Delayed onset post-traumatic wound botulism.

A 41-year-old man developed rapidly progressive cranial neuropathies and muscle weakness followed by respiratory failure, requiring ventilation support. On examination, there was marked bilateral ptosis and ophthalmoplegia with bulbar, neck and proximal upper limb weakness. He had a recent open left humeral fracture that eventually required amputation. Despite immunoglobulin therapy, his progressive weakness continued. Multiple investigation results were inconclusive. Eventually, botulinum type A toxin was found positive, by which time the therapeutic window for antitoxin had passed. He continued on supportive management and was treated for concomitant infections and nosocomial illnesses. He was subsequently weaned from respiratory support and has made a good neurological recovery.

Cerebellar Volume and Disease Staging in Parkinson's Disease: An ENIGMA-PD Study.

BACKGROUND: Increasing evidence points to a pathophysiological role for the cerebellum in Parkinson's disease (PD). However, regional cerebellar changes associated with motor and non-motor functioning remain to be elucidated. OBJECTIVE: To quantify cross-sectional regional cerebellar lobule volumes using three dimensional T1-weighted anatomical brain magnetic resonance imaging from the global ENIGMA-PD working group. METHODS: Cerebellar parcellation was performed using a deep learning-based approach from 2487 people with PD and 1212 age and sex-matched controls across 22 sites. Linear mixed effects models compared total and regional cerebellar volume in people with PD at each Hoehn and Yahr (HY) disease stage, to an age- and sex- matched control group. Associations with motor symptom severity and Montreal Cognitive Assessment scores were investigated. RESULTS: Overall, people with PD had a regionally smaller posterior lobe (dmax = -0.15). HY stage-specific analyses revealed a larger anterior lobule V bilaterally (dmax = 0.28) in people with PD in HY stage 1 compared to controls. In contrast, smaller bilateral lobule VII volume in the posterior lobe was observed in HY stages 3, 4, and 5 (dmax = -0.76), which was incrementally lower with higher disease stage. Within PD, cognitively impaired individuals had lower total cerebellar volume compared to cognitively normal individuals (d = -0.17). CONCLUSIONS: We provide evidence of a dissociation between anterior "motor" lobe and posterior "non-motor" lobe cerebellar regions in PD. Whereas less severe stages of the disease are associated with larger motor lobe regions, more severe stages of the disease are marked by smaller non-motor regions. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neuromelanin-MRI to Quantify and Track Nigral Depigmentation in Parkinson's Disease: A Multicenter Longitudinal Study Using Template-Based Standardized Analysis.

BACKGROUND: Clinical diagnosis and monitoring of Parkinson's disease (PD) remain challenging because of the lack of an established biomarker. Neuromelanin-magnetic resonance imaging (NM-MRI) is an emerging biomarker of nigral depigmentation indexing the loss of melanized neurons but has unknown prospective diagnostic and tracking performance in multicenter settings. OBJECTIVES: The aim was to investigate the diagnostic accuracy of NM-MRI in early PD in a multiprotocol setting and to determine and compare serial NM-MRI changes in PD and controls. METHODS: In this longitudinal case-control 3 T MRI study, 148 patients and 97 controls were included from six UK clinical centers, of whom 140 underwent a second scan after 1.5 to 3 years. An automated template-based analysis was applied for subregional substantia nigra NM-MRI contrast and volume assessment. A point estimate of the period of prediagnostic depigmentation was computed. RESULTS: All NM metrics performed well to discriminate patients from controls, with receiver operating characteristic showing 85% accuracy for ventral NM contrast and 83% for volume. Generalizability using a priori volume cutoff was good (79% accuracy). Serial MRI demonstrated accelerated NM loss in patients compared to controls. Ventral NM contrast loss was point estimated to start 5 to 6 years before clinical diagnosis. Ventral nigral depigmentation was greater in the most affected side, more severe cases, and nigral NM volume change correlated with change in motor severity. CONCLUSIONS: We demonstrate that NM-MRI provides clinically useful diagnostic information in early PD across protocols, platforms, and sites. It provides methods and estimated depigmentation rates that highlight the potential to detect preclinical PD and track progression for biomarker-enabled clinical trials. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

International Multicenter Analysis of Brain Structure Across Clinical Stages of Parkinson's Disease.

BACKGROUND: Brain structure abnormalities throughout the course of Parkinson's disease have yet to be fully elucidated. OBJECTIVE: Using a multicenter approach and harmonized analysis methods, we aimed to shed light on Parkinson's disease stage-specific profiles of pathology, as suggested by in vivo neuroimaging. METHODS: Individual brain MRI and clinical data from 2357 Parkinson's disease patients and 1182 healthy controls were collected from 19 sources. We analyzed regional cortical thickness, cortical surface area, and subcortical volume using mixed-effects models. Patients grouped according to Hoehn and Yahr stage were compared with age- and sex-matched controls. Within the patient sample, we investigated associations with Montreal Cognitive Assessment score. RESULTS: Overall, patients showed a thinner cortex in 38 of 68 regions compared with controls (dmax  = -0.20, dmin  = -0.09). The bilateral putamen (dleft  = -0.14, dright  = -0.14) and left amygdala (d = -0.13) were smaller in patients, whereas the left thalamus was larger (d = 0.13). Analysis of staging demonstrated an initial presentation of thinner occipital, parietal, and temporal cortices, extending toward rostrally located cortical regions with increased disease severity. From stage 2 and onward, the bilateral putamen and amygdala were consistently smaller with larger differences denoting each increment. Poorer cognition was associated with widespread cortical thinning and lower volumes of core limbic structures. CONCLUSIONS: Our findings offer robust and novel imaging signatures that are generally incremental across but in certain regions specific to disease stages. Our findings highlight the importance of adequately powered multicenter collaborations. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Gabapentin add-on treatment for drug-resistant focal epilepsy.

BACKGROUND: This is an updated version of the Cochrane Review previously published in 2018. Epilepsy is a common neurological disorder characterised by recurrent seizures. Most people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop drug-resistant epilepsy, especially people with focal seizures. In this review, we summarised the evidence from randomised controlled trials (RCTs) of gabapentin, when used as an add-on treatment for drug-resistant focal epilepsy. OBJECTIVES: To evaluate the efficacy and tolerability of gabapentin when used as an add-on treatment for people with drug-resistant focal epilepsy. SEARCH METHODS: For the latest update, we searched the Cochrane Register of Studies (CRS Web) and MEDLINE (Ovid) on 11 August 2020. CRS Web includes randomised or quasi-randomised, controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups including Epilepsy. We imposed no language restrictions. SELECTION CRITERIA: Randomised, placebo-controlled, double-blind, add-on trials of gabapentin in people with drug-resistant focal epilepsy. We also included trials using an active drug control group or comparing different doses of gabapentin. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: seizure frequency, seizure freedom, treatment withdrawal (any reason) and adverse effects. Primary analyses were intention-to-treat. We also undertook sensitivity best-case and worst-case analyses. We estimated summary risk ratios (RR) for each outcome and evaluated dose-response in regression models. MAIN RESULTS: We identified no new studies for this update, therefore, the results and conclusions are unchanged. In the previous update of this review, we combined data from six trials in meta-analyses of 1206 randomised participants. The overall risk ratio (RR) for reduction in seizure frequency of 50% or more compared to placebo was 1.89 (95% confidence interval (CI) 1.40 to 2.55; 6 studies, 1206 participants; moderate-certainty evidence). Dose regression analysis (for trials in adults) showed increasing efficacy with increasing dose, with 25.3% (95% CI 19.3 to 32.3) of people responding to gabapentin 1800 mg compared to 9.7% on placebo, a 15.5% increase in response rate (95% CI 8.5 to 22.5). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49; 6 trials, 1206 participants; moderate-certainty evidence). Adverse effects were significantly associated with gabapentin compared to placebo. RRs were as follows: ataxia 2.01 (99% CI 0.98 to 4.11; 3 studies, 787 participants; low-certainty evidence), dizziness 2.43 (99% CI 1.44 to 4.12; 6 studies, 1206 participants; moderate-certainty evidence), fatigue 1.95 (99% CI 0.99 to 3.82; 5 studies, 1161 participants; low-certainty evidence) and somnolence 1.93 (99% CI 1.22 to 3.06; 6 studies, 1206 participants; moderate-certainty evidence). There was no evidence of a difference for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35; 6 studies, 1206 participants; moderate-certainty evidence) or nausea (RR 0.95, 99% CI 0.52 to 1.73; 4 trials, 1034 participants; moderate-certainty evidence). Overall, the studies were at low to unclear risk of bias due to information on each risk of bias domain not being available. We judged the overall certainty of the evidence (using the GRADE approach) as low to moderate due to potential attrition bias resulting from missing outcome data and imprecise results with wide CIs. AUTHORS' CONCLUSIONS: Gabapentin has efficacy as an add-on treatment in people with drug-resistant focal epilepsy, and seems to be fairly well-tolerated. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of gabapentin beyond a three-month period. The results cannot be extrapolated to monotherapy or to people with other epilepsy types. Further trials are needed to assess the long-term effects of gabapentin, and to compare gabapentin with other add-on drugs.

Blood-Brain Barrier Leakage Is Increased in Parkinson's Disease.

BACKGROUND: Blood-brain barrier (BBB) disruption has been noted in animal models of Parkinson's disease (PD) and forms the basis of the vascular hypothesis of neurodegeneration, yet clinical studies are lacking. OBJECTIVE: To determine alterations in BBB integrity in PD, with comparison to cerebrovascular disease. METHODS: Dynamic contrast enhanced magnetic resonance images were collected from 49 PD patients, 15 control subjects with cerebrovascular disease [control positive (CP)] and 31 healthy control subjects [control negative (CN)], with all groups matched for age. Quantitative maps of the contrast agent transfer coefficient across the BBB (K trans) and plasma volume (v p ) were produced using Patlak analysis. Differences in K trans and v p were assessed with voxel-based analysis as well as in regions associated with PD pathophysiology. In addition, the volume of white matter lesions (WMLs) was obtained from T2-weighted fluid attenuation inversion recovery (FLAIR) images. RESULTS: Higher K trans, reflecting higher BBB leakage, was found in the PD group than in the CN group using voxel-based analysis; differences were most prominent in the posterior white matter regions. Region of interest analysis confirmed K trans to be significantly higher in PD than in CN, predominantly driven by differences in the substantia nigra, normal-appearing white matter, WML and the posterior cortex. WML volume was significantly higher in PD compared to CN. K trans values and WML volume were similar in PD and CP, suggesting a similar burden of cerebrovascular disease despite lower cardiovascular risk factors. CONCLUSION: These results show BBB disruption in PD.

Gabapentin add-on treatment for drug-resistant focal epilepsy.

BACKGROUND: This is an updated version of the Cochrane Review previously published in 2013.Most people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop drug-resistant epilepsy, especially those with focal seizures. In this review, we summarised the evidence from randomised controlled trials (RCTs) of gabapentin, when used as an add-on treatment for drug-resistant focal epilepsy. OBJECTIVES: To evaluate the efficacy and tolerability of gabapentin when used as an add-on treatment for people with drug-resistant focal epilepsy. SEARCH METHODS: For the latest update, we searched the Cochrane Register of Studies (CRS Web, 20 March 2018), which includes the Cochrane Epilepsy Group's Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to 20 March 2018), ClinicalTrials.gov (20 March 2018) and the World Health Organization International Clinical Trials Registry Platform (ICTRP, 20 March 2018). We imposed no language restrictions. SELECTION CRITERIA: Randomised, placebo-controlled, double-blind, add-on trials of gabapentin in people with drug-resistant focal epilepsy. We also included trials using an active drug control group or comparing different doses of gabapentin. DATA COLLECTION AND ANALYSIS: For this update, two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: seizure frequency, seizure freedom, treatment withdrawal (any reason) and adverse effects. Primary analyses were intention-to-treat. We also undertook sensitivity best-case and worst-case analyses. We estimated summary risk ratios (RR) for each outcome and evaluated dose-response in regression models. MAIN RESULTS: We included 12 trials representing 2607 randomised participants. We combined data from six trials in meta-analyses of 1206 randomised participants. The overall RR for reduction in seizure frequency of 50% or more compared to placebo was 1.89 (95% confidence interval (CI) 1.40 to 2.55; 6 trials, 1206 participants; moderate-quality evidence). Dose regression analysis (for trials in adults) showed increasing efficacy with increasing dose, with 25.3% (19.3 to 32.3) of people responding to gabapentin 1800 mg compared to 9.7% on placebo, a 15.5% increase in response rate (8.5 to 22.5). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49; 6 trials, 1206 participants; moderate-quality evidence). Adverse effects were significantly associated with gabapentin compared to placebo. RRs were as follows: ataxia 2.01 (99% CI 0.98 to 4.11; 3 studies, 787 participants; low-quality evidence), dizziness 2.43 (99% CI 1.44 to 4.12; 6 studies, 1206 participants; moderate-quality evidence), fatigue 1.95 (99% CI 0.99 to 3.82; 5 studies, 1161 participants; low-quality evidence) and somnolence 1.93 (99% CI 1.22 to 3.06; 6 studies, 1206 participants; moderate-quality evidence). There were no significant differences for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35; 6 studies, 1206 participants; moderate-quality evidence) or nausea (RR 0.95, 99% CI 0.52 to 1.73; 4 trials, 1034 participants; moderate-quality evidence). Overall, the studies were rated at low to unclear risk of bias due to information on each risk of bias domain not being available. We judged the overall quality of evidence (using the GRADE approach) as low to moderate due to potential attrition bias resulting from missing outcome data and imprecise results with wide confidence intervals. AUTHORS' CONCLUSIONS: Gabapentin has efficacy as an add-on treatment in people with drug-resistant focal epilepsy. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of gabapentin beyond a three-month period. The results cannot be extrapolated to monotherapy or to people with other epilepsy types.

Extracranial arterial wall volume is increased and shows relationships with vascular MRI measures in idiopathic Parkinson's disease.

OBJECTIVE: Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disorder, often complicated by dementia. Cardiovascular risk factors and spontaneous cerebral emboli (SCE) are strongly associated with Alzheimer's (AD) and vascular dementia (VaD). We measured SCE in the middle cerebral artery and arterial wall volume in the extracranial arteries in patients with IPD and controls, and explored the relationships with structural and physiological MRI brain neurovascular measures. PATIENTS AND METHODS: Arterial wall volume over 2cm of the axillary and internal carotid arteries (ICA) bilaterally was measured by 3-D tomographic ultrasound in 15 IPD patients and 16 age/gender matched controls. SCE were counted by Transcranial Doppler (TCD) using international consensus criteria. Venous to arterial circulation shunting (v-aCS), usually through a patent foramen ovale (PFO), was measured using a TCD technique with intravenous microbubble contrast. Structural and physiological MRI brain neurovascular measures, acquired separately, comprised white matter lesion volume (WMLV), cerebral blood flow (CBF) and arterial arrival time (AAT). RESULTS: Mean (95% CI) axillary and ICA wall volume was higher in IPD patients at 523 mm3 (446, 600) and 455 mm3 (374, 536) respectively compared with 412 mm3 (342, 483) and 408 mm3 (362, 454) in controls being significant for the axillary artery (p = 0.04). Cerebral WMLV was related to mean arterial wall volume for both axillary (r = 0.555, p = 0.009) and ICA (r = 0.559, p = 0.026) in all participants. SCE were detected in four IPD patients and three controls (p = 1.00). Two IPD patients and three controls were positive for a v-aCS equivalent to PFO (p = 0.477). CONCLUSION: Although frequent in AD and VaD, neither SCE nor v-aCS were associated with IPD. This is the first study to demonstrate arterial wall volume is increased in IPD and relates to WMLV.

Relapsing cerebral amyloid angiopathy-related inflammation: the wax and the wane.

Cerebral amyloid angiopathy-related inflammation (CAA-I) is a rare variant of cerebral amyloid angiopathy (CAA). Its precise pathophysiology remains uncertain and we currently have limited evidence on which immunosuppressive agents are the most effective in its treatment. The disease course of CAA-I disorders can vary from an isolated clinical event to recurrent episodes. We present a case of biopsy-confirmed CAA-I that gives insight into its potential relapsing nature and the challenges of its long-term management.

Structural and physiological neurovascular changes in idiopathic Parkinson's disease and its clinical phenotypes.

Neurovascular changes are likely to interact importantly with the neurodegenerative process in idiopathic Parkinson's disease (IPD). Markers of neurovascular status (NVS) include white matter lesion (WML) burden and arterial spin labelling (ASL) measurements of cerebral blood flow (CBF) and arterial arrival time (AAT). We investigated NVS in IPD, including an analysis of IPD clinical phenotypes, by comparison with two control groups, one with a history of clinical cerebrovascular disease (CVD) (control positive, CP) and one without CVD (control negative, CN). Fifty-one patients with IPD (mean age 69.0 ± 7.7 years) (21 tremor dominant (TD), 24 postural instability and gait disorder (PIGD) and six intermediates), 18 CP (mean age 70.1 ± 8.0 years) and 34 CN subjects (mean age 67.4 ± 7.6 years) completed a 3T MRI scan protocol including T2-weighted fluid-attenuated inversion recovery (FLAIR) and ASL. IPD patients showed diffuse regions of significantly prolonged AAT, small regions of lower CBF and greater WML burden by comparison with CN subjects. TD patients showed lower WML volume by comparison with PIGD patients. These imaging data thus show altered NVS in IPD, with some evidence for IPD phenotype-specific differences.

Structural and physiological MRI correlates of occult cerebrovascular disease in late-onset epilepsy.

Late-onset epilepsy (LOE), with onset after 50 years of age, is often attributed to underlying occult cerebrovascular disease. LOE is associated with a three-fold increase in subsequent stroke risk, therefore it is important to improve our understanding of pathophysiology. In this exploratory study, we aimed to determine whether established structural magnetic resonance imaging markers and novel physiological imaging markers of occult cerebrovascular disease were more common in patients with LOE than age-matched controls. Sixteen patients with LOE (mean age ± SD: 67.6 ± 6.5 years) and 15 age-matched control subjects (mean age: 65.1 ± 3.9 years) underwent a 3 T MRI scan protocol. T1-weighted images and T2-weighted fluid attenuated inversion recovery (FLAIR) images were used to determine cortical grey matter volume and white matter hyperintensity (WMH) volume respectively, whilst multiple delay time arterial spin labelling (ASL) images were collected at rest and during a hypercapnic challenge. Cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from ASL data under both normocapnic and hypercapnic conditions. Cerebrovascular reactivity was also calculated for both CBF and AAT relative to the change in end-tidal CO2. Patients with LOE were found to have significantly lower cortical volume than control subjects (33.8 ± 3.8% of intracranial volume vs. 38.0 ± 5.5%, p = 0.02) and significantly higher WMH volume (1339 ± 1408 mm3 vs. 514 ± 481 mm3, p = 0.047). Baseline whole brain AAT was found to be significantly prolonged in patients with LOE in comparison to control subjects (1539 ± 129 ms vs. 1363 ± 167 ms, p = 0.005). Voxel-based analysis showed the significant prolongation of AAT to be predominantly distributed in the frontal and temporal lobes. Voxel-based morphometry showed the lower cortical volume to be localised primarily to temporal lobes. No significant differences in CBF or cerebrovascular reactivity were found between the two groups. Baseline whole brain AAT and cortical volume differences persisted upon further analysis to take account of differences in smoking history between patients and control subjects. These findings suggest that occult cerebrovascular disease is relevant to the pathophysiology of LOE.

Arterial spin labelling reveals prolonged arterial arrival time in idiopathic Parkinson's disease.

Idiopathic Parkinson's disease (IPD) is the second most common neurodegenerative disease, yet effective disease modifying treatments are still lacking. Neurodegeneration involves multiple interacting pathological pathways. The extent to which neurovascular mechanisms are involved is not well defined in IPD. We aimed to determine whether novel magnetic resonance imaging (MRI) techniques, including arterial spin labelling (ASL) quantification of cerebral perfusion, can reveal altered neurovascular status (NVS) in IPD. Fourteen participants with IPD (mean ± SD age 65.1 ± 5.9 years) and 14 age and cardiovascular risk factor matched control participants (mean ± SD age 64.6 ± 4.2 years) underwent a 3T MRI scan protocol. ASL images were collected before, during and after a 6 minute hypercapnic challenge. FLAIR images were used to determine white matter lesion score. Quantitative images of cerebral blood flow (CBF) and arterial arrival time (AAT) were calculated from the ASL data both at rest and during hypercapnia. Cerebrovascular reactivity (CVR) images were calculated, depicting the change in CBF and AAT relative to the change in end-tidal CO2. A significant (p = 0.005) increase in whole brain averaged baseline AAT was observed in IPD participants (mean ± SD age 1532 ± 138 ms) compared to controls (mean ± SD age 1335 ± 165 ms). Voxel-wise analysis revealed this to be widespread across the brain. However, there were no statistically significant differences in white matter lesion score, CBF, or CVR between patients and controls. Regional CBF, but not AAT, in the IPD group was found to correlate positively with Montreal cognitive assessment (MoCA) scores. These findings provide further evidence of alterations in NVS in IPD.

Late-onset epilepsy and occult cerebrovascular disease.

The interface between cerebrovascular disease (CVD) and epilepsy is complex and multifaceted. Late-onset epilepsy (LOE) is increasingly common and is often attributed to CVD, and is indeed associated with an increased risk of stroke. This relationship is easily recognizable where there is a history of stroke, particularly involving the cerebral cortex. However, the relationship with otherwise occult, subcortical CVD is currently less well established yet causality is often invoked. In this review, we consider the diagnosis of LOE in clinical practice--including its behaviour as a potential mimic of acute ischemic stroke and transient ischemic attack; evidence for an association between occult CVD and LOE; and potential mechanisms of epileptogenesis in occult CVD, including potential interrelationships between disordered cerebral metabolism and perfusion, disrupted neurovascular unit integrity, blood-brain barrier dysfunction, and inflammation. We also discuss recently recognized issues concerning antiepileptic drug treatment and vascular risk and consider a variety of less common CVD entities associated with seizures.

Gabapentin add-on for drug-resistant partial epilepsy.

BACKGROUND: The majority of people with epilepsy have a good prognosis and their seizures are well controlled by a single antiepileptic drug, but up to 30% develop drug-resistant epilepsy, especially those with partial seizures. In this review we summarise the current evidence regarding the antiepileptic drug gabapentin, when used as an add-on treatment for drug-resistant partial epilepsy. OBJECTIVES: To evaluate the efficacy and tolerability of gabapentin when used as an add-on treatment for people with drug-resistant partial epilepsy. SEARCH METHODS: This is an updated version of the original Cochrane review published in The Cochrane Library 2009, Issue 4. We searched the Cochrane Epilepsy Group's Specialised Register (14 May 2013), the Cochrane Central Register of Controlled Trials (CENTRAL 2013, Issue 4, The Cochrane Library) (April 2013) and MEDLINE (1946 to 14 May 2013). We imposed no language restrictions. SELECTION CRITERIA: Randomised, placebo-controlled, double-blind, add-on trials of gabapentin in people with drug-resistant partial epilepsy. Trials using an active drug control group or which compared doses of gabapentin were also included in the review. DATA COLLECTION AND ANALYSIS: Two review authors independently selected trials for inclusion and extracted the relevant data. We assessed the following outcomes: (a) seizure frequency and seizure freedom; (b) treatment withdrawal (any reason); (c) adverse effects. Primary analyses were intention-to-treat. We also undertook sensitivity best and worst-case analyses. We estimated summary risk ratios for each outcome and evaluated dose-response in regression models. MAIN RESULTS: Eleven trials were included representing 2125 randomised participants. We combined data from six trials in meta-analyses of 1206 randomised participants. The overall risk ratio (RR) for 50% or greater reduction in seizure frequency compared to placebo was 1.89 (95% confidence interval (CI) 1.40 to 2.55). Dose regression analysis (for trials in adults) shows increasing efficacy with increasing dose, with 25.3% (19.3 to 32.3) of people responding to 1800 mg of gabapentin compared to 9.7% on placebo, a 15.5% increase in response rate (8.5 to 22.5). The RR for treatment withdrawal compared to placebo was 1.05 (95% CI 0.74 to 1.49). Adverse effects were significantly associated with gabapentin compared to placebo. Risk ratios were as follows: ataxia 2.01 (99% CI 0.98 to 4.11), dizziness 2.43 (99% CI 1.44 to 4.12), fatigue 1.95 (99% CI 0.99 to 3.82) and somnolence 1.93 (99% CI 1.22 to 3.06). No significant differences were found for the adverse effects of headache (RR 0.79, 99% CI 0.46 to 1.35) or nausea (RR 0.95, 99% CI 0.52 to 1.73). Overall the studies together are rated as low/unclear risk of bias due to information on each risk of bias domain not being available. AUTHORS' CONCLUSIONS: Gabapentin has efficacy as an add-on treatment in people with drug-resistant partial epilepsy. However, the trials reviewed were of relatively short duration and provide no evidence for the long-term efficacy of gabapentin beyond a three-month period. The results cannot be extrapolated to monotherapy or to people with other epilepsy types.