Socioeconomic status in adulthood of children with and without a history of seizures: A retrospective cohort study.

OBJECTIVE: Compare adulthood socioeconomic status for children with and without a history of seizures. METHODS: Retrospective cohort study using Aberdeen Children of the Nineteen Fifties (ACONF) data comprising children born 1950-1956 attending primary school 1962-1964, with follow-up data collected in 2001. Adulthood socioeconomic status was based on registrar general measure of occupational social class and categorised as high or low. We adjusted for potentially confounding variables including childhood socioeconomic status, behavioural issues (Rutter A/B scores), biological sex, school test scores, educational attainment, parental engagement with education, peer-status in school, and alcohol use in adulthood. A multivariate binary logistic regression was performed to estimate the adjusted association between children with a history of seizures of any type (for example febrile seizures, or provoked seizures of any other etiology or seizures in the context of epilepsy) or severity and adult socioeconomic status. Multiple imputation using the Monte-Carlo-Markov-Chain method accounted for missing data. RESULTS: Pooled estimates (N = 2,208) comparing children with a history of seizures (n = 81) and children without a history of seizures (n = 2,127) found no differences between these cohorts in terms of adulthood socioeconomic status in both unadjusted (Odds Ratio (OR) 1.45 [95 % CI 0.71-2.96], p = 0.31) and adjusted (1.02 [0.46, 2.24], p = 0.96) analyses. Compared to males, females were at increased odds of having a lower socioeconomic status in adulthood (1.56 [1.13-2.17], p = 0.01).Compared to those with low educational attainment, those with moderate (0.32 [0.21, 0.48], p < 0.001) and high (0.12 [0.07, 0.20], p < 0.001) educational attainment were at reduced odds of having a lower socioeconomic status in adulthood. CONCLUSION: Cognitive problems in childhood (using educational attainment and scores on primary school tests proxy markers for cognition) rather than a history of seizures per se, were associated with lower SES in a population of adults born 1950-56 in Aberdeen. This relationship may be different depending on the time in history and nation/region of study. Given the changes in health, education and social support in the management of children with seizures over time, it would be of interest to investigate outcomes in a contemporary cohort. Such studies should ideally have validated diagnoses of seizures, details on seizure characteristics such as seizure type and severity, and a large sample size using national data.

Real-world experience with the new Watchman FLX device: Data from two high-volume Sicilian centers. The FLX-iEST registry.

INTRODUCTION: The Watchman-FLX left atrial appendage closure (LAAC) device presents innovative features: higher conformability, reduced length, closed distal "flex-ball" during deployment, and flattened surface. We report our real-world experience with the Watchman-FLX device in two centers with consolidated LAAC expertise. METHODS: We enrolled 200 consecutive Watchman-FLX patients (2019-2021) in a nonrandomized double-center registry; procedural data and follow-up for midterm clinical outcomes were collected. A control group of 100 patients treated with first-generation Watchman (2.5) was included. RESULTS: According to mean CHAD2 DS2 -VASc (5 ± 1.40) and HAS-BLED (3.8 ± 1.01) scores, the population included in this study was at high risk: 29% had a previous stroke and 56.5% a bleeding event. Main LAAC indications were symptomatic hemorrhage (39.5%), need for triple antithrombotic therapy (39%), gastrointestinal bleeding (32%), and oral anticoagulation intolerance (18%). Transesophageal echocardiography guidance was followed in 93% of cases (48% in general anesthesia and 45% under conscious sedation). Repositioning an FLX device was required in 20% of cases and no complication occurred. In 96% of patients, the first selected device was delivered, while in 4% a device size change was required after the first choice (7% with Watchman 2.5). Peridevice leaks (<5 mm) were found postimplant in two cases (1%). Overall, the procedural success rate was 99.5%. One patient's procedure was unsuccessful (0.5%), due to left atrial appendage (LAA) anatomy; differently, the mean failure rate with Watchman 2.5 was 2%. No device embolization was reported. Complications (8.5%) were mainly related to the access site (3%); major bleedings (1%), and in-hospital death (0.5%) rarely occurred. After a follow-up of 272 ± 173 days, 2.3% of cases experienced a non-device-related stroke and 0.6% fatal bleeding. CONCLUSION: Our registry showed a high procedural success rate of the Watchman-FLX in a high-risk population. According to our experience, the main advantages include easy implanting and repositioning, absence of embolization, good LAA sealing, and low rate of complications in the follow-up period.

Measuring quality of life in Duchenne muscular dystrophy: a systematic review of the content and structural validity of commonly used instruments.

Duchenne muscular dystrophy (DMD) is an inherited X-linked neuromuscular disorder. A number of questionnaires are available to assess quality of life in DMD, but there are concerns about their validity. This systematic review aimed to appraise critically the content and structural validity of quality of life instruments for DMD. Five databases (EMBASE, MEDLINE, CINAHL, PsycINFO, and Cochrane Library) were searched, with supplementary searches in Google Scholar. We included articles with evidence on the content and/or structural validity of quality of life instruments in DMD, and/or instrument development. Evidence was evaluated against the Consensus-based Standards for the selection of health Measurement INstruments (COSMIN) criteria. Fifty five articles featured a questionnaire assessing quality of life in DMD. Forty instruments were extracted and 26 underwent assessment. Forty-one articles contained evidence on content or structural validity (including 37 development papers). Most instruments demonstrated low quality evidence and unsatisfactory or inconsistent validity in DMD, with the majority not featuring direct validation studies in this population. Only KIDSCREEN received an adequate rating for instrument design and a satisfactory result for content validity based on its development, yet, like the majority of PROMs, the measure has not been directly validated for use in DMD. Further research is needed on the validity of quality of life instruments in DMD, including content and structural validity studies in this population.

Mechanisms of action underlying the efficacy of deep brain stimulation of the subthalamic nucleus in Parkinson's disease: central role of disease severity.

Despite consensus on some neurophysiological hallmarks of the Parkinsonian state (such as beta) band increase) a single mechanism is unlikely to explain the efficacy of deep brain stimulation (DBS) of the subthalamic nucleus (STN). Most experimental evidence to date correlates with an extreme degree of nigral neurodegeneration and not with different stages of PD progression. It seems inappropriate to combine substantially different patients - newly diagnosed, early fluctuators or advanced dyskinetic individuals - within the same group. An efficacious STN-DBS imposes a new activity pattern within brain circuits, favouring alpha- and gamma-like neuronal discharge, and restores the thalamo-cortical transmission pathway through axonal activation. In addition, stimulation via the dorsal contacts of the macro-electrode may affect cortical activation antidromically. However, basal ganglia (BG) modulation remains cardinal for 'OFF'-'ON' transition (as revealed by cGMP increase occurring during STN-DBS in the substantia nigra pars reticulata and internal globus pallidus). New research promises to clarify to what extent STN-DBS restores striato-centric bidirectional plasticity, and whether non-neuronal cellular actions (microglia, neurovascular) play a part. Future studies will assess whether extremely anticipated DBS or lesioning in selected patients are capable of providing neuroprotection to the synuclein-mediated alterations of synaptic efficiency. This review addresses these open issues through the specific mechanisms prevailing in a given disease stage. In patients undergoing early protocol, alteration in endogenous transmitters and recovery of plasticity are concurrent players. In advanced stages, re-modulation of endogenous band frequencies, disruption of pathological pattern and/or antidromic cortical activation are, likely, the prominent modes.

Our first decade of experience in deep brain stimulation of the brainstem: elucidating the mechanism of action of stimulation of the ventrolateral pontine tegmentum.

The region of the pedunculopontine tegmental nucleus (PPTg) has been proposed as a novel target for deep brain stimulation (DBS) to treat levodopa resistant symptoms in motor disorders. Recently, the anatomical organization of the brainstem has been revised and four new distinct structures have been represented in the ventrolateral pontine tegmentum area in which the PPTg was previously identified. Given this anatomical reassessment, and considering the increasing of our experience, in this paper we revisit the value of DBS applied to that area. The reappraisal of clinical outcomes in the light of this revisitation may also help to understand the consequences of DBS applied to structures located in the ventrolateral pontine tegmentum, apart from the PPTg. The implantation of 39 leads in 32 patients suffering from Parkinson's disease (PD, 27 patients) and progressive supranuclear palsy (PSP, four patients) allowed us to reach two major conclusions. The first is that the results of the advancement of our technique in brainstem DBS matches the revision of brainstem anatomy. The second is that anatomical and functional aspects of our findings may help to explain how DBS acts when applied in the brainstem and to identify the differences when it is applied either in the brainstem or in the subthalamic nucleus. Finally, in this paper we discuss how the loss of neurons in brainstem nuclei occurring in both PD and PSP, the results of intraoperative recording of somatosensory evoked potentials, and the improvement of postural control during DBS point toward the potential role of ascending sensory pathways and/or other structures in mediating the effects of DBS applied in the ventrolateral pontine tegmentum region.

Pedunculopontine Nucleus Region Deep Brain Stimulation in Parkinson Disease: Surgical Techniques, Side Effects, and Postoperative Imaging.

The pedunculopontine nucleus (PPN) region has received considerable attention in clinical studies as a target for deep brain stimulation (DBS) in Parkinson disease. These studies have yielded variable results with an overall impression of improvement in falls and freezing in many but not all patients treated. We evaluated the available data on the surgical anatomy and terminology of the PPN region in a companion paper. Here we focus on issues concerning surgical technique, imaging, and early side effects of surgery. The aim of this paper was to gain more insight into the reasoning for choosing specific techniques and to discuss shortcomings of available studies. Our data demonstrate the wide range in almost all fields which were investigated. There are a number of important challenges to be resolved, such as identification of the optimal target, the choice of the surgical approach to optimize electrode placement, the impact on the outcome of specific surgical techniques, the reliability of intraoperative confirmation of the target, and methodological differences in postoperative validation of the electrode position. There is considerable variability both within and across groups, the overall experience with PPN DBS is still limited, and there is a lack of controlled trials. Despite these challenges, the procedure seems to provide benefit to selected patients and appears to be relatively safe. One important limitation in comparing studies from different centers and analyzing outcomes is the great variability in targeting and surgical techniques, as shown in our paper. The challenges we identified will be of relevance when designing future studies to better address several controversial issues. We hope that the data we accumulated may facilitate the development of surgical protocols for PPN DBS.

Pedunculopontine Nucleus Region Deep Brain Stimulation in Parkinson Disease: Surgical Anatomy and Terminology.

Several lines of evidence over the last few years have been important in ascertaining that the pedunculopontine nucleus (PPN) region could be considered as a potential target for deep brain stimulation (DBS) to treat freezing and other problems as part of a spectrum of gait disorders in Parkinson disease and other akinetic movement disorders. Since the introduction of PPN DBS, a variety of clinical studies have been published. Most indicate improvements in freezing and falls in patients who are severely affected by these problems. The results across patients, however, have been variable, perhaps reflecting patient selection, heterogeneity in target selection and differences in surgical methodology and stimulation settings. Here we outline both the accumulated knowledge and the domains of uncertainty in surgical anatomy and terminology. Specific topics were assigned to groups of experts, and this work was accumulated and reviewed by the executive committee of the working group. Areas of disagreement were discussed and modified accordingly until a consensus could be reached. We demonstrate that both the anatomy and the functional role of the PPN region need further study. The borders of the PPN and of adjacent nuclei differ when different brainstem atlases and atlas slices are compared. It is difficult to delineate precisely the PPN pars dissipata from the nucleus cuneiformis, as these structures partially overlap. This lack of clarity contributes to the difficulty in targeting and determining the exact localization of the electrodes implanted in patients with akinetic gait disorders. Future clinical studies need to consider these issues.

Two distinct interneuron circuits in human motor cortex are linked to different subsets of physiological and behavioral plasticity.

How does a single brain region participate in multiple behaviors? Here we argue that two separate interneuron circuits in the primary motor cortex (M1) contribute differently to two varieties of physiological and behavioral plasticity. To test this in human brain noninvasively, we used transcranial magnetic stimulation (TMS) of M1 hand area to activate two independent sets of synaptic inputs to corticospinal neurons by changing the direction of current induced in the brain: posterior-to-anterior current (PA inputs) and anterior-to-posterior current (AP inputs). We demonstrate that excitability changes produced by repetitive activation of AP inputs depend on cerebellar activity and selectively alter model-based motor learning. In contrast, the changes observed with repetitive stimulation of PA inputs are independent of cerebellar activity and specifically modulate model-free motor learning. The findings are highly suggestive that separate circuits in M1 subserve different forms of motor learning.

Comparison of neurodevelopmental, educational and adult socioeconomic outcomes in offspring of women with and without epilepsy: A systematic review and meta-analysis.

BACKGROUND: Adequate pre-pregnancy counselling and education planning are essential to improve outcomes for offspring of women with epilepsy (OWWE). The current systematic review and meta-analysis aimed to compare outcomes for OWWE and offspring of women without epilepsy (OWWoE). METHODS: We conducted a systematic review and meta-analysis. We searched MEDLINE, EMBASE, CINAHL, PsycINFO (database inception-1st January 2023), OpenGrey, GoogleScholar, and hand-searched journals and reference lists of included studies to identify eligible studies. We placed no language restrictions and included observational studies concerning OWWE and OWWoE. We followed the PRIMSA checklist for abstracting data. The Newcastle-Ottawa Scale for risk of bias assessment was conducted independently by two authors with mediation by a third. We report pooled unadjusted odds ratios (OR) or mean differences (MD) with 95% confidence intervals (95CI) from random (I2>50%) or fixed (I2<50%) effects meta-analyses. Outcomes of interest included offspring autism, attention deficit/hyperactive disorder, intellectual disability, epilepsy, developmental disorder, intelligence, educational, and adulthood socioeconomic outcomes. RESULTS: Of 10,928 articles identified, we included 21 in meta-analyses. OWWE had increased odds of autism (2 articles, 4,502,098 offspring) OR [95CI] 1·67 [1·54, 1·82], attention-deficit/hyperactivity disorder (3 articles, 957,581 offspring) 1·59 [1·44, 1·76], intellectual disability (2 articles, 4,501,786 children) 2·37 [2·13, 2·65], having special educational needs (3 articles, 1,308,919 children) 2·60 [1·07, 6·34]. OWWE had worse mean scores for full-scale intelligence (5 articles, 989 children) -6·05 [-10·31, -1·79]. No studies were identified that investigated adulthood socioeconomic outcomes. CONCLUSIONS: Increased odds of poor outcomes are higher with greater anti-seizure medication burden including neurodevelopmental and educational outcomes. In fact, these two outcomes seem to be worse in OWWE compared to OWWoE, even if there was no ASM exposure during pregnancy, but further work is needed to take into account potential confounding factors.

Microcircuit mechanisms involved in paired associative stimulation-induced depression of corticospinal excitability.

Synaptic weight changes induced by temporal correlations between the spikes of pre- and postsynaptic neurons are referred to as spike-timing-dependent plasticity (STDP). Transcranial magnetic stimulation (TMS) induces long-lasting effects on corticospinal excitability, if it is repetitively paired with stimulation of afferents from a corresponding contralateral hand region at short intervals (paired associative stimulation, PAS). PAS-induced plasticity has been linked with synaptic STDP. We aimed to investigate which elements of the cortical microcircuitry sustain and govern PAS-induced depression of corticospinal excitability in the target muscle representation (and enhancement of excitability in its functional surround). We show that the time window during which the interaction between both stimulus-induced cortical events leads to immediate post-interventional depression is short (<4.5 ms). The depressant PAS effects at the target representation were completely blocked by applying a subthreshold magnetic pulse 3 ms before the principal TMS pulse, even when the strength of the latter was adjusted to generate a motor-evoked potential of similar amplitude to that with the unconditioned magnetic pulse. Epidural recordings from the cervical cord of a patient showed that under this condition late TMS-evoked I-waves remain suppressed. When the intensity of the TMS component during PAS was lowered - sufficient to allow activation of inhibitory neurons, but insufficient to activate corticospinal neurons - excitability of short-latency intracortical inhibition remained unchanged. PAS-induced facilitation in the functional surround followed the same pattern as the centre-depressant effects. These findings may suggest that excitability-depressant PAS-induced effects are due to weakening of excitatory synapses between upper cortical layer principal neurons, but not those located on the corticospinal neuron, or inhibitory synapses. Inhibitory interneurons involved in short-latency intracortical inhibition are gate-keepers to producing centre-depressant/surround-facilitatory PAS effects. Based on these and earlier findings we propose a model specifying the composition and laminar location of the involved microcircuit of PAS-induced plasticity that may enhance its utility as a model of STDP in humans.

Dual Antiplatelet Therapy with Parenteral P2Y12 Inhibitors: Rationale, Evidence, and Future Directions.

Dual antiplatelet therapy (DAPT), consisting of the combination of aspirin and an inhibitor of the platelet P2Y12 receptor for ADP, remains among the most investigated treatments in cardiovascular medicine. While a substantial amount of research initially stemmed from the observations of late and very late stent thrombosis events in the first-generation drug-eluting stent (DES) era, DAPT has been recently transitioning from a purely stent-related to a more systemic secondary prevention strategy. Oral and parenteral platelet P2Y12 inhibitors are currently available for clinical use. The latter have been shown to be extremely suitable in drug-naïve patients with acute coronary syndrome (ACS), mainly because oral P2Y12 inhibitors are associated with delayed efficacy in patients with STEMI and because pre-treatment with P2Y12 inhibitors is discouraged in NSTE-ACS, and in patients with recent DES implantation and in need of urgent cardiac and non-cardiac surgery. More definitive evidence is needed, however, about optimal switching strategies between parenteral and oral P2Y12 inhibitors and about newer potent subcutaneous agents that are being developed for the pre-hospital setting.

A Multimodality Imaging for Definition and Treatment Selection of Multiple Coronary Aneurysms: A Case Report and Review of the Literature.

A 59-year-old woman, smoker, hypertensive, without a previous history of coronary artery disease referred several episodes of epigastric pain, after exercise electrocardiogram was referred to coronary angiography. It revealed extensive coronary calcification, with a suboccluded left anterior descending (LAD) and a calcified aneurysm of the right coronary artery (RCA), partially filled with thrombus. Coronary-computed tomography showed aneurysmal saccular dilatation of the proximal LAD entirely thrombosed with subocclusion, and a fusiform aneurysm in the proximal RCA, partially thrombosed. The patient was referred for surgical treatment. In our patient, congenital etiology of the aneurysms was unlikely, since the patient did not present congenital heart disease or known genetically inherited disorders. Among acquired aneurysms, the most common cause is represented by atherosclerosis. Other potential causes are connective tissue disorders, trauma, infections, iatrogenic, and Kawasaki syndrome. Usual complications include myocardial ischemia and infarction, embolism, rupture, fistulization, and thrombosis (clearly represented in our case). Current recommendations about management strategies of coronary artery aneurysms (CAAs) are focused on small case series and based on aneurysm's location and morphology, patient's characteristics, and clinical presentation. Medical treatment strategies include antiplatelet therapy or anticoagulant. Other therapeutical options are percutaneous coronary intervention (PCI) and coronary artery bypass graft. In our case, the heart team opted for surgical treatment due to the subocclusion of the proximal LAD and considering stable angina as admitting diagnosis. Moreover, the CAAs were placed in proximal segments, with a large amount of thrombus, so related with high risk for complications if PCI was performed.

Comparison of Perinatal Outcomes for Women With and Without Epilepsy: A Systematic Review and Meta-analysis.

Importance: Pregnant women who have epilepsy need adequate engagement, information, and pregnancy planning and management to improve pregnancy outcomes. Objective: To investigate perinatal outcomes in women with epilepsy compared with women without epilepsy. Data Sources: Ovid MEDLINE, Embase, CINAHL, and PsycINFO were searched with no language or date restrictions (database inception through December 6, 2022). Searches also included OpenGrey and Google Scholar and manual searching in journals and reference lists of included studies. Study Selection: All observational studies comparing women with and without epilepsy were included. Data Extraction and Synthesis: The PRISMA checklist was used for abstracting data and the Newcastle-Ottawa Scale for risk-of-bias assessment. Data extraction and risk-of-bias assessment were done independently by 2 authors with mediation conducted independently by a third author. Pooled unadjusted odds ratios (OR) or mean differences were reported with 95% CI from random-effects (I2 heterogeneity statistic >50%) or fixed-effects (I2 < 50%) meta-analyses. Main Outcomes and Measures: Maternal, fetal, and neonatal complications. Results: Of 8313 articles identified, 76 were included in the meta-analyses. Women with epilepsy had increased odds of miscarriage (12 articles, 25 478 pregnancies; OR, 1.62; 95% CI, 1.15-2.29), stillbirth (20 articles, 28 134 229 pregnancies; OR, 1.37; 95% CI, 1.29-1.47), preterm birth (37 articles, 29 268 866 pregnancies; OR, 1.41; 95% CI, 1.32-1.51) and maternal death (4 articles, 23 288 083 pregnancies; OR, 5.00; 95% CI, 1.38-18.04). Neonates born to women with epilepsy had increased odds of congenital conditions (29 articles, 24 238 334 pregnancies; OR, 1.88; 95% CI, 1.66-2.12), neonatal intensive care unit admission (8 articles, 1 204 428 pregnancies; OR, 1.99; 95% CI, 1.58-2.51), and neonatal or infant death (13 articles, 1 426 692 pregnancies; OR, 1.87; 95% CI, 1.56-2.24). The increased odds of poor outcomes was increased with greater use of antiseizure medication. Conclusions and Relevance: This systematic review and meta-analysis found that women with epilepsy have worse perinatal outcomes compared with women without epilepsy. Women with epilepsy should receive pregnancy counseling from an epilepsy specialist who can also optimize their antiseizure medication regimen before and during pregnancy.

A Comprehensive Overview of Vision Screening Programmes across 46 Countries.

Purpose: To describe and compare vision screening programmes and identify variance in number and type of tests used, timing of screening, personnel involved, monitoring and funding to be used as data for optimising, disinvesting or implementing future screening programmes. Methods: A questionnaire consisting of nine domains: demography & epidemiology, administration & general background, existing screening, coverage & attendance, tests, follow-up & diagnosis, treatment, cost & benefit and adverse effects was completed by Country Representatives (CRs) recruited from 47 countries. Results: The questionnaire was sufficiently completed for 46 Countries: 42 European countries, China, India, Malawi and Rwanda. Variation of provision was found in; age of screening (0-17 years), tests included (23), types of visual acuity (VA) test used (35 different optotypes), personnel (13), number of screens per child (median 5, range 1-32), and times VA tested (median 3, range 1-30). Infant screening is offered in all countries, whereas childhood vision screening is offered at least once in all countries, but not all regions of each country. All 46 countries provide vision screening between the ages of 3-7 years. Data on screening outcomes for quality assurance was not available from most countries; complete evaluation data was available in 2% of countries, partial data from 43%. Conclusion: Vision screening is highly variable. Some form of VA testing is being undertaken during childhood. Data collection and sharing should be improved to facilitate comparison and to be able to optimise vision screening programmes between regions and countries.

Transcranial direct current stimulation effects on I-wave activity in humans.

Transcranial direct current stimulation (tDCS) of the human cerebral cortex modulates cortical excitability noninvasively in a polarity-specific manner: anodal tDCS leads to lasting facilitation and cathodal tDCS to inhibition of motor cortex excitability. To further elucidate the underlying physiological mechanisms, we recorded corticospinal volleys evoked by single-pulse transcranial magnetic stimulation of the primary motor cortex before and after a 5-min period of anodal or cathodal tDCS in eight conscious patients who had electrodes implanted in the cervical epidural space for the control of pain. The effects of anodal tDCS were evaluated in six subjects and the effects of cathodal tDCS in five subjects. Three subjects were studied with both polarities. Anodal tDCS increased the excitability of cortical circuits generating I waves in the corticospinal system, including the earliest wave (I1 wave), whereas cathodal tDCS suppressed later I waves. The motor evoked potential (MEP) amplitude changes immediately following tDCS periods were in agreement with the effects produced on intracortical circuitry. The results deliver additional evidence that tDCS changes the excitability of cortical neurons.

The deep brain stimulation of the pedunculopontine tegmental nucleus: towards a new stereotactic neurosurgery.

The application of deep brain stimulation (DBS) to the pedunculopontine tegmental nucleus (PPTg) has required profound modifications of classic neurosurgical techniques and of the criteria for evaluation of clinical results. This review analyzes a novel method of targeting the PPTg, based on angio-computerized tomography (angio-CT) scans and the tridimensional reconstruction of nuclei and cerebral vessels, and considers the advantages of applying these methods in comparison to the more traditional approach based on reference points obtained through the evaluation of the bicommessural line. Validation of the results obtained following unilateral PPTg DBS through neurophysiological recordings and objective measurements of functional parameters suggests that the PPTg may be considered as an initial target for the treatment of motor symptoms in selected patients affected by idiopathic Parkinson's disease (PD), which, if required, could be followed by DBS of other target areas. Moreover, on the basis of the observations derived from stimulating the PPTg, the potential utility attributed up to date to intraoperative neurophysiological recordings for identifying neurosurgical targets should be revisited, and the need for changes in the intraoperative management of patients has arisen from the body of evidence accumulated over recent years. The results obtained by different groups following PPTg DBS in parkinsonian patients are not uniform, most likely due to a cautious acceptance of this methodology, the experience progressively acquired, the criteria for patient selection and to subtle differences in target location. Although the role of PPTg in PD and/or in other pathologies remains to be clarified, pursuing the traditional approach on classical basal ganglia targets may limit the perspective of DBS based on multiple implantations.

The pedunculopontine tegmental nucleus: implications for a role in modulating spinal cord motoneuron excitability.

There is evidence that deep brain stimulation (DBS) of the pedunculopontine tegmental nucleus (PPTg) improves parkinsonian motor signs. The mechanisms that mediate these effects and the modifications that occur in the PPTg in Parkinson's disease (PD) are not fully known and are the object of current debate. The aim of this paper was to critically review available data with respect to (1) the presence of PPTg neurons linked to reticulospinal projections, (2) the involvement of these neurons in modulating spinal reflexes, and (3) the participation of fibers close to or within the PPTg region in such modulation. The PPTg neurons are distributed in a large pontotegmental region, stimulation of which can evoke activity in hindlimb, shoulder and neck muscles, and potentiate motor responses evoked by stimulation of dorsal roots. This influence seems to be carried out by fast-conducting descending fibers, which likely run in the medial reticulospinal pathway. It is yet unclear which neurotransmitters are involved and on which elements of the gray matter of the spinal cord PPTg fibers synapse. The modulation of spinal cord activity which can be achieved by stimulating the PPTg region seems to be mediated not only by PPTg neurons, but also by tecto-reticular fibers which run in the pontotegmental area, and which likely are activated during PPTg-DBS. The importance of these fibers is discussed taking into account the degeneration of PPTg neurons in PD and the benefits in gait and postural control that PPTg-DBS exerts in PD. The potential usefulness of PPTg-DBS in other neurodegenerative disorders characterized by neuronal loss in the brainstem is also considered.

Contribution of different somatosensory afferent input to subcortical somatosensory evoked potentials in humans.

OBJECTIVES: To investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents. METHODS: SEPs were recorded in 6 patients suffering from Parkinson's disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed. RESULTS: After median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts. CONCLUSIONS: Stimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential. SIGNIFICANCE: Our results shed light on the subcortical processing of the somatosensory input of different modalities.

Pedunculopontine tegmental Nucleus-evoked prepulse inhibition of the blink reflex in Parkinson's disease.

OBJECTIVE: To investigate the effects on the blink reflex (BR) of single stimuli applied to the pedunculopontine tegmental nucleus (PPTg). METHODS: The BR was evoked by stimulating the supraorbital nerve (SON) in fifteen patients suffering from idiopathic Parkinson's disease (PD) who had electrodes monolaterally or bilaterally implanted in the PPTg for deep brain stimulation (DBS). Single stimuli were delivered to the PPTg through externalized electrode connection wires 3-4 days following PPTg implantation. RESULTS: PPTg stimuli increased the latency and reduced duration, amplitude and area of the R2 component of the BR in comparison to the response recorded in the absence of PPTg stimulation. These effects were independent of the side of SON stimulation and were stable for interstimulus interval (ISI) between PPTg prepulse and SON stimulus from 0 to 110 ms. The PPTg-induced prepulse inhibition of the BR was bilaterally present in the brainstem. The R1 component was unaffected. CONCLUSIONS: The prepulse inhibition of the R2 component may be modulated by the PPTg. SIGNIFICANCE: These findings suggest that abnormalities of BR occurring in PD may be ascribed to a reduction of basal ganglia-mediated inhibition of brainstem excitability.