symptoms are usually attributed to gastroparesis. The consequent delayed gastric emptying (GE) may be an important pharmacokinetic mechanism underlying some of the response fluctuations that develop after long-term levodopa (L-dopa) therapy.The aim of this prospective study was to assess GE time by a liquid meal scintigraphy, in PD patients, and to correlate them with demographic, clinical, and therapeutic data. METHODS: Scintigraphy with radiolabeled albumin nanocolloids added to acidified orange juice was performed in 51 consecutive PD patients 1 hour after their usual dopaminergic therapy first dose and after a 12-hour fast. Demographic, neurologic, gastrointestinal, and pharmacologic data were collected. RESULTS: Fifty-one patients were divided into 2 groups using the cutoff point obtained in normal subjects (40 minutes): group 1 included 29 patients with GE T½ of 27.60 ± 7.30 minutes (normal), group 2 showed a GE T½ of 84.90 ± 53.80 minutes (delayed). The most striking significant difference between the 2 groups was the dopa-decarboxylase inhibitor mean dose that was significantly higher in the group of patients with delayed GE (201.32 ± 97.26 vs 127.65 ± 79.74; P = 0.005). CONCLUSIONS: The impairment of gastric motility, frequently represented in PD patients, occurs in approximately 42% of patients with motor complications. A mechanism that may explain the GE delay is the effect of L-dopa on dopaminergic receptors in the stomach. Therefore, the dosage of dopa-decarboxylase inhibitor, increasing the L-dopa concentration, may contribute to GE delay and its consequent effect on drug delivery and efficacy.

Pharmacological and non-pharmacological strategies in the integrated treatment of pain in neurorehabilitation. Evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

The interplay between pain and neurorehabilitation is very complex, in that pain may be a target for treatment, but can also have negative effects on neurorehabilitation procedures. Moreover, side effects of drugs, which are currently used to treat pain, may negatively influence rehabilitation outcomes. Because of the lack of guidelines or consensus, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) was aimed to answer some open questions on the treatment of pain in this setting. To this aim, we collected evidence on the pharmacological and non-pharmacological strategies and their role in the integrated approach to pain. Despite the lack of studies in patients undergoing neurorehabilitation, current guidelines on the pharmacological treatment of nociceptive and neuropathic pain may be applied in this setting. Non-pharmacological strategies include physical therapy, invasive procedures, psychological treatments and psychotherapy, which together with pharmacological therapies play a key role in the integrated approach to pain. The ICCPN recommendations offer information to ameliorate the current treatment of pain in neurorehabilitation, and to design future studies to answer the still open questions on this topic.

Psychological Considerations in the Assessment and Treatment of Pain in Neurorehabilitation and Psychological Factors Predictive of Therapeutic Response: Evidence and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

BACKGROUND: In order to provide effective care to patients suffering from chronic pain secondary to neurological diseases, health professionals must appraise the role of the psychosocial factors in the genesis and maintenance of this condition whilst considering how emotions and cognitions influence the course of treatment. Furthermore, it is important not only to recognize the psychological reactions to pain that are common to the various conditions, but also to evaluate how these syndromes differ with regards to the psychological factors that may be involved. As an extensive evaluation of these factors is still lacking, the Italian Consensus Conference on Pain in Neurorehabilitation (ICCPN) aimed to collate the evidence available across these topics. OBJECTIVES: To determine the psychological factors which are associated with or predictive of pain secondary to neurological conditions and to assess the influence of these aspects on the outcome of neurorehabilitation. METHODS: Two reviews were performed. In the first, a PUBMED search of the studies assessing the association between psychological factors and pain or the predictive value of these aspects with respect to chronic pain was conducted. The included papers were then rated with regards to their methodological quality and recommendations were made accordingly. In the second study, the same methodology was used to collect the available evidence on the predictive role of psychological factors on the therapeutic response to pain treatments in the setting of neurorehabilitation. RESULTS: The first literature search identified 1170 results and the final database included 189 articles. Factors such as depression, anxiety, pain catastrophizing, coping strategies, and cognitive functions were found to be associated with pain across the various conditions. However, there are differences between chronic musculoskeletal pain, migraine, neuropathy, and conditions associated with complex disability with regards to the psychological aspects that are involved. The second PUBMED search yielded 252 studies, which were all evaluated. Anxiety, depression, pain catastrophizing, coping strategies, and pain beliefs were found to be associated to different degrees with the outcomes of multidisciplinary programs, surgery, physical therapies, and psychological interventions. Finally, sense of presence was found to be related to the effectiveness of virtual reality as a distraction tool. CONCLUSIONS: Several psychological factors are associated with pain secondary to neurological conditions and should be acknowledged and addressed in order to effectively treat this condition. These factors also predict the therapeutic response to the neurorehabilitative interventions.

Psychological Treatments and Psychotherapies in the Neurorehabilitation of Pain: Evidences and Recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation.

BACKGROUND: It is increasingly recognized that treating pain is crucial for effective care within neurological rehabilitation in the setting of the neurological rehabilitation. The Italian Consensus Conference on Pain in Neurorehabilitation was constituted with the purpose identifying best practices for us in this context. Along with drug therapies and physical interventions, psychological treatments have been proven to be some of the most valuable tools that can be used within a multidisciplinary approach for fostering a reduction in pain intensity. However, there is a need to elucidate what forms of psychotherapy could be effectively matched with the specific pathologies that are typically addressed by neurorehabilitation teams. OBJECTIVES: To extensively assess the available evidence which supports the use of psychological therapies for pain reduction in neurological diseases. METHODS: A systematic review of the studies evaluating the effect of psychotherapies on pain intensity in neurological disorders was performed through an electronic search using PUBMED, EMBASE, and the Cochrane Database of Systematic Reviews. Based on the level of evidence of the included studies, recommendations were outlined separately for the different conditions. RESULTS: The literature search yielded 2352 results and the final database included 400 articles. The overall strength of the recommendations was medium/low. The different forms of psychological interventions, including Cognitive-Behavioral Therapy, cognitive or behavioral techniques, Mindfulness, hypnosis, Acceptance and Commitment Therapy (ACT), Brief Interpersonal Therapy, virtual reality interventions, various forms of biofeedback and mirror therapy were found to be effective for pain reduction in pathologies such as musculoskeletal pain, fibromyalgia, Complex Regional Pain Syndrome, Central Post-Stroke pain, Phantom Limb Pain, pain secondary to Spinal Cord Injury, multiple sclerosis and other debilitating syndromes, diabetic neuropathy, Medically Unexplained Symptoms, migraine and headache. CONCLUSIONS: Psychological interventions and psychotherapies are safe and effective treatments that can be used within an integrated approach for patients undergoing neurological rehabilitation for pain. The different interventions can be specifically selected depending on the disease being treated. A table of evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation is also provided in the final part of the paper.

The cognitive and behavioural profile of amyotrophic lateral sclerosis: application of the consensus criteria.

OBJECTIVE: The study aims to assess the spectrum of cognitive and behavioural disorders in patients affected by Amyotrophic Lateral Sclerosis (ALS) according to the recent consensus criteria [9]. The study also intends to assess the impact of physical disability on cognitive and behavioural abnormalities. METHODS: Detailed neurological, neuropsychological and neurobehavioral evaluations were administered to 23 ALS patients, 11 Lower Motor Neuron Disease (LMND) patients and 39 healthy controls. Strong et al.'s criteria [9] were applied to diagnose the presence of cognitive/behavioural impairment. Clinical and neuropsychological scores were used for group comparisons and correlation analyses. RESULTS: In comparison with LMND and controls, a subgroup of ALS patients (∼30%) manifested executive dysfunction, which was severe enough to classify them as cognitively impaired. Action naming difficulties and short-term memory deficits were also observed. Aspontaneity, disorganization and mental rigidity reached clinical relevance in 20% of ALS patients. A small percentage of ALS patients (13%) also had comorbid dementia. The cognitive or behavioural status was not related to the clinical features of ALS. CONCLUSION: The use of consensus criteria for cognitive and behavioural impairment and the comparison with the LMND group proved useful in defining the spectrum of non-motor manifestations of ALS.

Antineuropathic and antinociceptive drugs combination in patients with chronic low back pain: a systematic review.

Purpose. Chronic low back pain (LBP) is often characterized by both nociceptive and neuropathic components. While various monotherapies have been reported of only limited efficacy, combining drugs with different mechanisms of action and targets appears a rational approach. Aim of this systematic review is to assess the efficacy and safety of different combined pharmacological treatments, compared to monotherapy or placebo, for the pharmacological treatment of chronic LBP. Methods. Published papers, written or abstracted in English from 1990 through 2011, comparing combined pharmacological treatments of chronic LBP to monotherapy or placebo were reviewed. Results. Six articles met the inclusion criteria. Pregabalin combined with celecoxib or opioids was shown to be more effective than either monotherapy. Oxycodone-paracetamol versus previous treatments and tramadol-paracetamol versus placebo were also reported as effective, while morphine-nortriptyline did not show any benefit over any single agent. Conclusions. In spite of theoretical advantages of combined pharmacological treatments of chronic LBP, clinical studies are remarkably few. Available data show that combined therapy, including antinociceptive and antineuropathic agents is more effective than monotherapy, with similar side effects.

Painful diabetic polyneuropathy: approach to diagnosis and management.

OBJECTIVES: To provide a current overview of the diagnostic work-up and management of painful diabetic polyneuropathy (PDPN). METHODS: A review covering the literature from 2004 to 2011, which describes the tools designed to diagnose neuropathic pain and assess its severity, including self-administered questionnaires, validated laboratory tests and simple handheld screening devices, and the evidence-based therapeutic approaches to PDPN. RESULTS: The clinical aspects, pathogenesis, and comorbidities of PDPN, as well as its impact on health related quality of life (HR-QoL), are the main drivers for the management of patients with suspected PDPN. PDPN treatment consists first of all in improving glycemic control and lifestyle intervention. A number of symptomatic pharmacological agents are available for pain control: tricyclic antidepressants and selective serotonin norepinephrine reuptake inhibitors (venlafaxine and duloxetine), α2-delta ligands (gabapentin and pregabalin), opioid analgesics (tramadol and oxycodone), and agents for topical use, such as lidocaine patch and capsaicin cream. With the exception of transcutaneous electrical nerve stimulation, physical treatment is not supported by adequate evidence. DISCUSSION: As efficacy and tolerability of current therapy for PDPN are not ideal, the need for a better approach in management further exists. Novel compounds should be developed for the treatment of PDPN.

The Lindblom roller.

Neuropathic pain is caused by injury of the peripheral or central nervous system. The neurological examination of the sensory system in neuropathic pain patients guides the anatomical localization of the injury. Among the sensory modalities to be tested, priority should be given to those subserved by small peripheral sensory fibers or by the spinothalamic tract that most commonly are abnormal in neuropathic pain patients. Testing of cold and warm perception was traditionally carried out in the clinic using tubes filled with water at different temperatures, a cumbersome method that has limited the routine examination of these sensory modalities. The Lindblom roller offers a practical and effective method of readily testing temperature perception and is among the best available clinical tools for delineating the anatomical boundaries of a sensory abnormality. Routinely use of the Lindblom roller shall be standard bedside clinical assessment of neuropathic pain patients. To exemplify this statement we describe two patients affected by complex and fluctuating painful sensory abnormalities caused by an extradural mass compressing the spinal cord. The level of the injury was readily localized with a roller kept at room temperature.

Pre-injury lidocaine treatment prevents thermal hyperalgesia and cutaneous thermal abnormalities in a rat model of peripheral neuropathy.

The effect of lidocaine pretreatment on thermal hyperalgesia and thermal skin asymmetries provoked by experimental mononeuropathy was investigated in rats. Forty anesthetized rats were given sciatic nerve ligatures according to the technique of Bennett and Xie. Rats were divided into 3 groups: 16 were ligated without lidocaine, 16 were ligated after lidocaine bathing of the nerve, and 8 were ligated after systemic lidocaine (6-8 mg/kg). Six sham-operated rats for each group were also prepared. From the first postoperative day the responses to the hot-plate test were assessed daily for 4 weeks by tracking the paw-licking latency (PLL) for both hindpaws. Shorter or longer latencies on the operated side were respectively considered sign of hyperalgesia and hypoalgesia. Infrared thermographic images of plantar hindpaws were taken in 22 operated rats in the 2nd postoperative week. Thermographic images of 8 non-operated rats were used as control. Animals operated without lidocaine exhibited shorter PLL (P < 0.001) and a decreased skin temperature on the operated side (P < 0.001). In the lidocaine-pretreated rats, no paw-licking reflex was present for a variable postoperative period (1 week or more) and afterwards there was a trend toward recovery of normal PLL values at the 4th week; the hindpaw skin temperature was symmetrical and normal. Sham-operated rats had normal tests. It is postulated here that lidocaine prevents behavioral and thermal manifestation of mononeuropathy by blocking early afferent injury barrage.

Lidocaine test in neuralgia.

Ten patients with organic nerve injury causing chronic neuropathic pain were tested for the effects of intravenous lidocaine versus saline upon psychophysical somatosensory variables. The variables assessed were the subjective magnitude of pain, area of mechanical hyperalgesia and presence and magnitude of thermal heat/cold hyperalgesia. The study methods applied to evaluate these conditions were the conventional testing of somatosensory submodalities with area mapping and the subjective magnitude estimation of spontaneous pain. It was found that spontaneous pain and mechanical hyperalgesia were consistently improved, transiently, by intravenous administration of lidocaine in all 10 patients; areas of hyperalgesia which extended beyond the territory of the nerve also improved transiently. Spontaneous pain and mechanical hyperalgesia, but not hypoesthesia, were transiently improved by injection of saline in only 1 of the 10 patients. This outcome is probably due to a placebo effect. This improvement is in keeping with the inhibition of anomalous neural impulses which can be generated anywhere along the sensory channels responsible for generating spontaneous pain and hyperalgesia. Thus, intravenous lidocaine is proposed as a diagnostic aid in the examination of patients complaining of complex sensory disorders associated with nerve injury. The transient pain relief may allow a fuller identification of the area of sensory loss.