Reversible nonfluent aphasia and left frontal hypoperfusion during topiramate treatment

Pharmacotherapy for post-stroke aphasia: what are the options?

INTRODUCTION

Aphasia is a common, long-lasting aftermath of stroke lesions. There is an increased integration of pharmacotherapy as an adjunctive strategy to speech and language therapy (SLT) for post-stroke aphasia (PSA). Nevertheless, more research in pharmacotherapy for acute and chronic PSA is necessary, including the election of drugs that target different neurotransmitter systems and deficits in specific language domains.

AREAS COVERED

This article updates the role of pharmacotherapy for PSA, focusing the spotlight on some already investigated drugs and candidate agents deserving of future research. Refining the precision of drug election would require using multimodal biomarkers to develop personalized treatment approaches. There is a solid need to devise feasible randomized controlled trials adapted to the particularities of the PSA population. The emergent role of multimodal interventions combining one or two drugs with noninvasive brain stimulation to augment SLT is emphasized.

EXPERT OPINION

Pharmacotherapy can improve language deficits not fully alleviated by SLT. In addition, the 'drug-only' approach can also be adopted when administering SLT is not possible. The primary goal of pharmacotherapy is reducing the overall aphasia severity, although targeting language-specific deficits (i.e. naming, spoken output) also contributes to improving functional communication. Unfortunately, there is still little information for recommending a drug for specific language deficits.

Diagnosing and managing post-stroke aphasia

Introduction: Aphasia is a debilitating language disorder and even mild forms of aphasia can negatively affect functional outcomes, mood, quality of life, social participation, and the ability to return to work. Language deficits after post-stroke aphasia are heterogeneous. Areas covered: The first part of this manuscript reviews the traditional syndrome-based classification approach as well as recent advances in aphasia classification that incorporate automatic speech recognition for aphasia classification. The second part of this manuscript reviews the behavioral approaches to aphasia treatment and recent advances such as noninvasive brain stimulation techniques and pharmacotherapy options to augment the effectiveness of behavioral therapy. Expert opinion: Aphasia diagnosis has largely evolved beyond the traditional approach of classifying patients into specific syndromes and instead focuses on individualized patient profiles. In the future, there is a great need for more large scale randomized, double-blind, placebo-controlled clinical trials of behavioral treatments, noninvasive brain stimulation, and medications to boost aphasia recovery.

An update on medications and noninvasive brain stimulation to augment language rehabilitation in post-stroke aphasia

INTRODUCTION

Aphasia is among the most debilitating outcomes of stroke. Aphasia is a language disorder occurring in 10-30% of stroke survivors. Speech and Language Therapy (SLT) is the gold standard, mainstay treatment for aphasia, but gains from SLT may be incomplete. Pharmaceutical and noninvasive brain stimulation (NIBS) techniques may augment the effectiveness of SLT. Areas covered: Herein reviewed are studies of the safety and efficacy of these adjunctive interventions for aphasia, including randomized placebo-controlled and open-label trials, as well as case series from Pubmed, using search terms 'pharmacological,' 'tDCS' or 'TMS' combined with 'aphasia' and 'stroke.' Expert commentary: Relatively small studies have included participants with a range of aphasia types and severities, using inconsistent interventions and outcome measures. Results to-date have provided promising, but weak to moderate evidence that medications and/or NIBS can augment the effects of SLT for improving language outcomes. We end with recommendations for future approaches to studying these interventions, with multicenter, double-blind, randomized controlled trials.

Altered cerebral activity associated with topiramate and its withdrawal in patients with epilepsy with language impairment: An fMRI study using the verb generation task

OBJECTIVE

Topiramate (TPM) is well recognized for its negative effects on language in healthy volunteers and patients with epilepsy. The aim of this study was to investigate the brain activation and deactivation patterns in TPM-treated patients with epilepsy with language impairment and their dynamic alteration during TPM withdrawal using functional magnetic resonance imaging (fMRI) with the verb generation task (VGT).

METHODS

Twelve patients with epilepsy experiencing subjective language disfluency after TPM add-on treatment (TPM-on) and thirty sex- and age-matched healthy controls (HCs) were recruited. All subjects received a battery of neuropsychological tests and an fMRI scan with the VGT. Withdrawal of TPM was attempted in all patients. Only six patients reached complete withdrawal without seizure relapses (TPM-off), and these patients underwent a reassessment of neuropsychological and neuroimaging tests.

RESULT

The neuropsychological tests demonstrated objective language impairments in TPM-on patients. Compared with the HCs, the bilateral medial prefrontal cortex and the posterior midline and lateral parts of the default mode network (DMN) (including the bilateral posterior cingulate cortex (PCC), the right medial prefrontal cortex, the right angular gyrus, the right inferior temporal gyrus, and the bilateral supramarginal gyrus) in TPM-on patients failed to deactivate during the VGT. Their task-induced activation patterns were largely similar to those of the HCs. After TPM withdrawal, partial improvement of both task-induced deactivation of the DMN (the left parahippocampal gyrus and the bilateral PCC) and task-related activation of the language network (the right middle frontal gyrus and the left superior occipital gyrus) was identified along with partial improvement of neuropsychological tests.

CONCLUSION

Task-induced deactivation is a more sensitive neuroimaging biomarker for the impaired language performance in patients administered TPM than task-induced activation. Disruption and reorganization of the balance between the DMN and the cortical language networks are found along with reversible TPM-related language impairment. These results may suggest an underlying brain mechanism by which TPM affects cognitive function.

Topiramate and cognitive impairment: evidence and clinical implications

Topiramate is an antiepileptic drug (AED) with multiple mechanisms of action that has been shown to be effective in a number of neuropsychiatric disorders. However, cognitive dysfunction is frequently observed in such patients, often representing a relevant challenge in their management. Moreover, there is a long-held recognition that AEDs may profoundly affect cognitive functions. This paper reviews available data on cognitive adverse events in patients with neurological disorders treated with topiramate, discussing the role of different contributing factors such as the pharmacological properties of the drug, the specific features of the brain disorder, and other variables pertinent to the discussion. All studies agree that up to 10% of patients may complain of treatment-emergent adverse events on cognition. Such problems occur early during treatment (i.e. within 6 weeks) and emerge in a dose-dependent fashion, suggesting that such prevalence may be significantly reduced using the drug in monotherapy and adopting individualized doses and titration schedules. The magnitude of the problem is generally mild to moderate and the subjective perception of the patient needs to be taken into account. In fact, apart from language problems, data are not conclusive. Comparisons with new AEDs are limited to levetiracetam and lamotrigine, in both cases generally disfavoring topiramate, while data regarding first-generation AEDs show clear differences only for verbal fluency.

Familial vulnerability to an unusual cognitive adverse effect of topiramate: Discussion of mechanisms

BACKGROUND

Some patients experience cognitive disturbances with topiramate.

CASE HISTORIES

A 19-year-old bipolar woman and her 46-year-old mother with paranoid personality disorder both used topiramate (25-50 mg/day) off-label for weight loss. Both women suffer from learning disorders, and both are excessively sensitive to the sedative adverse effects of psychotropic medications.

RESULTS

Within days of starting topiramate, the women began to exhibit troublesome word- and phrase-repetition and word substitution, both occurring only in their written expression. The symptoms were associated with mild sedation, persisted during two weeks of topiramate treatment, and remitted days after topiramate was withdrawn.

DISCUSSION

The presence of the learning disorders and the sensitivity to the sedative adverse effects of drugs may explain why cognitive adverse effects, known to occur with topiramate, developed at the low dose of 25-50 mg/day. The proclivity of topiramate to affect language functions and a possible familial vulnerability herein may explain why the women explained similar, language-specific symptoms. An investigation of topiramate-induced cognitive impairments in family members with epilepsy may throw light on the subject.

Altered language processing in autosomal dominant partial epilepsy with auditory features

BACKGROUND

Autosomal dominant partial epilepsy with auditory features (ADPEAF) is an idiopathic focal epilepsy syndrome with auditory symptoms or receptive aphasia as major ictal manifestations, frequently associated with mutations in the leucine-rich, glioma inactivated 1 (LGI1) gene. Although affected subjects do not have structural abnormalities detected on routine MRI, a lateral temporal malformation was identified through high resolution MRI in one family. We attempted to replicate this finding and to assess auditory and language processing in ADPEAF using fMRI and magnetoencephalography (MEG).

METHODS

We studied 17 subjects (10 affected mutation carriers, 3 unaffected carriers, 4 noncarriers) in 7 ADPEAF families, each of which had a different LGI1 mutation. Subjects underwent high-resolution structural MRI, fMRI with an auditory description decision task (ADDT) and a tone discrimination task, and MEG. A control group comprising 26 volunteers was also included.

RESULTS

We found no evidence of structural abnormalities in any of the 17 subjects. On fMRI with ADDT, subjects with epilepsy had significantly less activation than controls. On MEG with auditory stimuli, peak 2 auditory evoked field latency was significantly delayed in affected individuals compared to controls.

CONCLUSIONS

These findings do not support the previous report of a lateral temporal malformation in autosomal dominant partial epilepsy with auditory features (ADPEAF). However, our fMRI and magnetoencephalography data suggest that individuals with ADPEAF have functional impairment in language processing.