Cognitive Impairment in MRI-Negative Epilepsy: Relationship between Neurophysiological and Neuropsychological Measures.

BACKGROUND: Epileptic patients frequently encounter cognitive impairment. Functions that are mostly affected involve memory, attention, and executive function; however, this is mainly dependent on the location of the epileptic activity. The aim of the present study is to assess cognitive functions in MRI-negative epilepsy patients by means of neurophysiological and neuropsychological measures, as well as study the concept of transient cognitive impairment in patients with epileptiform discharges during EEG acquisition. METHODS: The patients were enrolled from an outpatient Epilepsy/Clinical Neurophysiology clinic over a time period of 6 months. The study sample comprised 20 MRI-negative epilepsy patients (mean age ± standard deviation (SD), 30.3 ± 12.56 years; age range, 16-60 years; average disease duration, 13.95 years) and 10 age-matched controls (mean age ± SD, 24.22 ± 15.39 years), who were also education-matched (p > 0.05). Patients with epileptogenic lesions were excluded from the study. Informed consent was obtained from all subjects involved in the study. Auditory ERPs and the cognitive screening tool EpiTrack were administered to all subjects. RESULTS: Latencies of P300 and slow waves were prolonged in patients compared to controls (p < 0.05). The ASM load and patients' performance in the EpiTrack maze subtest were the most significant predictors of P300 latency. A decline in the memory, attention, and speed of information processing was observed in patients with cryptogenic epilepsy compared to age-matched controls, as reflected by P300 latency and EpiTrack scores.

Biomarkers of disease progression in adolescents and adults with 5q spinal muscular atrophy: a systematic review and meta-analysis.

Since the introduction of disease modifying treatments there is an unmet need to identify biomarkers of spinal muscular atrophy (SMA) natural history. We performed a systematic review and meta-analysis to summarize available evidence. We searched MEDLINE, Embase, Cochrane Library and gray literature until February 2021. The primary outcome was biomarkers longitudinal course in adolescents and adults. The secondary outcome was the discrimination of patients from controls. We included 42 records examining 606 patients from 19 population cohorts over a maximum follow-up of 17-years. Lung function and serum biomarkers could not depict disease progression. We identified potential biomarkers of disease activity [SMA functional rating scale, MoviPlate, pinch strength, compound muscle action potential (CMAP), motor unit number estimation (MUNE)] that require further investigation. Data regarding Hammersmith functional motor scale expanded, Revised upper limb module, 6-minute walk test were contradictory impeding any pooled estimate. The pooled analysis regarding our secondary outcome revealed that upper limb CMAP amplitudes and MUNE mean values differed significantly between SMA patients and controls [mean difference -3.63(-6.2, -1.06), -119.74(-153.93, -85.56) respectively]. Given the lack of natural history data on this population, our qualitative synthesis and meta-analysis could provide valuable evidence and identify promising predictive biomarkers requiring further longitudinal examination. PROSPERO Registration: CRD42021235605.

Intrathecal Administration of Nusinersen Using the Ommaya Reservoir in an Adult with 5q-Related Spinal Muscular Atrophy Type 1 and Severe Spinal Deformity.

Spinal muscular atrophy (SMA) is a hereditary neuromuscular disorder, typically caused by survival motor neuron 1 (SMN1) gene deletion in chromosome 5q resulting in loss of SMN protein. SMA type 1 progresses rapidly leading to increased mortality usually before the age of 2 years. Nusinersen, the first approved disease-modifying treatment for all 5q-SMA types and ages, is an antisense oligonucleotide administered intrathecally via repeated lumbar punctures. However, adult SMA patients typically present with severe scoliosis and spinal deformity. We present a 28-year-old patient with SMA type 1 and severe spinal deformity, who received nusinersen via a subcutaneously implanted Ommaya reservoir connected with an intrathecal catheter at the thoracic level. The repetitive administrations were completed uneventfully, obviating the need for repeated laborious lumbar punctures and eliminating radiation exposure. In adult SMA patients, performing recurrent lumbar punctures can be technically challenging raising the need for an alternative route of administration. The use of Ommaya reservoirs is a viable, practical for repeated infusions, and safe option for the intrathecal delivery of nusinersen for select cases such as an adult SMA type 1 survivor with severe spinal deformity.

Differential effects of lacosamide, phenytoin and topiramate on peripheral nerve excitability: An ex vivo electrophysiological study.

BACKGROUND: Antiepileptic drugs (AEDs) are mainly used to control cortical hyperexcitability. Some of them (e.g. phenytoin (PHT) and topiramate (TPM)) have also effects on the peripheral nervous system (PNS). Lacosamide (LCM) is a novel AED that stabilizes hyperexcitable neuronal membranes by selectively enhancing the slow inactivation of voltage-gated sodium channels (VGSCs). Although the mechanism of action of LCM is fairly well understood, there are no in vitro data available regarding any possible PNS effects of LCM. OBJECTIVE: To investigate, in vitro, the effects of LCM on peripheral nerve excitability in comparison with PHT and TPM, two AEDs that act, in part, by stabilizing the fast inactivation state of VGSCs. METHODS: Experiments were conducted on the isolated sciatic nerve of the adult rat using standard electrophysiological methods. The effects of LCM on the amplitude and latency of the evoked compound action potential (CAP) during a 48h period of drug exposure were recorded and compared with the effects of PHT and TPM. RESULTS: LCM produced inhibitory effects on CAP at concentrations significantly higher than the therapeutic levels (>25µg/ml). At these concentrations (62.57-125.15µg/ml), an acute and immediate increment of the latency and decrement of the amplitude of the CAP were observed. In contrast to LCM, PHT caused an acute decrement in the amplitude as well as an increment in the latency of the CAP even at subtherapeutic levels (5µg/ml). With regard to TPM, the amplitude of the CAP was not affected at the supratherapeutic concentrations but at the therapeutic concentration of 33.94µg/ml a reduced decrement of the CAP amplitude compared to the controls was observed. CONCLUSIONS: LCM, PHT and TPM exert differential effects on peripheral nerve excitability. PHT inhibited the sciatic nerve CAP even at subtherapeutic levels whereas LCM was safe within the therapeutic concentration range. TPM did not affect the CAP amplitude even at high supratherapeutic concentrations whereas in the therapeutic range a neuroprotective effect was observed. Possible underlying mechanisms and the clinical implications of these findings are discussed.

Assessing the effects of the three herbicides acetochlor, 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) and 2,4-dichlorophenoxyacetic acid on the compound action potential of the sciatic nerve of the frog (Rana ridibunda).

To assess the relative toxicity of the herbicides acetochlor and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) on the nervous system, the sciatic nerve of the frog (Rana ridibunda) nerve was incubated in saline inside a specially designed recording chamber. This chamber permits monitoring of the evoked compound action potential (CAP) of the nerve, a parameter that could be used to quantify the vitality of the nerve in normal conditions as well as when the nerve was exposed to the compounds under investigation. Thus, when the nerve was exposed to acetochlor, the EC(50) was estimated to be 0.22mM, while for 2,4,5-T the EC(50) was 0.90mM. Using the identical nerve preparation, the EC(50) of 2,4-D was estimated to be 3.80mM [Kouri, G., Theophilidis, G., 2002. The action of the herbicide 2,4-dichlorophenoxyacetic acid on the isolated sciatic nerve of the frog (Rana ridibunda). Neurotoxicol. Res. 4, 25-32]. The ratio of the relative toxicity for acetochlor, 2,4,5-T and 2,4-D was found to be 1:4:17.2. However, because it is well-known that the action of 2,4-D is dependent on the pH, the relative toxicity of the three compounds was tested at pH 3.3, since it has been found that the sciatic nerve of the frog is tolerant of such a low pH. Under these conditions, the EC(50) was 0.77mM (from 0.22mM at pH 7.2) for acetochlor, 0.20mM (from 0.90mM) for 2,4,5-T and 0.24mM (from 3.80mM at pH 7.2) for 2,4-D. Thus, the relative toxicity of the three compounds changed drastically to 1:0.25:0.31. This change in the relative toxicity is due not only to the increase in the toxicity of 2,4,5-T and 2,4-D at low pH levels, but also to the decrease in the toxicity of acetochlor at pH 3.3.

The action of the insecticide imidacloprid on the respiratory rhythm of an insect: the beetle Tenebrio molitor.

Imidacloprid is an insecticide which has the nicotinic acetylcholine receptors (nAChRs) as its primary site of action; acetylcholine is the major excitatory neurotransmitter in the insect central nervous system (CNS). In this study, the action of imidacloprid was tested using the synapses of the respiratory central pattern generator of the beetle Tenebrio molitor. The no observed effect concentration (NOEC) for imidacloprid was estimated to be between 0.001 and 0.010 microM. A concentration of 0.10 microM caused hyperexcitation in firing of the respiratory motoneurons, while the concentration of 1.00 microM caused an abrupt increase in their frequency and then a complete inhibition of the activity of the respiratory motoneurons. The possible implication of the action of such low concentrations of imidacloprid in the contraction of the respiratory muscles is also demonstrated and discussed.

Triazines facilitate neurotransmitter release of synaptic terminals located in hearts of frog (Rana ridibunda) and honeybee (Apis mellifera) and in the ventral nerve cord of a beetle (Tenebrio molitor).

Three triazine herbicides, atrazine, simazine and metribuzine, and some of their major metabolites (cyanuric acid and 6-azauracil) were investigated for their action on synaptic terminals using three different isolated tissue preparations from the atria of the frog, Rana ridibunda, the heart of the honeybee, Apis mellifera macedonica, and the ventral nerve cord of the beetle, Tenebrio molitor. The results indicate that triazines facilitate the release of neurotransmitters from nerve terminals, as already reported for the mammalian central nervous system. The no observed effect concentration, the maximum concentration of the herbicide diluted in the saline that has no effect on the physiological properties of the isolated tissue, was estimated for each individual preparation. According to their relative potency, the three triazines tested can be ranked as follows: atrazine (cyanuric acid), simazine>metribuzine (6-azauracil). The action of these compounds on the cholinergic (amphibians, insects), adrenergic (amphibian) and octopaminergic (insects) synaptic terminals is discussed.