The Computerized General Neuropsychological INPH Test revealed improvement in idiopathic normal pressure hydrocephalus after shunt surgery

OBJECTIVE

The Computerized General Neuropsychological INPH Test (CoGNIT) provides the clinician and the researcher with standardized and accessible cognitive assessments in patients with idiopathic normal pressure hydrocephalus (INPH). CoGNIT includes tests of memory, executive functions, attention, manual dexterity, and psychomotor speed. Investigations of the validity and reliability of CoGNIT have been published previously. The aim of this study was to evaluate CoGNIT's sensitivity to cognitive change after shunt surgery in patients with INPH.

METHODS

Forty-one patients with INPH (median Mini-Mental State Examination score 26) were given CoGNIT preoperatively and at a postoperative follow-up 4 months after shunt surgery. Scores were compared to those of 44 healthy elderly control volunteers. CoGNIT was administered by either a nurse or an occupational therapist.

RESULTS

Improvement after shunt surgery was seen in all cognitive domains: memory (10-word list test, p < 0.01); executive functions (Stroop incongruent color and word test, p < 0.01); attention (2-choice reaction test, p < 0.01); psychomotor speed (Stroop congruent color and word test, p < 0.01); and manual dexterity (4-finger tapping, p < 0.01). No improvement was seen in the Mini-Mental State Examination score. Preoperative INPH test scores were significantly impaired compared to healthy control subjects (p < 0.001 for all tests).

CONCLUSIONS

In this study the feasibility for CoGNIT to detect a preoperative impairment and postoperative improvement in INPH was demonstrated. CoGNIT has the potential to become a valuable tool in clinical and research work.Clinical trial registration no.: NCT01618500 (clinicaltrials.gov).

Vascular risk factors in INPH: A prospective case-control study (the INPH-CRasH study)

OBJECTIVE

To assess the complete vascular risk factor (VRF) profile of idiopathic normal pressure hydrocephalus (INPH) using a large sample of representative patients with INPH and population-based controls to determine the extent to which vascular disease influences INPH pathophysiology.

METHODS

All patients with INPH who underwent shunting in Sweden in 2008-2010 were compared to age- and sex-matched population-based controls. Inclusion criteria were age 60-85 years and no dementia. The 10 most important VRFs and cerebrovascular and peripheral vascular disease were prospectively assessed using blood samples, clinical examinations, and standardized questionnaires. Assessed VRFs were hypertension, hyperlipidemia, diabetes, obesity, psychosocial factors, smoking habits, diet, alcohol intake, cardiac disease, and physical activity.

RESULTS

In total, 176 patients with INPH and 368 controls participated. Multivariable logistic regression analysis indicated that hyperlipidemia (odds ratio [OR] 2.380; 95% confidence interval [CI] 1.434-3.950), diabetes (OR 2.169; 95% CI 1.195-3.938), obesity (OR 5.428; 95% CI 2.502-11.772), and psychosocial factors (OR 5.343; 95% CI 3.219-8.868) were independently associated with INPH. Hypertension, physical inactivity, and cerebrovascular and peripheral vascular disease were also overrepresented in INPH. Moderate alcohol intake and physical activity were overrepresented among the controls. The population-attributable risk percentage was 24%.

CONCLUSIONS

Our findings confirm that patients with INPH have more VRFs and lack the protective factors present in the general population. Almost 25% of cases of INPH may be explained by VRFs. This suggests that INPH may be a subtype of vascular dementia. Targeted interventions against modifiable VRFs are likely to have beneficial effects on INPH.

Preoperative and postoperative 1H-MR spectroscopy changes in frontal deep white matter and the thalamus in idiopathic normal pressure hydrocephalus

BACKGROUND

In a previous study we found significantly decreased N-acetyl aspartate (NAA) and total N-acetyl (tNA) groups in the thalamus of patients with idiopathic normal pressure hydrocephalus (iNPH) compared with healthy individuals (HI). No significant difference between the groups could be found in the frontal deep white matter (FDWM).

OBJECTIVE

The primary aim of this study was to investigate if these metabolites in the thalamus were normalised after shunt surgery. The secondary aim was to investigate postoperative metabolic changes in FDWM.

SUBJECTS AND METHODS

Fourteen patients with iNPH, mean age 74 years, and 15 HI, also mean age 74 years, were examined. Assessment of a motor score (MOSs) was performed before and after shunt surgery. Absolute quantitative (1)H-MR spectroscopy (1.5 T, volumes of interest 2.5-3 ml) was performed on the patients in the FDWM and in the thalamus, before and 3 months after shunt surgery, and also once on the HI. The following metabolites were analysed: tNA, NAA, total creatine, total choline (tCho), myo-inositol (mIns), glutamate and lactate concentrations. MRI volumetric calculations of the lateral ventricles were also performed.

RESULTS

At 3 months postoperatively, we found no significant changes of tNA or NAA in the thalamus. In contrast, in the FDWM, there was a significant increase of tCho (p=0.01) and a borderline significant decrease of mIns (p=0.06). 12/14 patients were shunt responders (motor function). Median reduction of the lateral ventricle was 16%. A weak correlation between MOS and ventricular reduction was seen.

CONCLUSIONS

Normalisation of thalamic tNA and NAA could not be detected postoperatively. The increased tCho and decreased mIns in the FDWM postoperatively might relate to clinical improvement.

Implementation of a new CSF dynamic device: a multicenter feasibility study in 562 patients

OBJECTIVES

The cerebrospinal fluid (CSF) infusion test is frequently used when selecting hydrocephalus patients for shunt surgery. Very little has been reported regarding adverse events. We present a prospective feasibility study.

METHODS

Standardized devices for measuring CSF dynamics were built and 562 patients investigated: Needles were placed by lumbar puncture (LP). An automatic CSF infusion protocol was performed. Course of events during the investigation as well as adverse events were registered.

RESULTS

Preoperative evaluation of normal-pressure hydrocephalus was the most common indication (63%), followed by evaluation of shunt function (23%) and intracranial pressure recordings (14%). The LP was successfully performed in all but nine cases with 24 patients (4.3%) reporting major discomfort. Ringer infusion was performed in 474 investigations, and a valid measurement of the outflow resistance was received in 439 (93%). During the infusion phase, 17 (4%) patients reported severe headache. Infusion volume was significantly higher in patients having subjective symptoms during the infusion phase compared with those without adverse events. During 269 preoperative CSF tap tests, six (2%) patients had severe headache. Post-investigational headache was reported by 83 (15%) patients at the 24-h follow-up. No serious adverse events were observed.

CONCLUSION

Infusion testing was safe and without serious adverse events with a high rate of successful procedures. The investigation was associated with expected mild to moderate discomfort.

Reduced thalamic N-acetylaspartate in idiopathic normal pressure hydrocephalus: a controlled 1H-magnetic resonance spectroscopy study of frontal deep white matter and the thalamus using absolute quantification

INTRODUCTION

Patients with idiopathic normal pressure hydrocephalus (INPH) frequently have a reduction in cerebral blood flow in the subcortical frontal lobe/basal ganglia/thalamic areas. With magnetic resonance spectroscopy, the metabolism in the brain can be examined. The aim of this study was to investigate if there was a compromised metabolism in the thalamus and in the subcortical frontal areas in INPH patients. This was done by measuring total creatine, myo-inositol, total choline, N-acetylaspartate (NAA), total N-acetylaspartate (tNA), glutamate and lactate levels. A comparison was made with healthy individuals (HI).

SUBJECTS AND METHODS

16 patients (nine males, seven females, mean age 74 years, range 49-83) diagnosed as INPH and 15 HI (nine males, six females, mean age 74 years, range 62-89) were examined. (1)H magnetic resonance spectroscopy (1.5 T, point-resolved spectroscopy, echo time/relaxation time 30/3000 ms, volume of interest 2.5-3 ml) was performed in frontal deep white matter and in the thalamus. Absolute quantification with internal water as a reference was used.

RESULTS

INPH patients had lower NAA (p=0.02) and lower tNA (p=0.05) concentrations in the thalamus compared with HI. NAA and tNA in the frontal deep white matter did not differ between patients and HI. The absolute metabolic concentrations of total creatine, myo-inositol total choline, tNA, lactate and Cr ratios in frontal deep white matter and in the thalamus were similar in INPH patients and HI.

CONCLUSION

Reduced thalamic NAA and tNA in INPH patients suggest a compromised metabolic neuronal function in these regions. Thus, the thalamus might have an important role in the pathogenesis of INPH.

5% lidocaine medicated plaster versus pregabalin in post-herpetic neuralgia and diabetic polyneuropathy: an open-label, non-inferiority two-stage RCT study

OBJECTIVE

To compare efficacy and safety of 5% lidocaine medicated plaster with pregabalin in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

STUDY DESIGN AND METHODS

This was a two-stage adaptive, randomized, open-label, multicentre, non-inferiority study. Data are reported from the initial 4-week comparative phase, in which adults with PHN or painful DPN received either topical 5% lidocaine medicated plaster applied to the most painful skin area or twice-daily pregabalin capsules titrated to effect according to the Summary of Product Characteristics. The primary endpoint was response rate at 4 weeks, defined as reduction averaged over the last three days from baseline of > or = 2 points or an absolute value of < or = 4 points on the 11-point Numerical Rating Scale (NRS-3). Secondary endpoints included 30% and 50% reductions in NRS-3 scores; change in allodynia severity rating; quality of life (QoL) parameters EQ-5D, CGIC, and PGIC; patient satisfaction with treatment; and evaluation of safety (laboratory parameters, vital signs, physical examinations, adverse events [AEs], drug-related AEs [DRAEs], and withdrawal due to AEs).

RESULTS

Ninety-six patients with PHN and 204 with painful DPN were analysed (full analysis set, FAS). Overall, 66.4% of patients treated with the 5% lidocaine medicated plaster and 61.5% receiving pregabalin were considered responders (corresponding numbers for the per protocol set, PPS: 65.3% vs. 62.0%). In PHN more patients responded to 5% lidocaine medicated plaster treatment than to pregabalin (PPS: 62.2% vs. 46.5%), while response was comparable for patients with painful DPN (PPS: 66.7% vs 69.1%). 30% and 50% reductions in NRS-3 scores were greater with 5% lidocaine medicated plaster than with pregabalin. Both treatments reduced allodynia severity. 5% lidocaine medicated plaster showed greater improvements in QoL based on EQ-5D in both PHN and DPN. PGIC and CGIC scores indicated greater improvement for 5% lidocaine medicated plaster treated patients with PHN. Improvements were comparable between treatments in painful DPN. Fewer patients administering 5% lidocaine medicated plaster experienced AEs (safety set, SAF: 18.7% vs. 46.4%), DRAEs (5.8% vs. 41.2%) and related discontinuations compared to patients taking pregabalin.

CONCLUSION

5% lidocaine medicated plaster showed better efficacy compared with pregabalin in patients with PHN. Within DPN, efficacy was comparable for both treatments. 5% lidocaine medicated plaster showed a favourable efficacy/safety profile with greater improvements in patient satisfaction and QoL compared with pregabalin for both indications, supporting its first line position in the treatment of localized neuropathic pain.

Efficacy and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin in post-herpetic neuralgia and diabetic polyneuropathy

OBJECTIVE

Neuropathic pain is often difficult to treat due to a complex pathophysiology. This study evaluated the efficacy, tolerability and safety of combination therapy with 5% lidocaine medicated plaster and pregabalin for neuropathic pain in patients with post-herpetic neuralgia (PHN) or painful diabetic polyneuropathy (DPN).

METHODS

Patients completing 4-week monotherapy with 5% lidocaine medicated plaster or pregabalin were enrolled in an 8-week combination phase. Patients with adequate response to monotherapy (recalled average pain intensity of 4 or less on 11-point numeric rating scale in the previous 3 days [NRS-3 score]) continued their previous therapy, whereas those with insufficient response received combination therapy. Efficacy endpoints included change in NRS-3 from combination phase baseline, Patient and Clinical Global Impression of Change (PGIC/CGIC), and patient's satisfaction with treatment. Safety evaluation included adverse events (AEs), drug-related AEs (DRAEs), and withdrawal due to AEs.

CLINICAL TRIAL REGISTRATION

EudraCT No. 2006-003132-29.

RESULTS

Of 229 patients in the per-protocol set (PPS: 68 PHN and 161 DPN), 71 received 5% lidocaine medicated plaster monotherapy, 57 had pregabalin added to 5% lidocaine medicated plaster, 57 pregabalin monotherapy and 44 received 5% lidocaine medicated plaster in addition to continued pregabalin treatment. There were no meaningful differences in demographic data between the treatment groups. Patients continuing on monotherapy demonstrated additional decreases in NRS-3 scores. Patients receiving combination therapy achieved clinically relevant reduction in NRS-3 values in addition to improvement achieved during the 4 weeks of monotherapy. Improvement was similar between the two combination therapy groups. Considerable improvements in patients' treatment satisfaction were reported. Incidences of AEs were in line with previous reports for the two treatments and combination therapy was generally well tolerated.

CONCLUSIONS

In patients with PHN and painful DPN failing to respond to monotherapy, combination therapy with 5% lidocaine medicated plaster and pregabalin provides additional clinically relevant pain relief and is safe and well-tolerated.

Efficacy and safety of 5% lidocaine (lignocaine) medicated plaster in comparison with pregabalin in patients with postherpetic neuralgia and diabetic polyneuropathy: interim analysis from an open-label, two-stage adaptive, randomized, controlled trial

BACKGROUND AND OBJECTIVE

Postherpetic neuralgia (PHN) and diabetic polyneuropathy (DPN) are two common causes of peripheral neuropathic pain. Typical localized symptoms can include burning sensations or intermittent shooting or stabbing pains with or without allodynia. Evidence-based treatment guidelines recommend the 5% lidocaine (lignocaine) medicated plaster or pregabalin as first-line therapy for relief of peripheral neuropathic pain. This study aimed to compare 5% lidocaine medicated plaster treatment with pregabalin in patients with PHN and patients with DPN.

METHODS

The study was a two-stage, adaptive, randomized, controlled, open-label, multicentre trial that incorporated a drug wash-out phase of up to 2 weeks prior to the start of the comparative phase. At the end of the enrollment phase, patients who fulfilled the eligibility criteria were randomized to either 5% lidocaine medicated plaster or pregabalin treatment and entered the 4-week comparative phase. The interim analysis represents the first stage of the two-stage adaptive trial design and was planned to include data from the comparative phase for the first 150 randomized patients of the 300 total planned for the trial. Patients aged > or = 18 years with PHN or DPN were recruited from 53 investigational centres in 14 European countries. For this interim analysis, 55 patients with PHN and 91 with DPN (full-analysis set [FAS]), randomly assigned to the treatment groups, were available for analysis. Topical 5% lidocaine medicated plaster treatment was administered by patients to the area of most painful skin. A maximum of three or four plasters were applied for up to 12 hours within each 24-hour period in patients with PHN or DPN, respectively. Pregabalin capsules were administered orally, twice daily. The dose was titrated to effect: all patients received 150 mg/day in the first week and 300 mg/day in the second week of treatment. After 1 week at 300 mg/day, the dose of pregabalin was further increased to 600 mg/day in patients with high pain intensity scores. The pre-planned primary study endpoint was the rate of treatment responders, defined as completing patients experiencing a reduction from baseline of > or = 2 points or an absolute value of < or = 4 points on the 11-item numerical rating scale of recalled average pain intensity over the last 3 days (NRS-3), after 4 weeks of treatment. Secondary endpoints included > or = 30% and > or = 50% reductions in NRS-3 scores, changes in neuropathic pain symptom inventory (NPSI) scores and allodynia severity ratings. Overall, 65.3% of patients treated with the 5% lidocaine medicated plaster and 62.0% receiving pregabalin responded to treatment with respect to the primary endpoint. A higher proportion of PHN patients responded to plaster treatment compared with pregabalin (63.0% vs 37.5%), whereas in the larger DPN group treatments were comparable. Both treatments improved NPSI scores and reduced allodynia severity. Patients administering lidocaine plaster experienced fewer drug-related adverse events (3.9% vs 39.2%) and there were substantially fewer discontinuations due to drug-related adverse events (1.3% vs 20.3%).

CONCLUSION

After 4 weeks, 5% lidocaine medicated plaster treatment was associated with similar levels of analgesia in patients with PHN or DPN but substantially fewer frequent adverse events than pregabalin.

Comparison of clinical findings and psychosocial factors in patients with atypical odontalgia and temporomandibular disorders

AIMS

To systematically compare clinical findings and psychosocial factors between patients suffering from atypical odontalgia (AO) and an age- and gender-matched group of patients with temporomandibular disorders (TMD).

METHODS

Forty-six AO patients (7 men and 39 women; mean age, 56 years) were compared with 41 TMD patients (8 men and 33 women; mean age, 58 years).

RESULTS

Mean pain intensity at the time of inclusion in the study was similar between the groups (TMD: 5.3 +/- 0.4, AO: 5.0 +/- 0.3), but pain duration was longer in AO patients (AO: 7.7 +/- 1.1 years, TMD: 4.5 +/- 0.1 years). Eighty-three percent of the AO patients and 15% of TMD patients reported pain onset in relation to dental/surgical procedures. Episodic tension-type headache (TTH) occurred equally in both groups (TMD: 46%, AO: 46%), but TMD patients more frequently experienced chronic TTH (TMD: 35%, AO: 18%), myofascial TMD (TMD: 93%, AO: 50%), and temporomandibular joint disorders (TMD: 66%, AO: 2%). Overall, TMD patients had lower pressure pain thresholds and poorer jaw function than AO patients. Mean depression and somatization scores were moderate to severe in both groups, and widespread pain was most common in TMD patients.

CONCLUSION

AO and TMD share some characteristics but differ significantly in report of dental trauma, jaw function, pain duration, and pain site.

Clinical findings and psychosocial factors in patients with atypical odontalgia: a case-control study

AIM

To provide a systematic description of clinical findings and psychosocial factors in patients suffering from atypical odontalgia (AO).

METHODS

Forty-six consecutive AO patients (7 men and 39 women; mean age, 56 years; range, 31 to 81 years) were compared with 35 control subjects (11 men and 24 women; mean age, 59 years; range, 31 to 79 years).

RESULTS

The pain of the AO patients was characterized by persistent, moderate pain intensity (mean, 5.6 +/- 1.9) with long pain duration (mean, 7.7 +/- 7.8 years). Eighty-three percent reported that onset of pain occurred in conjunction with dental treatment. No significant difference was found between the groups in number of remaining teeth or number of root fillings. Temporomandibular disorder (TMD) pain (P < .001), tension-type headache (P < .002), and widespread pain (P < .001) were significantly more common among AO patients than controls. Significantly higher scores for somatization (P < .01) and depression (P < .01) and limitations in jaw function (P < .001) were found for the AO group compared with the control group. Significant differences between groups were found in 4 general health domains: role-physical (P < .001), bodily pain (P < .001), vitality (P < .004), and social functioning (P < .001).

CONCLUSION

A majority of the AO patients reported persistent, moderately intense intraoral pain that in most cases had an onset in conjunction with dental treatment. AO patients had more comorbid pain conditions and higher scores for depression and somatization. Significant limitation in jaw function and significantly lower scores on quality of life measures were found for AO patients compared with controls.

Effect of local anesthesia on atypical odontalgia – A randomized controlled trial

The aim of the study was to evaluate the analgesic effect of lidocaine in a double-blind, controlled multi-center study on patients with atypical odontalgia (AO)--a possible orofacial neuropathic pain condition. Thirty-five consecutive AO patients (range 31-81 years) with a mean pain duration of 7.2 years (range 1-30 years) were recruited from four different orofacial pain clinics in Sweden. In a randomized cross-over design, 1.5 ml local anesthesia (20mg/ml lidocaine and 12.5 microg/ml adrenaline) or 1.5 ml saline (9 mg/ml NaCl solution) (placebo) was injected to block the painful area. The VAS pain scores showed an overall effect of time (ANOVA: P<0.001) and treatment (ANOVA: P=0.018) with a significant interaction between the factors (ANOVA: P<0.001). Overall, VAS pain relief was significantly greater at 15-120 min following the lidocaine injections compared to the placebo injections (Tukey: P<0.05). All patients demonstrated significant disturbances in somatosensory function on the painful side compared to the non-painful side as revealed by quantitative sensory tests, however, only one significant inverse correlation was found between percentage pain relief and the magnitude of brush-evoked allodynia (Spearman: P<0.01). In conclusion, AO patients experienced significant, but not complete, pain relief from administration of local anesthetics compared with placebo. The findings indicate that the spontaneous pain in AO patients only to some extent is dependent on peripheral afferent inputs and that sensitization of higher order neurons may be involved in the pathophysiology of AO.

Blink reflexes in patients with atypical odontalgia

AIMS

To use the human blink reflex (BR) to explore possible neuropathic pain mechanisms in patients with atypical odontalgia (AO).

METHODS

In 13 AO patients, the BR was elicited using a concentric electrode and recorded bilaterally with surface electromyographic (EMG) electrodes on both orbicularis oculi muscles. Electrical stimuli were applied to the skin above branches of the V1, V2, and V3 nerves and to the V branch contralateral to the painful branch. Sensory and pain thresholds were determined. The BR examination of the painful V branch was repeated during a capsaicin pain-provocation test. The data were analyzed with nonparametric statistics.

RESULTS

The BR responses (R2 and R3) evoked by stimulation of V3 were significantly smaller than the BR responses evoked by stimulation of V1 and V2 (P < .004). There were no differences in BR (R2 or R3) between the painful and nonpainful sides (P > .569), and the BR (R2 and R3) was not significantly modulated by experimental pain (P > .080). The sensory thresholds were significantly lower on the painful side compared to the nonpainful side (P = .014). The pain thresholds were not different between sides (P > .910).

CONCLUSION

No major differences between the V nociceptive pathways on the right and left sides were found in a relatively small group of AO patients. Future studies that compare BRs in AO patients and healthy volunteers are needed to provide further knowledge on the pain mechanisms in AO.

Pharmacologic interventions in the treatment of temporomandibular disorders, atypical facial pain, and burning mouth syndrome. A qualitative systematic review

AIMS

To carry out a systematic review of the literature in order to assess the pain-relieving effect and safety of pharmacologic interventions in the treatment of chronic temporomandibular disorders (TMD), including rheumatoid arthritis (RA), as well as atypical facial pain (AFP), and burning mouth syndrome (BMS).

METHODS

Study selection was based on randomized clinical trials (RCTs). Inclusion criteria included studies on adult patients (> or = 18 years) with TMD, RA of the temporomandibular joint (TMJ), AFP, or BMS and a pain duration of > 3 months. Data sources included Medline, Cochrane Library, Embase, and Psych Litt.

RESULTS

Eleven studies with a total of 368 patients met the inclusion criteria. Four trials were on TMD patients, 2 on AFP, 1 on BMS, 1 on RA of the TMJ, and 3 on mixed groups of patients with TMD and AFP. Of the latter, amitriptyline was effective in 1 study and benzodiazepine in 2 studies; the effect in 1 of the benzodiazepine studies was improved when ibuprofen was also given. One study showed that intra-articular injection with glucocorticoid relieved the pain of RA of the TMJ. In 1 study, a combination of paracetamol, codeine, and doxylamine was effective in reducing TMD pain. No effective pharmacologic treatment was found for BMS. Only minor adverse effects were reported in the studies.

CONCLUSION

The common use of analgesics in TMD, AFP, and BMS is not supported by scientific evidence. More large RCTs are needed to determine which pharmacologic interventions are effective in TMD, AFP, and BMS.

Transcutaneous electrical nerve stimulation (TENS) for chronic pain

BACKGROUND

Transcutaneous electrical nerve stimulation (TENS) is used in a variety of different clinical settings to treat a range of different acute and chronic pain conditions and has become popular with both patients and health professionals.

OBJECTIVES

To evaluate the effectiveness of TENS in chronic pain.

SEARCH STRATEGY

The Cochrane Library, Embase, Medline, CINAHL and The Oxford Pain Database were searched. Reference lists from retrieved reports and reviews were examined. Date of the most recent search: March 1999.

SELECTION CRITERIA

RCTs were eligible if they included the following treatment comparisons: active TENS versus sham TENS controls active TENS versus no treatment controls active TENS versus active TENS controls (for instance High Frequency TENS vs Low Frequency TENS) Studies of patients suffering chronic pain for three months or more which included subjective outcome measures for pain intensity, or pain relief were eligible for evaluation in this review. No restrictions were made to language or sample size. Data from abstracts, letters, or unpublished studies, and studies of TENS in angina, headache and migraine, and dysmenorrhoea were not included.

DATA COLLECTION AND ANALYSIS

Data were extracted and summarised on the following items: patients and details of pain condition, study treatments, study duration, design, methods, subjective pain outcome measures, methodological quality, results for pain outcome measures and adverse effects, and the conclusions made by the authors of the original studies. Extracted data and methodological quality of each report was confirmed by at least three of the reviewers.

MAIN RESULTS

Of 107 reports identified from the searches, 88 were excluded as they did not fulfil the pre-defined entry criteria. Nineteen RCTs (from 18 reports) were evaluated. The included trials varied in terms of design, analgesic outcomes, chronic pain conditions, TENS treatments and overall methodological quality. Studies included single and multiple dose treatment comparisons of TENS. The studies were small. The reporting of the methods used and results for the analgesic outcomes were generally poor. TENS treatments and controls were often poorly defined. Few studies evaluated the long-term analgesic effectiveness of TENS and single dose evaluations of TENS are unhelpful in making clinical decisions of the long-term effectiveness of TENS in the management of chronic pain. Meta-analysis was not possible. Overall in 10 of 15 inactive control studies there was a positive analgesic outcome in favour of the active TENS treatments. For the multiple dose treatment comparison studies only three of seven were considered to be in favour of the active TENS treatments. For the active controlled studies, seven studies made direct comparisons between HFTENS and LFTENS. Five of seven studies could find no difference in terms of analgesic efficacy between HFTENS and LFTENS at any time point.

REVIEWER'S CONCLUSIONS

The results of this review are inconclusive; the published trials do not provide information on the stimulation parameters which are most likely to provide optimum pain relief, nor do they answer questions about long-term effectiveness. Large multi-centre randomised controlled trials of TENS in chronic pain are urgently needed.

Central poststroke pain: correlation of MRI with clinical pain characteristics and sensory abnormalities

OBJECTIVE

To correlate MRI and sensory changes in patients with spontaneous lesions in the cerebral "pain pathway."

METHODS

The authors used MRI and quantitative somatosensory testing in 73 patients with central poststroke pain (CPSP) and in 13 patients with pain-free stroke with sensory deficit.

RESULTS

Lesions in any part of the discriminatory somatosensory pathway may or may not produce CPSP. Most CPSP patients have multiple lesions, many probably unrelated to pain. Ventroposterior thalamic nuclear lesions are more likely to produce half-body pain than lesions elsewhere (including the brainstem). In supratentorial lesions, the greatest pain is more likely to be in an extremity, and in infratentorial lesions, the greatest pain is likely to be in the face. Supratentorial CPSP patients have a deficit of sharpness and cold (peripherally mediated by A delta fibers) than pain-free stroke patients, whereas patients with infratentorial CPSP additionally have a deficit of C-fiber-mediated warmth and hot pain. Burning pain is more common than nonburning pain in younger patients. Warmth and cold, but not hot pain, exhibiting central convergence (spatial summation) are more affected in CPSP patients with burning than nonburning pain. Allodynic CPSP patients had a significantly greater deficit for warmth than patients without allodynia.

CONCLUSIONS

Different stroke sites produce different patterns of sensory deficit. The progression from painless sensory deficit to CPSP is not purely quantitative.

Laser-evoked cerebral potentials and sensory function in patients with central pain

Central pain syndromes (CPS) could be caused by disinhibition of spinothalamic excitability or by other central nervous system (CNS) changes caused by reduced spinothalamic function. To examine these possibilities, we studied 11 patients (ages 51-82 years) with unilateral central pain and with reproducible cerebral evoked vertex potentials in response to cutaneous stimulation of the normal side with pulses from an infra-red CO2 laser. All patients had normal tactile and kinesthetic sensation; one had slightly decreased vibratory sense bilaterally. All showed, from the unaffected (asymptomatic) side, laser evoked potentials (LEPs) with negative (N) components ranging from 208 to 280 msec peak latency (av: 240 +/- 6 SE msec) and peak amplitudes of 1-7 microV (av: 2.9 +/- 0.5 SE microV), followed, in all but 1 patient, by positive (P) potentials ranging from 288 to 370 msec peak latency (av: 319 +/- 7.7 SE msec) with peak amplitudes of 1-7 microV (2.8 +/- 0.5 SE microV). Laser stimulation of the affected (symptomatic) side in 5 patients evoked LEPs with N-P interpeak amplitudes that were within 20% of those evoked from the normal side. All but one of these patients had thresholds for warm, heat pain, and deep pain that were normal in comparison with the unaffected side. The excepted patient had the largest N-P interpeak amplitude asymmetry (18.5%) of this group. Ratings of laser pulse intensity were either symmetrical (n = 2) or increased on the affected side (n = 3) in these patients. In contrast, laser stimulation of the affected side failed to evoke either N or P potentials in 6 patients, all of whom had lateralized increased thresholds for warm, heat pain, or deep pain, or reduced ratings of laser pulse sensation. Although 1 patient had increased ratings of laser pulse sensation, the amplitude of the LEP was always reduced on the side of increased pain or heat threshold in these CPS patients (Fisher exact test: P = 0.015). These results reflect primarily a deficit in spinothalamic tract function and do not suggest excessive CNS responses to synchronous activation of cutaneous heat nociceptors in patients with CPS.

Central post-stroke pain--somatosensory evoked potentials in relation to location of the lesion and sensory signs

Somatosensory evoked potentials (SEPs) were studied in 27 patients with central post-stroke pain and in 19 controls. A scoring system for SEP was used, in which increasing abnormalities rendered increasing scores. SEPs evoked by electrical stimulation of the median and tibial nerves were compared to perception thresholds for touch, vibration, innocuous and noxious temperature. All patients had reduced temperature sensibility, while the threshold for touch and vibration was abnormal in only 52% and 41%, respectively. Decreased touch and vibration sensibility had a high correlation with high SEP scores, while no correlation was found between reduced temperature sensibility and SEP. The patients with thalamic lesions had the most severely affected SEPs, the ones with lower brain-stem lesions were the least affected. The results support the notion that the SEP is dependent on the lemniscal pathways and that lesions of the spinothalamic pathways are crucial for the development of CPS.

Central post-stroke pain--the effect of high and low frequency TENS

The effect of high (conventional) and low frequency (acupuncture-like) transcutaneous electrical nerve stimulation (Hi-, Lo-TENS) was tested in 15 patients with central post-stroke pain. During the initial 16 day trial of stimulation ipsilateral and contralateral to the pain, 4 patients obtained pain relief. Three of them benefitted from ipsilateral Hi- and Lo-TENS. Two patients also obtained pain relief with contralateral stimulation. Three patients continued to use TENS ipsilaterally with good effect at follow-up 23-30 months after the initial trial. In one-third of the patients, TENS temporarily increased the pain.

Central post-stroke pain--a study of the mechanisms through analyses of the sensory abnormalities

The somatosensory abnormalities in 20 men and 7 women (mean age 67 years, range 53-81) with central post-stroke pain (CPSP) have been analysed in detail with traditional neurological tests and quantitative methods. The cerebrovascular lesions were located in the lower brain-stem in 8 patients, involved the thalamus in 9 and in 6 were suprathalamic. In 4 patients the location of the CVL could not be determined. All patients had abnormal temperature and pain sensibility, with a severe deficit in most cases. All except 2 had raised thresholds to thermal pain and all except 1 had abnormal sensibility to pin-prick. Eighty-eight percent exhibited hyperpathia with combined loss and suprathreshold exaggeration of somatic sensibility. In 85% somatic stimuli evoked dysaesthesia and about half of these patients also experienced spontaneous dysaesthesia. Paraesthesias were reported by 41%, radiation of stimuli by 50%, after-sensations by 45% and allodynia by 23%. Vibration sensibility was abnormal in 41%; raised thresholds to the perception of touch were found in 52%, to 2-PD in 35%, to dermolexia in 45% and to joint movements in 37%. The results indicate that all patients with CPSP have lesions that affect the major pathways for temperature and pain sensibility, i.e., the spino-thalamo-cortical pathways. Furthermore it appears that neither the level of the lesion along the neuraxis nor concomitant injury to the medial lemniscal pathways is crucial for the development of CPSP. The results confirm the notion that CPSP is a deafferentation syndrome, but they also provide evidence against the hypothesis that CPSP is a release phenomenon caused by a lesion that removes inhibitory influences of the lemniscal pathways on neurones that evoke pain.

Central post-stroke pain--a controlled trial of amitriptyline and carbamazepine

A double-blind, 3-phase, cross-over, placebo-controlled trial of the pain-relieving effect of amitriptyline and carbamazepine was carried out in 15 patients with central post-stroke pain (CPSP) but without signs of depression. Treatment was given, in randomized order, for periods of 4 weeks, separated by 1 week wash-out. The final doses were 75 and 800 mg/day, respectively, for amitriptyline and carbamazepine. The treatment effects were assessed by daily ratings of pain intensity on a 10-step verbal scale and at the end of each treatment period by a global rating of the analgesic effect on a 5-step verbal scale. For the assessment of depression the Comprehensive Psychopathological Rating Scale (CPRS) was used. Amitriptyline produced a statistically significant reduction of pain when compared to placebo. According to the global rating, 10 of the 15 patients were responders to this drug. The effect could already be noticed during the second treatment week and it appeared to be correlated to the plasma concentration, since the median total ami- and nortriptyline concentrations were 497 and 247 nmol/l, respectively, for responders and non-responders. The early onset, together with the fact that the patients were not depressed, nor did they obtain reduced scores on ratings of depressive symptoms and signs, provides strong support for the conclusion that the pain relief was not caused by an antidepressive effect. Five of the 14 patients treated with carbamazepine reported some pain relief, but the effect did not reach statistical significance when compared to placebo. No correlation was found between effect and plasma concentration. In general, the patients tolerated the planned final dose of amitriptyline well. No final dose reduction was necessary. Carbamazepine caused more side effects and the final dose had to be reduced in 4 patients. However, only 1 patient had to be taken off medication, on day 25, due to drug interaction.

Central post-stroke pain--neurological symptoms and pain characteristics

The intention of the present study was to characterize patients with central post-stroke pain (CPSP) with regard to type and location of the cerebrovascular lesion (CVL), the characteristics of the pain and the neurological symptoms and signs in addition to the pain. Twenty men and 7 women with a mean age of 67 years and a mean pain duration of 44 months were examined 9-188 (mean 53) months after their stroke. The clinical symptoms and signs and the CT scans indicated that the CVL were located in the lower brain-stem in 8 patients, involved the thalamus in 9 patients and were located lateral and superior to the thalamus in 6 patients. In the remaining 4 patients the location of the CVL could not be determined with certainty. The 3 identified hematomata were all located in the thalamus. The onset of the pain was immediate in 4 patients, within the first post-stroke months in 10 patients and delayed by 1-34 months in the rest. The pain was on the left side in 18 patients. Twenty patients had hemipain. Most patients experienced more than one type of pain. The most common qualities were burning, aching, pricking and lacerating, with some differences in the frequencies according to the location of the CVL. Burning pain was most common, except among the patients with thalamic CVL, in whom lacerating pain was more common. Aching and pricking pain were also frequent. All patients considered the pain to be a great burden and most rated the pain intensity as high on a visual analogue scale. The intensity was increased by external stimuli, the most common being joint movements, cold and light touch. Five patients reported aggravation by emotional stimuli. Besides pain, the only neurological symptom common to all patients was decreased temperature sensibility, as shown by quantitative methods. It is possible that pain sensibility was also abnormal in all. Hypersensitivities to cutaneous stimuli, including evoked dysesthesias were found in 88% of the patients, while the detection thresholds for touch and vibration were abnormal in only 52% and 41%, respectively. Similarly, low figures were found for paresis and ataxia, which were present in 48% and 62%, respectively. It is concluded that only a minority of patients with central pain after stroke have thalamic lesions.(ABSTRACT TRUNCATED AT 400 WORDS)

Demonstration of serum IgG antibodies against myelin during the course of relapsing experimental allergic encephalomyelitis in guinea pigs

Chronic relapsing allergic encephalomyelitis (r-EAE) was induced in a local strain of guinea pigs. By the use of isoelectric focusing (IF) followed by antigen immunofixation and autoradiography, antibodies directed against central nervous system (CNS) myelin were detected in 21 of 23 sera sampled during the course of r-EAE. Previous absorption of the sera with CNS myelin reduced or abolished antibody activity on autoradiograms. One r-EAE guinea pig developed definite oligoclonal IgG bands in serum while in 7 r-EAE animals faint oligoclonal IgG bands were present. The mobility of oligoclonal IgG bands differed from the mobility of antimyelin antibody bands on autoradiograms. The significance of these findings has not been definitely elucidated but the antimyelin antibodies may possibly be involved in the pathogenesis of the disease while oligoclonal IgG bands may represent an epiphenomenon not pathogenetically related to r-EAE.