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

Antidepressants for the treatment of chronic pain

Chronic pain represents one of the most important public health problems and, in addition to classical analgesics, antidepressants are an essential part of the therapeutic strategy. This article reviews available evidence on the efficacy and safety of antidepressants in major chronic pain conditions; namely, neuropathic pain, headaches, low back pain, fibromyalgia, irritable bowel syndrome (IBS) and cancer pain. Studies, reviews and meta-analyses published from 1991 to March 2008 were retrieved through MEDLINE, PsycINFO and the Cochrane database using numerous key words for pain and antidepressants. In summary, evidence supports the use of tricyclic antidepressants in neuropathic pain, headaches, low back pain, fibromyalgia and IBS. The efficacy of the newer serotonin and norepinephrine reuptake inhibitors is less supported by evidence, but can be recommended in neuropathic pain, migraines and fibromyalgia. To date, evidence does not support an analgesic effect of serotonin reuptake inhibitors, but beneficial effects on well-being were reported in several chronic pain conditions. These results are discussed in the light of current insights in the neurobiology of pain, the reciprocal relationship between pain and depression, and future developments in this field of research.

Pregabalin in the management of central neuropathic pain

Central neuropathic pain is a painful condition, often severe, that occurs in a person who is already affected by an injury or disease of the brain or spinal cord. This dual insult is especially threatening to the quality of life of a person and their ability to perform even the most basic of tasks. Despite this high level of suffering there are relatively few trials investigating the management of central neuropathic pain. However, two randomised placebo-controlled studies have recently emerged demonstrating efficacy of pregabalin in reducing central neuropathic pain due to spinal cord injury and central poststroke pain. Pregabalin, an anticonvulsant, has been shown to be efficacious in the management of peripheral neuropathic pain of various causes and now may have a role to play in central neuropathic pain.

Clinical use of pregabalin in the management of central neuropathic pain

Central neuropathic pain (central pain) is treated with antidepressants, various anticonvulsants, opioids, and cannabinoids, but in many cases treatment is insufficient and associated with a range of side-effects. This review addresses a new treatment for neuropathic pain, the anticonvulsant pregabalin. We review the pharmacology, mode of action, pharmacokinetics, and safety of pregabalin as well as two randomized efficacy studies in central pain and a brief overview of efficacy in peripheral neuropathic pain. Pregabalin appears to have efficacy in treating central pain comparable to that in peripheral neuropathic pain as well as efficacy of other recommended drugs for central pain. Pregabalin also improves disturbed sleep and anxiety. Pregabalin is well tolerated; the most common side-effects are somnolence, dizziness, ataxia, and weight gain. Pregabalin is suitable for patients on multiple drugs although there may be additive CNS-related side-effects. Thus, pregabalin has a primary role in central pain patients.

Antidepressants for neuropathic pain

BACKGROUND

This is an updated version of the original Cochrane review published in Issue 3, 2005 of The Cochrane Library. For many years antidepressant drugs have been used to manage neuropathic pain, and are often the first choice treatment. It is not clear, however, which antidepressant is more effective, what role the newer antidepressants can play in treating neuropathic pain, and what adverse effects are experienced by patients.

OBJECTIVES

To determine the analgesic effectiveness and safety of antidepressant drugs in neuropathic pain.

SEARCH STRATEGY

Randomised controlled trials (RCTs) of antidepressants in neuropathic pain were identified in MEDLINE (1966 to Oct 2005); EMBASE (1980 to Oct 2005); the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, Issue 3, 2005; and the Cochrane Pain, Palliative and Supportive Care Trials Register (May 2002). Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators.

SELECTION CRITERIA

RCTs reporting the analgesic effects of antidepressant drugs in adult patients, with subjective assessment of pain of neuropathic origin. Studies that included patients with chronic headache and migraine were excluded.

DATA COLLECTION AND ANALYSIS

Two review authors agreed the included studies, extracted data, and assessed methodological quality independently. Sixty one trials of 20 antidepressants were considered eligible (3293 participants) for inclusion. Relative Risk (RR) and Number-Needed-to-Treat (NNTs) were calculated from dichotomous data for effectiveness and adverse effects. This update includes 11 additional studies (778 participants).

MAIN RESULTS

Sixty one RCTs were included in total. Tricyclic antidepressants (TCAs) are effective and have an NNT of 3.6 (95% CI 3 to 4.5) RR 2.1 (95% CI 1.8 to 2.5) for the achievement of at least moderate pain relief. There is limited evidence for the effectiveness of the newer SSRIs but no studies of SNRIs were found. Venlafaxine (three studies) has an NNT of 3.1 (95% CI 2.2 to 5.1) RR 2.2 (95% CI 1.5 to 3.1). There were insufficient data to assess effectiveness for other antidepressants such as St Johns Wort and L-tryptophan. For diabetic neuropathy the NNT for effectiveness was 1.3 (95% CI 1.2 to 1.5) RR 12.4 (95% CI 5.2 to 29.2) (five studies); for postherpetic neuralgia 2.7 (95% CI 2 to 4.1), RR 2.2 (95% CI 1.6 to 3.1) (four studies). There was evidence that TCAs are not effective in HIV-related neuropathies. The number needed to harm (NNH) for major adverse effects defined as an event leading to withdrawal from a study was 28 (95% CI 17.6 to 68.9) for amitriptyline and 16.2 (95% CI 8 to 436) for venlafaxine. The NNH for minor adverse effects was 6 (95% CI 4.2 to 10.7) for amitriptyline and 9.6 (95% CI 3.5 to 13) for venlafaxine.

AUTHORS' CONCLUSIONS

This update has provided additional confirmation on the effectiveness of antidepressants for neuropathic pain and has provided new information on another antidepressant - venlafaxine. There is still limited evidence for the role of SSRIs. Whether antidepressants prevent the development of neuropathic pain (pre-emptive use) is still unclear. Both TCAs and venlafaxine have NNTs of approximately three. This means that for approximately every three patients with neuropathic pain who are treated with either of these antidepressants, one will get at least moderate pain relief. There is evidence to suggest that other antidepressants may be effective but numbers of participants are insufficient to calculate robust NNTs. SSRIs are generally better tolerated by patients and more high quality studies are required.

Voltage-gated Na+channels in neuropathic pain

Neuropathic pain occurs as a result of some form of injury to the nervous system. Although the basis of the disease remains to be fully elucidated, numerous studies have suggested a major role for ion channels in the pathogenesis of neuropathic pain. As Na+ channels play a fundamental role in not only the generation but also in the conduction of an action potential, they have received considerable attention in the aetiology of pain sensation and have become important pharmacological targets. In this review, the authors discuss the importance of specific Na+ channel isoforms in the pathophysiology of neuropathic pain and the present use of Na+ channel antagonists in the treatment of neuropathic pain.

Anti-convulsants and anti-depressants

Damage to a nerve should only lead to sensory loss. While this is common, the incidence of spontaneous pain, allodynia and hyperalgesia indicate marked changes in the nervous system that are possible compensations for the loss of normal function that arises from the sensory loss. Neuropathic pain arises from changes in the damaged nerve which then alter function in the spinal cord and the brain and lead to plasticity in areas adjacent to those directly influenced by the neuropathy. The peripheral changes drive central compensations so that the mechanisms involved are multiple and located at a number of sites. Nerve damage increases the excitability of both the damaged and undamaged nerve fibres, neuromas and the cell bodies in the dorsal root ganglion. These peripheral changes are substrates for the ongoing pain and the efficacy of excitability blockers such as carbamazepine, lamotrigine and mexiletine, all anti-convulsants. A better understanding of ion channels at the sites of injury has shown important roles of particular sodium, potassium and calcium channels in the genesis of neuropathic pain. Within the spinal cord, increases in the activity of calcium channels and the receptors for glutamate, especially the N-methyl-D-aspartate (NMDA) receptor, trigger wind-up and central hyperexcitability. Increases in transmitter release, neuronal excitability and receptive field size result from the damage to the peripheral nerves. Ketamine and gabapentin/pregabalin, again with anti-convulsant activity, may interact with these mechanisms. Ketamine acts on central spinal mechanisms of excitability whereas gabapentin acts on a subunit of calcium channels that is responsible for the release of pain transmitters into the spinal cord. In addition to these spinal mechanisms of hyperexcitability, spinal cells participate in a spinal-supraspinal loop that involves parts of the brain involved in affective responses to pain but also engages descending excitatory and inhibitory systems that use the monoamines. These pathways become more active after nerve injury and are the site of action of anti-depressants. This chapter reviews the evidence and mechanisms of drugs, both anti-depressants and anti-convulsants, that are believed to be effective in pain control, with a major emphasis on the neuropathic state.

Use of antiepileptic drugs for nonepileptic conditions: psychiatric disorders and chronic pain

Antiepileptic drugs (AEDs) are commonly utilized for nonepileptic conditions, including various psychiatric disorders and pain syndromes. Evidence for their benefit in these nonepileptic conditions varies widely among different drugs, but there is, in general, a paucity of published multicenter randomized double-blind trials. Variable levels of evidence suggest that lamotrigine and the vagal nerve stimulator have antidepressant properties. Carbamazepine, valproate, lamotrigine, and oxcarbazepine appear to have mood stabilizing properties while gabapentin, pregabalin, and tiagabine have anxiolytic benefits. Barbiturates, topiramate, and possibly phenytoin may precipitate or exacerbate depression. Underlying depression and anxiety symptoms may be exacerbated by levetiracetam, while psychotic symptoms have rarely been reported with topiramate, levetiracetam, and zonisamide. Pregabalin, gabapentin, carbamazepine, and oxcarbazepine have been used to treat neuropathic pain such as postherpetic neuralgia, and diabetic polyneuropathy. Topiramate and divalproex sodium have utility in the prophylaxis or acute treatment of migraine. Further rigorous studies are needed to clarify the utility of AEDs in nonepileptic conditions.

EFNS guidelines on pharmacological treatment of neuropathic pain

Neuropathic pain treatment remains unsatisfactory despite a substantial increase in the number of trials. This EFNS Task Force aimed at evaluating the existing evidence about the pharmacological treatment of neuropathic pain. Studies were identified using first the Cochrane Database then Medline. Trials were classified according to the aetiological condition. All class I and II controlled trials (according to EFNS classification of evidence) were assessed, but lower-class studies were considered in conditions that had no top level studies. Only treatments feasible in an outpatient setting were evaluated. Effects on pain symptoms/signs, quality of life and comorbidities were particularly searched for. Most of the randomized controlled trials included patients with postherpetic neuralgia (PHN) and painful polyneuropathies (PPN) mainly caused by diabetes. These trials provide level A evidence for the efficacy of tricyclic antidepressants, gabapentin, pregabalin and opioids, with a large number of class I trials, followed by topical lidocaine (in PHN) and the newer antidepressants venlafaxine and duloxetine (in PPN). A small number of controlled trials were performed in central pain, trigeminal neuralgia, other peripheral neuropathic pain states and multiple-aetiology neuropathic pains. The main peripheral pain conditions respond similarly well to tricyclic antidepressants, gabapentin, and pregabalin, but some conditions, such as HIV-associated polyneuropathy, are more refractory. There are too few studies on central pain, combination therapy, and head-to-head comparison. For future trials, we recommend to assess quality of life and pain symptoms or signs with standardized tools.

Antidepressant and anticonvulsant medication for chronic pain

Antidepressants and anticonvulsants have been shown to be efficacious in the treatment of neuropathic pain, chronic headache, and other chronic pain conditions. They may be useful in the treatment of disorders in which central nervous system hypersensitivity con-tributes to pain. They provide valuable alternatives or adjuncts to the use of opioid medications in the treatment of chronic pain. Antidepressants have several potential roles in the treatment of chronic pain in addition to their analgesic effects. Specifically, they effectively address the sleep disturbance, depression, and anxiety that are common in patients with chronic pain.

Pharmacologic Treatment of Central Post-Stroke Pain

OBJECTIVES

Almost 100 years after the first report of the thalamic syndrome, the scientific basis for the treatment of central post-stroke pain (CPSP) is remarkably small. Therefore, the authors aimed to provide evidence-based recommendations for the treatment of CPSP.

METHODS

The authors performed a systematic review of the literature on the pharmacologic treatment of CPSP. All studies and case series were included and evaluated according to their level of evidence. Only CPSP was considered, not other types of central pain.

RESULTS

Amitriptyline and lamotrigine are the only oral drugs proven to be effective in the treatment of CPSP in a placebo-controlled study. IV drugs such as lidocaine, propofol, and ketamine have shown efficacy for short-term control of CPSP, but their application and potential side effects make them unsuitable for long-term treatment. The novel antiepileptic drug gabapentin has been reported to control CPSP in a few patients.

CONCLUSIONS

Amitriptyline, lamotrigine, and gabapentin provide a more favorable efficacy and safety profile than the classic antiepileptic drugs carbamazepine and phenytoin, for which no placebo-controlled evidence of efficacy was found. Clinical trials are urgently needed to optimize pharmacologic treatment of CPSP.

Algorithm for neuropathic pain treatment: an evidence based proposal

New studies of the treatment of neuropathic pain have increased the need for an updated review of randomized, double-blind, placebo-controlled trials to support an evidence based algorithm to treat neuropathic pain conditions. Available studies were identified using a MEDLINE and EMBASE search. One hundred and five studies were included. Numbers needed to treat (NNT) and numbers needed to harm (NNH) were used to compare efficacy and safety of the treatments in different neuropathic pain syndromes. The quality of each trial was assessed. Tricyclic antidepressants and the anticonvulsants gabapentin and pregabalin were the most frequently studied drug classes. In peripheral neuropathic pain, the lowest NNT was for tricyclic antidepressants, followed by opioids and the anticonvulsants gabapentin and pregabalin. For central neuropathic pain there is limited data. NNT and NNH are currently the best way to assess relative efficacy and safety, but the need for dichotomous data, which may have to be estimated retrospectively for old trials, and the methodological complexity of pooling data from small cross-over and large parallel group trials, remain as limitations.

Antidepressants in the treatment of neuropathic pain

Neuropathic pain is due to lesion or dysfunction of the peripheral or central nervous system. Tricyclic antidepressants and anticonvulsants have long been the mainstay of treatment of this type of pain. Tricyclic antidepressants may relieve neuropathic pain by their unique ability to inhibit presynaptic reuptake of the biogenic amines serotonin and noradrenaline, but other mechanisms such as N-methyl-D-aspartate receptor and ion channel blockade probably also play a role in their pain-relieving effect. The effect of tricyclic antidepressants in neuropathic pain in man has been demonstrated in numerous randomised, controlled trials, and a few trials have shown that serotonin noradrenaline and selective serotonin reuptake inhibitor antidepressants also relieve neuropathic pain although with lower efficacy. Tricyclic antidepressants will relieve one in every 2-3 patients with peripheral neuropathic pain, serotonin noradrenaline reuptake inhibitors one in every 4-5 and selective serotonin reuptake inhibitors one in every 7 patients. Thus, based on efficacy measures such as numbers needed to treat, tricyclic antidepressants tend to work better than the anticonvulsant gabapentin and treatment options such as tramadol and oxycodone, whereas the serotonin noradrenaline reuptake inhibitor venlafaxine appears to be equally effective with these drugs and selective serotonin reuptake inhibitors apparently have lower efficacy. Head-to-head comparisons between antidepressants and the other analgesics are lacking. Contraindications towards the use of tricyclic antidepressants and low tolerability in general of this drug class--may among the antidepressants--favour the use of the serotonin noradrenaline reuptake inhibitors. A recent study on bupropion, which is a noradrenaline and dopamine uptake inhibitor, indicated a surprisingly high efficacy of this drug in peripheral neuropathic pain. In conclusion, antidepressants represent useful tools in neuropathic pain treatment and must still be considered as first line treatments of neuropathic pain. However, without head-to-head comparisons between antidepressants and other analgesics, it is not possible to provide real evidence-based treatment algorithms for neuropathic pain.

Anticonvulsant drugs for acute and chronic pain

BACKGROUND

Anticonvulsant drugs have been used in the management of pain since the 1960s. The clinical impression is that they are useful for chronic neuropathic pain, especially when the pain is lancinating or burning. Readers are referred to reviews of carbamazepine and gabapentin in the Cochrane Library which replace the information on those drugs in this review. Other drugs remain unchanged at present in this review

OBJECTIVES

To evaluate the analgesic effectiveness and adverse effects of anticonvulsant drugs for pain management in clinical practice . Migraine and headache studies are excluded in this revision.

SEARCH STRATEGY

Randomised trials of anticonvulsants in acute, chronic or cancer pain were identified by MEDLINE (1966-1999), EMBASE (1994-1999), SIGLE (1980-1999) and the Cochrane Controlled Trials Register (CENTRAL/CCTR) (Cochrane Library Issue 3, 1999). In addition, 41 medical journals were hand searched. Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators. Date of most recent search: September 1999.

SELECTION CRITERIA

Randomised trials reporting the analgesic effects of anticonvulsant drugs in patients, with subjective pain assessment as either the primary or a secondary outcome.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent reviewers, and trials were quality scored. Numbers-needed-to-treat (NNTs) were calculated from dichotomous data for effectiveness, adverse effects and drug-related study withdrawal, for individual studies and for pooled data.

MAIN RESULTS

Twenty-three trials of six anticonvulsants were considered eligible (1,074 patients). The only placebo-controlled study in acute pain found no analgesic effect of sodium valproate. Three placebo-controlled studies of carbamazepine in trigeminal neuralgia had a combined NNT (95% confidence interval (CI)) for effectiveness of 2.5 (CI 2.0-3.4). A single placebo-controlled trial of gabapentin in post-herpetic neuralgia had an NNT of 3.2 (CI 2.4-5.0). For diabetic neuropathy NNTs for effectiveness were as follows: (one RCT for each drug) carbamazepine 2.3 (CI 1.6-3.8), gabapentin 3.8 (CI 2.4-8.7) and phenytoin 2.1 (CI 1.5-3.6).Numbers-needed-to-harm (NNHs) were calculated where possible by combining studies for each drug entity irrespective of the condition treated. The results were, for minor harm, carbamazepine 3.7 (CI 2.4-7.8), gabapentin 2.5 (CI 2.0-3.2), phenytoin 3.2 (CI 2.1-6.3). NNHs for major harm were not statistically significant for any drug compared with placebo. Phenytoin had no effect in irritable bowel syndrome, and carbamazepine little effect in post-stroke pain. Clonazepam was effective in one study of temporomandibular joint dysfunction.

AUTHORS' CONCLUSIONS

Although anticonvulsants are used widely in chronic pain surprisingly few trials show analgesic effectiveness. Only one studied considered cancer pain. There is no evidence that anticonvulsants are effective for acute pain. In chronic pain syndromes other than trigeminal neuralgia, anticonvulsants should be withheld until other interventions have been tried. While gabapentin is increasingly being used for neuropathic pain the evidence would suggest that it is not superior to carbamazepine.

Antidepressants for neuropathic pain

BACKGROUND

For many years antidepressant drugs have been used to manage neuropathic pain, and are often the first choice treatment. It is not clear, however, which antidepressant is more effective, what role the newer antidepressants can play in treating neuropathic pain, and what adverse effects are experienced by patients.

OBJECTIVES

To determine the analgesic effectiveness and safety of antidepressant drugs in neuropathic pain. Migraine and headache studies were not considered.

SEARCH STRATEGY

Randomised trials of antidepressants in neuropathic pain were identified in MEDLINE (1966 to Dec 2003); EMBASE (1980 to Dec 2003); the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library 2004, Issue 1; and the Cochrane Pain, Palliative and Supportive Care Trials Register (May 2002). Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators.

SELECTION CRITERIA

Randomised trials reporting the analgesic effects of antidepressant drugs in adult patients, with subjective assessment of pain of neuropathic origin. Studies that included patients with chronic headache and migraine were excluded.

DATA COLLECTION AND ANALYSIS

Two reviewers agreed the included studies, extracted data, and assessed methodological quality independently. Fifty trials of 19 antidepressants were considered eligible (2515 patients) for inclusion. Relative Risk (RR) estimates and Number-Needed-to-Treat (NNTs) were calculated from dichotomous data for effectiveness and adverse effects.

MAIN RESULTS

Tricyclic antidepressants (TCAs) are effective treatments for the treatment of neuropathic pain. Amitriptyline has an NNT of 2 (95%CI 1.7 to 2.5) RR 4.1(95%CI 2.9-5.9) for the achievement of at least moderate pain relief. There is limited evidence for the effectiveness of the newer selective serotonin reuptake inhibitor antidepressant drugs (SSRIs). There were insufficient data for an assessment of evidence of effectiveness for other antidepressants such as St Johns Wort, venlafaxine and L-tryptophan. For diabetic neuropathy the NNT for effectiveness was 1.3 (95%CI 1.2 to 1.5) RR 12.4(95%CI 5.2-29.2) (five studies); for postherpetic neuralgia 2.2 (95%CI 1.7 to 3.1), RR 4.8(95%CI 2.5-9.5)(three studies). There was evidence that TCAs are not effective in HIV-related neuropathies. The number needed to harm(NNH) for major adverse effects defined as an event leading to withdrawal from a study was 16 (95%CI: 10-45). The NNH for minor adverse effects was 4.6 (95%CI 3.3-6.7)

AUTHORS' CONCLUSIONS

Antidepressants are effective for a variety of neuropathic pains. The best evidence available is for amitriptyline. There are only limited data for the effectiveness of SSRIs. It is not possible to identify the most effective antidepressant until more studies of SSRIs are conducted.

Carbamazepine for acute and chronic pain

BACKGROUND

Anticonvulsant drugs have been used in the management of pain since the 1960s. The clinical impression is that they are useful for chronic neuropathic pain, especially when the pain is lancinating or burning.

OBJECTIVES

To evaluate the analgesic effectiveness and adverse effects of the anticonvulsant medicine carbamazepine for pain management in clinical practice and to identify a clinical research agenda. Migraine and headache studies are not included in this review.

SEARCH STRATEGY

Randomised trials (RCTs) of anticonvulsants in acute, chronic or cancer pain were identified by MEDLINE (1966-2004), EMBASE (1994-2004), SIGLE (1980-2004) and the Cochrane Controlled Trials Register (CENTRAL/CCTR) (Cochrane Library Issue 3, 2003). In addition, 41 medical journals were hand searched for a previous version of this review. Additional reports were identified from the reference list of the retrieved papers, and by contacting investigators. Date of most recent search: November 2004.

SELECTION CRITERIA

Randomised trials reporting the analgesic effects of carbamazepine in patients, with subjective pain assessment as either the primary or a secondary outcome.

DATA COLLECTION AND ANALYSIS

Data were extracted by two independent reviewers, and trials were quality scored. Numbers-needed-to-treat (NNTs) were calculated from dichotomous data for effectiveness, adverse effects and drug-related study withdrawal, for individual studies and for pooled data.

MAIN RESULTS

Twelve studies were included (404 participants). Four studies included trigeminal neuralgia patients. Two studies which provided evaluable data yielded an NNT for effectiveness of 1.8 (95%CI 1.4-2.8). For diabetic neuropathy there was insufficient data for an NNT to be calculated.Numbers-needed-to-harm (NNHs) were calculated where possible by combining studies for each drug entity irrespective of the condition treated. The results were, for minor harm, carbamazepine 3.7 (CI 2.4-7.8), NNHs for major harm were not statistically significant for carbamazepine compared with placebo. There is no evidence that carbamazepine is effective for acute pain.

AUTHORS' CONCLUSIONS

There is evidence to show that carbamazepine is effective but trials are small.

Pharmacological strategies in relieving neuropathic pain

The pharmacological treatment of neuropathic pain relies, to a large extent, on drugs belonging to a small number of defined classes. Opioids, tricyclic antidepressants, antiepileptic drugs and membrane stabilisers form the current basis of treatment. Varying levels of evidence support the use of individual members of these classes and overall show no indication that one class of drug, or individual drug has universal effectiveness. More refined knowledge of the modes of action of these agents used to treat neuropathic pain should lead to a more logical approach to the management of this difficult series of conditions. A number of drugs currently licensed for a different indication have recently had an analgesic effect in neuropathic pain attributed to them. In addition, a number of novel compounds are undergoing investigation and provide hope of dicovering more efficacious treatment options in the future.

Practical considerations in the assessment and treatment of pain in adults with physical disabilities

Adults aging with physical disabilities experience a variety of pain disorders that affect their functionality and QOL. It is important that clinicians caring for this population be knowledgeable about this common symptom and be able to perform a thorough history and physical examination. In addition, it is imperative to have a good working knowledge of the strengths and limitations of the treatments available.

TDM-Based Imipramine Treatment in Neuropathic Pain

Tricyclic antidepressants (TCA) are the best-documented treatment of neuropathic pain. TCAs have a pronounced interindividual pharmacokinetic variability and a narrow therapeutic index. The aim of this study was to characterize the plasma concentration-effect relationship of imipramine in neuropathic pain and to determine the usefulness of therapeutic drug monitoring (TDM) of TCA treatment in a population with noncancer chronic pain. To do this, 83 patients with chronic noncancer neuropathic pain were included. Information on previous use of TCA was collected, and patients were tested for the presence of hyperalgesia. Pain intensity and pain relief were recorded, and the Short Form McGill Pain Questionnaire and Major Depression Inventory were completed before and during a TDM-based imipramine treatment. Imipramine dose was increased in steps of 25 mg/d every second week, and blood samples were taken at every dose. Endpoints were best possible pain relief, unacceptable side effects, or insufficient pain relief despite plasma drug level > 500 nmol/L. Dose range used was 10-300 mg/d. The study showed that imipramine 75 mg/d caused a 36-fold interindividual variation in steady-state plasma drug concentrations. In 46 responders (global pain relief > 25%) the plasma drug concentration at which an individual maximal analgesic effect was obtained ranged from 50 to 1400 nmol/L, but for the majority it was below 400 nmol/L. The concentration-effect relationship was similar for patients with central versus peripheral neuropathic pain and independent of the presence of hyperalgesia. Previous treatment failure with non-TDM TCA treatment was not a predictor of poor response to TDM-based treatment. In conclusion, there is a pronounced interindividual variability in concentration-effect relationship for imipramine treatment in neuropathic pain, but the majority of patients obtain a maximal analgesic effect at drug levels below 400 nmol/L. The concentration-effect relationship is similar for patients with central and peripheral neuropathic pain. Further studies are needed to document if TDM improves pain relief; however, TDM reduces the risk for toxicity.

Therapeutic outcome in neuropathic pain: relationship to evidence of nervous system lesion

Treatment outcome in patients with neuropathic pain (NP) is often variable and disappointing. We tested the hypothesis that patients with clear evidence of nervous system lesion respond better to pharmacological treatment with documented effect on NP than patients with poor or no evidence of nervous system lesion. Furthermore, we examined whether specific symptoms or signs were associated with treatment outcome. A total of 214 patients with suspected non-cancer NP were divided into four groups with graded evidence of nervous system lesion based on medical history, bedside sensory examination, quantitative sensory tests, electrophysiology, and neuroimaging. Patients were treated with imipramine guided by plasma-drug concentrations. Gabapentin 2400 mg/day was given in case of treatment failure or if imipramine treatment was not possible. Two hundred patients completed the study. Global pain relief was similar in the four groups. There was no association between evidence of nervous system lesion and treatment outcome. Classical NP signs: abnormal temporal summation, cold and brush allodynia, and abnormal sensibility to temperature were also unrelated to outcome. Treatment outcome was similar in peripheral and central definite NP. Neither definite evidence of nervous system lesion nor abnormal sensory phenomena seems to predict for good outcome of therapy with imipramine or gabapentin in patients with suspected neuropathic pain.

Post-stroke pain case study: clinical characteristics, therapeutic options and long-term follow-up

Central post-stroke pain (CPSP) is a syndrome characterized by sensory disturbances and neuropathic pain. In 40%-60% of CPSP patients, the onset of central pain following a stroke occurs more than 1 month after the stroke, creating a source of diagnostic uncertainty or significant delay in treatment since healthcare providers familiar with CPSP may no longer be caring for the patient when the symptoms occur. In addition to chronic pain, the presence of somatosensory abnormalities is the most important diagnostic corollary of CPSP. Neuropathic or central pain has been estimated to occur in up to 8% of patients after a stroke, and about 18% of stroke patients with a somatosensory disturbance will develop CPSP. Although largely a matter of conjecture, it is generally agreed that damage to spinothalamic sensory pathways plays a significant role in the pathogenesis of CPSP. A comprehensive examination of the patient for sensory deficits is essential before treatment can be initiated. Functional disturbances such as depression, anxiety and sleep disturbances are significant comorbid conditions associated with CPSP; the physician should incorporate an assessment of these potential comorbidities into the examination. Treatment options for CPSP are limited; at present, amitriptyline is the drug of first choice. Other drugs including antidepressants, anticonvulsants, antiarrhythmics, opioids and N-methyl-d-aspartate antagonists may provide relief for some patients who do not respond to amitriptyline. Included in this review is a case study outlining the challenges of managing the patient with CPSP.

Pharmacologic Management Part 2: Lesser-Studied Neuropathic Pain Diseases

This second part of a review of the pharmacologic management of neuropathic pain diseases describes the current treatment options for three lesser-studied neuropathic syndromes: Central poststroke pain, spinal cord injury, and complex regional pain syndrome II. Diagnosis can be difficult in patients with these syndromes, because the pain experienced is much greater and of a different type than would normally be expected following a stroke or injury to the spinal cord or a peripheral nerve. Even when an accurate and timely diagnosis is made, treatment options are limited and frequently suboptimal. However, the results of published trials do support the use of anticonvulsants and/or tricyclic antidepressants as first-line pharmacotherapy in these three neuropathic pain syndromes. To maximize treatment outcomes, future research must: Continue to more fully elucidate the relationship between the signs and symptoms of pain and the underlying pathophysiology; Delineate the natural history of central poststroke pain, spinal cord injury, and complex regional pain syndrome; Identify patient-related factors that may indicate an increased risk of developing neuropathic pain following stroke or nerve injury; Investigate emerging treatments that target underlying pain mechanisms.

Pain Management in Trauma Patients

Trauma is a major cause of mortality throughout the world. In recent years, major advances have been made in the management of trauma, the end result of which has been reduced mortality and enhanced function. One of these areas is pain control. Improved pain management has not only led to increased comfort in trauma patients, but has also been shown to reduce morbidity and improve long-term outcomes. This review focuses on the treatment of pain in the setting of acute injury and on pain management in trauma patients who go on to develop chronic pain. Emphasis is placed on pharmacologic interventions, invasive and noninvasive pain management techniques, analgesia in challenging patients, and pain control in commonly encountered trauma conditions.

Pharmacological management of neuropathic pain

In health, the nervous system exists in a balance between inhibitory and excitatory influences. This balance may be upset if neural tissue is damaged or irritated and may give rise to neuropathic pain. Such neuropathic pain does not respond consistently to opioid analgesics or NSAIDs and it may therefore be necessary to utilise other therapeutic agents with known activity on either the excitatory or inhibitory components of the pain pathway. These other agents are traditionally considered with reference to their original uses; we still refer to tricyclic antidepressants (TCAs) and anticonvulsant drugs when a consideration of their modes of action may allow more rational use. For example, carbamazepine is related to the TCAs by virtue of its chemical structure and proposed mode of action and yet is still classified as an anticonvulsant drug. With respect to the opioids, increasing evidence points to an analgesic effect in neuropathic pain, although concerns regarding tolerance and dependence still prevent more widespread use. The anticonvulsants comprise a group of compounds possessing anticonvulsant and analgesic properties, but each possesses differing modes of action and so several members of the class should be tried before a conclusion is reached that they, as a whole, are ineffective. TCAs may also have a role in the treatment of neuropathic pain. As with all drugs, if their use is not associated with pain relief in a defined period of time, their use should be terminated. Topical TCAs may also have a role where the area of neuropathic pain is small. Other options, such as SSRIs, membrane stabilisers, capsaicin, baclofen and clonidine may have potential in treating neuropathic pain. The available evidence regarding the efficacy of currently available agents for the treatment of neuropathic pain is sparse. With the knowledge of achieving analgesia, according to the modes of actions of various agents it is hoped that the treatment of this difficult condition may be more logical and successful.

Interventions for treating depression after stroke

BACKGROUND

Depressive and anxiety disorders following stroke are often undiagnosed or inadequately treated. This may reflect difficulties with the diagnosis of abnormal mood among older people with stroke-related disability, but may also reflect uncertainty about the effectiveness of such therapies in this setting.

OBJECTIVES

To determine whether pharmacological, psychological, or electroconvulsive treatment (ECT) of depression in patients with stroke can improve outcome.

SEARCH STRATEGY

The Cochrane Stroke Group Trials Register (last searched June 2003). The Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to September 2002), CINAHL (1982 to September 2002), PsychINFO (1967 to September 2002), Applied Science and Technology Plus (1986 to September 2002), Arts and Humanities Index (1991 to September 2002), Biological Abstracts (1969 to September 2002), General Science Plus (1994 to September 2002), Science Citation Index (1992 to September 2002), Social Sciences Citation Index (1991 to September 2002), and Sociofile (1974 to September 2002). Reference lists from relevant articles and textbooks were searched, and authors of known studies and pharmaceutical companies who manufacture psychotropic medications were contacted.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different types of pharmaceutical agents with placebo, or various forms of psychotherapy with standard care (or attention control), in patients with recent, clinically diagnosed, acute stroke, where treatment was explicitly intended of treat depression.

DATA COLLECTION AND ANALYSIS

Primary analyses focussed on the prevalence of diagnosable depressive disorder at the end of treatment. Secondary outcomes included depression or mood scores on standard scales, disability or physical function, death, recurrent stroke, and adverse effects. We did not pool the data for summary scores. We performed meta-analysis for only some binary endpoints and data on adverse events.

MAIN RESULTS

Nine trials, with 780 participants, were included in the review. Data were available for seven trials of pharmaceutical agents, and two trials of psychotherapy. There were no trials of ECT. The analyses were complicated by the lack of standardised diagnostic and outcome criteria, and differing analytic methods. There was no strong evidence of benefit of either pharmacotherapy or psychotherapy in terms of a complete remission of depression following stroke. There was evidence of a reduction (improvement) in scores on depression rating scales, and an increase in the proportion of participants with anxiety at the end of follow up.

REVIEWERS' CONCLUSIONS

This review found no evidence to support the routine use of pharmacotherapeutic or psychotherapeutic treatment for depression after stroke. More research is required before recommendations can be made about the most appropriate management of depression following stroke.

Interventions for preventing depression after stroke

BACKGROUND

Abnormal mood is an important consequence of stroke and may affect recovery and outcome. However, depression and anxiety are often not detected or inadequately treated. This may in part be due to doubts about whether anti-depressant treatments commenced early after the onset of stroke will prevent depression and improve outcome.

OBJECTIVES

To determine if pharmaceutical or psychological interventions can prevent the onset of depression, including depressive illness and abnormal mood, and improve physical and psychological outcomes, in patients with stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (June 2003). In addition we searched the following electronic databases: Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2002), MEDLINE (1966 to September 2002), EMBASE (1980 to September 2002), CINAHL (1982 to September 2002), PsychINFO (1967 to September 2002), Applied Science and Technology Plus (1986 to September 2002), Arts and Humanities Index (1991 to September 2002), Biological Abstracts (1969 to September 2002), General Science Plus (1994 to September 2002), Science Citation Index (1992 to September 2002), Social Sciences Citation Index (1991 to September 2002), and Sociofile (1974 to September 2002). Reference lists from relevant articles and textbooks were searched, and authors of known studies and pharmaceutical companies who manufacture psychotropic medications were contacted.

SELECTION CRITERIA

Randomised and quasi-randomised controlled trials comparing different types of pharmaceutical agents (eg selective serotonin reuptake inhibitors) with placebo, or various forms of psychotherapy against standard care (or attention control), in patients with a recent clinical diagnosis of stroke, where the treatment was undertaken with the explicit intention of preventing depression.

DATA COLLECTION AND ANALYSIS

The primary analyses focussed on the proportion of patients who met the standard diagnostic criteria for depression applied in the trials at the end of follow-up. Secondary outcomes included depression or mood scores on standard scales, disability or physical function, death, recurrent stroke, and adverse effects.

MAIN RESULTS

Twelve trials involving 1245 participants were included in the review. Data were available for nine trials (11 comparisons) involving different pharmaceutical agents, and three trials of psychotherapy. The time from stroke onset to entry ranged from a few hours to six months, but most patients were recruited within one month of acute stroke. The duration of treatments ranged from two weeks to one year. There was no clear effect of pharmacological therapy on the prevention of depression or on other measures. A significant improvement in mood was evident for psychotherapy, but this treatment effect was small and from a single trial. There was no effect on diagnosed depression.

REVIEWERS' CONCLUSIONS

This review identified a small but significant effect of psychotherapy on improving mood, but no effect of either pharmacotherapy or psychotherapy on the prevention of depressive illness, disability, or other outcomes. More evidence is therefore required before any recommendations can be made about the routine use of such treatments to improve recovery after stroke.

Quality of the stroke rehabilitation research

The Stroke Rehabilitation Evidence-Based Review revealed a wide range of quality scores across primary studies. The aim of this section is to determine what differences there are across studies and to provide a detailed examination of methodological issues in the stroke rehabilitation literature. Methodology of each article was assessed using the Physiotherapy Evidence Database (PEDro) quality scale. Mean PEDro scores and percentage of studies meeting individual PEDro criteria were determined for all studies, for therapy-based studies only, and for drug-based studies only. It was noted that the stroke rehabilitation literature lacked rigor in the area of concealed allocation, blinding of the assessor, and intention-to-treat analysis. Investigation of the methodological quality of stroke rehabilitation literature emphasizes the need for improved treatment protocols, taking into account previous deficits, during research.

An East-West approach to the management of central post-stroke pain

The development of neuropathic pain following stroke is not uncommon. The consequences include significant disabilities and depression. Treatment can often be difficult and responses unsatisfactory. We report a patient with severe central post-stroke pain (CPSP) of the right leg benefiting from a combination of Western multidisciplinary therapies AND acupuncture. A literature search has revealed that relatively few studies have been done on the management of CPSP, compared with other types of neuropathic pain. Amitriptyline and carbamazepine were found to produce positive effects on post-stroke pain in one small study; lamotrigine and gabapentin are two newer drugs which appear promising. To the best of our knowledge, the use of acupuncture for the treatment of CPSP has not been previously reported.

Treatment of chronic mechanical spinal pain with intravenous pamidronate: a review of medical records

We explored the effect of intravenous infusions of a bisphosphonate, pamidronate, in the management of chronic mechanical spinal pain, a worldwide public health problem in terms of lost workdays, medical treatment costs, and suffering. Bisphosphonates have an anti-nociceptive effect in animals. In humans, intravenous pamidronate relieves numerous painful conditions, including metastatic bone pain, ankylosing spondylitis, rheumatoid arthritis, and complex regional pain syndrome. We reviewed the charts of 25 patients who had experienced disabling spinal pain for several years, and whom we treated with intravenous pamidronate. None had a history of osteoporotic vertebral fractures or metastatic disease. Pain rating scores decreased in 91% of patients: on a 0-10 numeric rating scale, the mean pain change was -3.6 points and mean percentage change was -41% (P<0.0001). There was no increase in opioid or nonopioid analgesic medications associated with pain relief. The apparent analgesic effect of pamidronate for chronic mechanical spinal pain needs to be confirmed with placebo-controlled trials.

Author's experience of lateral medullary infarction--thermal perception and muscle allodynia

The patient, the author (S.K.), is a 67-year-old male. He has the typical dissociated pain, altered temperature sensation and ataxia often encountered by patients with lateral medullary infarction. This started at the time of his admission to hospital. Several weeks after discharge, he experienced the withdrawal reaction to high temperature, first mentioned by Rousseaux (Stroke 30 (1999) 2223), and movement allodynia as described by Bowsher (J Neurol Neurosurg Psychiatry 61 (1996) 62). The article describes his personal experience of the symptoms of central post-stroke pain and allodynia. A difference between muscle allodynia and conventional allodynia caused by dermal stimulation is proposed. Follow-up evaluation of sensory symptoms that appear several weeks after discharge is essential to ensure measures to alleviate them are provided.

Management strategies for the treatment of neuropathic pain in the elderly

Pain caused by dysfunction or damage to the peripheral or central nervous system is typified by the symptoms described by patients with painful diabetic neuropathy, post-herpetic neuralgia and central poststroke pain. All these conditions are more common in the elderly. Neuropathic pain has long been recognised as one of the more difficult types of pain to treat; however, with the current emphasis on providing a multidisciplinary assessment and approach to management, more patients will be offered relief of their symptoms and an improved quality of life. Despite the use of combination drug therapy, adequate pain relief in the elderly is difficult to achieve without adverse effects. In an attempt to minimise these it is important to include non-drug treatment options in the management plan. Lifestyle changes and environmental modification, together with encouragement to adopt an appropriate exercise programme and an emphasis on maintaining mobility and independence should always be considered. Interventional therapy ranging from simple nerve blocks to intrathecal drug delivery can be of value. Drug treatment remains the mainstay of therapy. Tricyclic antidepressants such as amitriptyline, while having significant adverse effects in the elderly, have a number needed to treat (NNT) of 3.5 for 50% pain relief in diabetic neuropathy and 2.1 for 50% pain relief in postherpetic neuralgia. The newer antiepileptic drugs, such as gabapentin, appear to have a better adverse effect profile and provide similar efficacy with the NNT for treating painful diabetic neuropathy being 3.7 and 3.2 for treating pain in postherpetic neuralgia. As our understanding of the complexities of the pain processes increases, we are becoming more able to appropriately combine treatments to achieve not only improved pain relief but also improved function.

Clinically important changes in acute pain outcome measures: a validation study

The purpose of this study was to validate the changes in acute pain measurement scales that are most strongly associated with a patient-determined indicator of clinical importance. Measures of pain intensity and pain relief are commonly used outcomes in therapeutic clinical trials. Recent studies of the properties of acute pain measures have provided data defining the cut-off points that are best associated with clinically important differences. Validation of these findings in another clinical trial data set is important. Data were obtained from the titration phase of a recently conducted randomized controlled clinical trial of oral transmucosal fentanyl citrate (OTFC), which compared OTFC to immediate release morphine sulfate (MSIR) for the treatment of cancer-related acute breakthrough pain. Changes in pain intensity and pain relief were recorded every 15 minutes for 60 minutes and global medication performance recorded at the end of each study pain episode. At any titration step, if the patient felt that the first dose of the study medication did not provide adequate relief within 30 minutes, an additional rescue medication could be taken. To find the level of each pain scale best associated with this measure of the adequacy of pain relief, the calculated sensitivity, specificity, and accuracy for different cut-off points of the measured pain scales were compared to whether or not the patient needed rescue medication. The overall ability of the pain measures to discriminate episodes for which a rescue was not needed was calculated using area under the receiver operating characteristics (ROC) curves. Data were analyzed from 134 OTFC-naive patients who collected data on 1307 episodes of breakthrough pain. Using the criteria of a balanced sensitivity and specificity, the best cut-off points were determined to be: 33% for the percent pain intensity difference; > or =2 for the raw pain intensity difference on a 0-10 numeric rating scale; > or =2 (i.e., moderate or better) for pain relief; > or =33% for the percent maximum total pain relief; and > or =2 (good or better) for global medication performance. ROC area under the curve ranged from 0.839 to 0.862 for each of the pain measures listed above, calculated at 60 minutes. These data indicate that the pain scale cut-off points that are best associated with a patient-derived measure of a clinically important difference closely approximate those found in an earlier study. ROC analysis provided evidence that the overall pain measures were strongly associated with not requiring an "additional dose of rescue medication." Thus, the cut-off points determined for these pain scales provide a good surrogate measure of a patient-determined clinically important response. This provides support for the usefulness of these values in future clinical trials of pain therapy.

Management of stroke

This article outlines the current evidenced based practice for stroke care. It outlines many of the recommendations in the National Clinical Guidelines for Stroke published by the Royal College of Physicians. It also covers all aspects of multidisciplinary stroke care from initial assessment and acute treatment to rehabilitation strategies and management of complications. The article concludes with an examination of the latest evidence for secondary prevention of cerebrovascular disease.

Poststroke shoulder pain: a prospective study of the association and risk factors in 152 patients from a consecutive cohort of 205 patients presenting with stroke

BACKGROUND AND PURPOSE

Shoulder pain is known to retard rehabilitation after stroke. Its causes and prognosis are uncertain. This study describes the incidence of poststroke shoulder pain prospectively, in an unselected stroke population in the first 6 months after stroke and identifies risk factors for developing pain.

METHODS

297 patients with possible stroke were screened and stroke diagnosed in 205 cases. The 152 patients entered the study of which 123 patients were assessed up to 6 months. This cohort, with a mean age of 70.6 years, was examined at 2 weeks, 2, 4, and 6 months. A history of shoulder pain, Barthel score, anxiety and depression score were recorded. Full neurological and rheumatological examination was undertaken, using the contralateral side as a control. Pain outcome and stroke outcome was recorded at subsequent visits.

RESULTS

52 (40%) patients developed shoulder pain on the same side of their stroke. There was a strong association between pain and abnormal shoulder joint examination, ipsilateral sensory abnormalities and arm weakness. Shoulder pain had resolved or improved at 6 months in 41 (80%) of the patients with standard current treatment.

CONCLUSIONS

Shoulder pain after stroke occurred in 40% of 123 patients surviving, consenting and not too unwell to participate. This included 52 patients of an original cohort of 205 patients presenting with stroke. Eighty percent of patients made a good recovery with standard treatment Patients with sensory and or motor deficits represent at risk sub-groups.

Amitriptyline in the prophylaxis of central poststroke pain. Preliminary results of 39 patients in a placebo-controlled, long-term study

BACKGROUND AND PURPOSE

We performed a double-blind, placebo-controlled study to investigate the effectiveness of amitriptyline for the prophylactic treatment of patients with acute thalamic stroke in preventing central poststroke pain.

METHODS

Subject received, in a randomized sequence, either amitriptyline titrated from 10 to 75 mg in extended-release form or placebo over a therapy period of 365 days. We documented the time when pain developed; the intensity, type, site, and distribution of pain; and the presence/absence and type of allodynia.

RESULTS

Thirty-nine patients (23 women and 16 men; age range, 36 to 68 years) with central poststroke pain participated. The placebo group showed a pain rate of 21% within 1 year after the diagnosis of thalamic stroke compared with 17% in the group under prophylactic treatment with amitriptyline. Average (SE) time to pain was 318 (23) days for patients in the placebo group and 324 (24) days for patients in the amitriptyline group.

CONCLUSIONS

With the achieved sample sizes of this study and a pain rate of approximately 21% in the placebo group, any near-perfect pain protection would have been detected. Near-perfect pain protection, in this context, refers to pain in <2.4% of the recruited patients treated with amitriptyline or in approximately 89% of placebo-treated patients. Larger studies are recommended to test the hypothesis that prophylactic amitriptyline reduces but does not completely prevent central poststroke pain.

Anticonvulsants in central pain

Treatment of central neuropathic pain (CP) following lesions of the CNS is a great challenge to the clinician. Preclinical and clinical studies indicate that neuronal hyperexcitability in damaged areas of the central nervous system plays a major role in the development of CP. Anticonvulsants are thought to act by increasing gamma-aminobutyric acid-mediated inhibition, decreasing abnormal neuronal hyperexcitability by modulating sodium and calcium channels or by inhibiting excitatory amino acid actions. The resulting inhibition of excess neuronal activity is thought to be the basis for the use of anticonvulsants in epilepsy as well as neuropathic pain. Both first-generation anticonvulsant drugs (e.g., phenytoin, benzodiazepines, valproate and carbamazepine) and second-generation anticonvulsant drugs (e.g., lamotrigine, gabapentin and topiramate) are used in CP conditions. However, few randomised controlled trials on the treatment of this condition have been published. Present suggestions for anticonvulsant treatment of CP are lamotrigine as the first choice, followed by gabapentin or carbamazepine/oxcarbazepine. These compounds are considered as effective as the antidepressant amitriptyline.

Central pain

PURPOSE OF REVIEW

As a result of its accompanying co-morbidity, our lack of understanding regarding its mechanisms, and its resistance to conventional treatment, central pain is one of the most formidable challenges pain physicians are faced with. The objective of this review is to summarize recent advances in our understanding of the etiology, clinical presentation, and treatment of central pain, with special emphasis being placed on studies published within the past year.

RECENT FINDINGS

Recent evidence suggests that not only injuries commonly associated with central pain, such as strokes and spinal cord lesions, but also disorders such as fibromyalgia, phantom limb pain and tension-type headaches may involve central phenomena. Perhaps because of the lack of clinical trials, treatment is still largely based on traditional prescribing methods and anecdotal evidence. Recent studies have indicated possible roles for tricyclic antidepressants, anti-seizure medications, and motor cortex stimulation in the treatment of central pain.

SUMMARY

Injury to the spinothalamocortical pathways is a necessary, but not sufficient factor in the pathogenesis of central pain. Perhaps because of the similarities in mechanisms, there is considerable overlap between effective treatments for central pain and those for peripheral neuropathic pain. Our poor understanding of the etiology of central pain and the relative lack of effective treatments emphasize the need for further research into this elusive disorder.