Functional Outcome and Hemorrhage Rates After Bridging Therapy With Tenecteplase or Alteplase in Patients With Large Ischemic Core.

BACKGROUND AND OBJECTIVES: IV tenecteplase is an alternative to alteplase before mechanical thrombectomy (MT) in patients with large-vessel occlusion (LVO) ischemic stroke. Little data are available on its use in patients with large ischemic core. We aimed to compare the efficacy and safety of both thrombolytics in this population. METHODS: We conducted a retrospective analysis of patients with anterior circulation LVO strokes and diffusion-weighed imaging Alberta Stroke Program Early CT Score (DWI-ASPECTS) ≤5 treated with tenecteplase or alteplase before MT from the TETRIS (tenecteplase) and ETIS (alteplase) French multicenter registries. Primary outcome was reduced disability at 3 months (ordinal analysis of the modified Rankin scale [mRS]). Safety outcomes were 3-month mortality, parenchymal hematoma (PH), and symptomatic intracranial hemorrhage (sICH). We used propensity score overlap weighting to reduce baseline differences between treatment groups. RESULTS: We analyzed 647 patients (tenecteplase: n = 194; alteplase: n = 453; inclusion period 2015-2022). Median (interquartile range) age was 71 (57-81) years, with NIH Stroke Scale score 19 (16-22), DWI-ASPECTS 4 (3-5), and last seen well-to-IV thrombolysis and puncture times 165 minutes (130-226) and 260 minutes (203-349), respectively. After MT, the successful reperfusion rate was 83.1%. After propensity score overlap weighting, all baseline variables were well balanced between both treatment groups. Compared with patients treated with alteplase, patients treated with tenecteplase had better 3-month mRS (common odds ratio [OR] for reduced disability: 1.37, 1.01-1.87, p = 0.046) and lower 3-month mortality (OR 0.52, 0.33-0.81, p < 0.01). There were no significant differences between thrombolytics for PH (OR 0.84, 0.55-1.30, p = 0.44) and sICH incidence (OR 0.70, 0.42-1.18, p = 0.18). DISCUSSION: Our data are encouraging regarding the efficacy and reassuring regarding the safety of tenecteplase compared with that of alteplase in bridging therapy for patients with LVO strokes and a large ischemic core in routine clinical care. These results support its consideration as an alternative to alteplase in bridging therapy for patients with large ischemic cores. TRIALS REGISTRATION INFORMATION: NCT03776877 (ETIS registry) and NCT05534360 (TETRIS registry). CLASSIFICATION OF EVIDENCE: This study provides Class III evidence that patients with anterior circulation LVO stroke and DWI-ASPECTS ≤5 treated with tenecteplase vs alteplase before MT experienced better functional outcomes and lower mortality at 3 months.

Early Recanalization Among Patients Undergoing Bridging Therapy With Tenecteplase or Alteplase.

BACKGROUND: Intravenous thrombolysis (IVT) with alteplase or tenecteplase before mechanical thrombectomy is the recommended treatment for large-vessel occlusion acute ischemic stroke. There are divergent data on whether these agents differ in terms of early recanalization (ER) rates before mechanical thrombectomy, and little data on their potential differences stratified by ER predictors such as IVT to ER evaluation (IVT-to-EReval) time, occlusion site and thrombus length. METHODS: We retrospectively compared the likelihood of ER after IVT with tenecteplase or alteplase in anterior circulation large-vessel occlusion acute ischemic stroke patients from the PREDICT-RECANAL (alteplase) and Tenecteplase Treatment in Ischemic Stroke (tenecteplase) French multicenter registries. ER was defined as a modified Thrombolysis in Cerebral Infarction score 2b-3 on the first angiographic run, or noninvasive vascular imaging in patients with early neurological improvement. Analyses were based on propensity score overlap weighting (leading to exact balance in patient history, stroke characteristics, and initial management between groups) and confirmed with adjusted logistic regression (sensitivity analysis). A stratified analysis based on pre-established ER predictors (IVT-to-EReval time, occlusion site, and thrombus length) was conducted. RESULTS: Overall, 1865 patients were included. ER occurred in 156/787 (19.8%) and 199/1078 (18.5%) patients treated with tenecteplase or alteplase, respectively (odds ratio, 1.09 [95% CI, 0.83-1.44]; P=0.52). A differential effect of tenecteplase versus alteplase on the probability of ER according to thrombus length was observed (Pinteraction=0.003), with tenecteplase being associated with higher odds of ER in thrombi >10 mm (odds ratio, 2.43 [95% CI, 1.02-5.81]; P=0.04). There was no differential effect of tenecteplase versus alteplase on the likelihood of ER according to the IVT-to-EReval time (Pinteraction=0.40) or occlusion site (Pinteraction=0.80). CONCLUSIONS: Both thrombolytics achieved ER in one-fifth of patients with large-vessel occlusion acute ischemic stroke without significant interaction with IVT-to-EReval time and occlusion site. Compared with alteplase, tenecteplase was associated with a 2-fold higher likelihood of ER in larger thrombi.

Treatment times, functional outcome, and hemorrhage rates after switching to tenecteplase for stroke thrombolysis: Insights from the TETRIS registry.

Introduction: The encouraging efficacy and safety data on intravenous thrombolysis with tenecteplase in ischemic stroke and its practical advantages motivated our centers to switch from alteplase to tenecteplase. We report its impact on treatment times and clinical outcomes. Methods: We retrospectively analyzed clinical and procedural data of patients treated with alteplase or tenecteplase in a comprehensive (CSC) and a primary stroke center (PSC), which transitioned respectively in 2019 and 2018. Tenecteplase enabled in-imaging thrombolysis in the CSC. The main outcomes were the imaging-to-thrombolysis and thrombolysis-to-puncture times. We assessed the association of tenecteplase with 3-month functional independence and parenchymal hemorrhage (PH) with multivariable logistic models. Results: We included 795 patients, 387 (48.7%) received alteplase and 408 (51.3%) tenecteplase. Both groups (tenecteplase vs alteplase) were similar in terms of age (75 vs 76 years), baseline NIHSS score (7 vs 7.5) and proportion of patients treated with mechanical thrombectomy (24.1% vs 27.5%). Tenecteplase patients had shorter imaging-to-thrombolysis times (27 vs 36 min, p < 0.0001) mainly driven by patients treated in the CSC (22 vs 38 min, p < 0.001). In the PSC, tenecteplase patients had shorter thrombolysis-to-puncture times (84 vs 95 min, p = 0.02), reflecting faster interhospital transfer for MT. 3-month functional independence rate was higher in the tenecteplase group (62.8% vs 53.4%, p < 0.01). In the multivariable analysis, tenecteplase was significantly associated with functional independence (ORa 1.68, 95% CI 1.15-2.48, p < 0.01), but not with PH (ORa 0.68, 95% CI 0.41-1.12, p = 0.13). Conclusion: Switch from alteplase to tenecteplase reduced process times and may improve functional outcome, with similar safety profile.

Should Patients With Acute Minor Ischemic Stroke With Isolated Internal Carotid Artery Occlusion Be Thrombolysed?

BACKGROUND: We recently reported a worrying 30% rate of early neurological deterioration (END) occurring within 24 hours following intravenous thrombolysis (IVT) in minor stroke with isolated internal carotid artery occlusion (ie, without additional intracranial occlusion), mainly due to artery-to-artery embolism. Here, we hypothesize that in this setting IVT-as compared to no-IVT-may foster END, in particular by favoring artery-to-artery embolism from thrombus fragmentation. METHODS: From a large multicenter retrospective database, we compared minor stroke (National Institutes of Health Stroke Scale score <6) isolated internal carotid artery occlusion patients treated within 4.5 hours of symptoms onset with either IVT or antithrombotic therapy between 2006 and 2020 (inclusion date varied among centers). Primary outcome was END within 24 hours (≥4 National Institutes of Health Stroke Scale points increase within 24 hours), and secondary outcomes were END within 7 days (END7d) and 3-month modified Rankin Scale score 0 to 1. RESULTS: Overall, 189 patients were included (IVT=95; antithrombotics=94 [antiplatelets, n=58, anticoagulants, n=36]) from 34 centers. END within 24 hours and END7d occurred in 46 (24%) and 60 (32%) patients, respectively. Baseline clinical and radiological variables were similar between the 2 groups, except significantly higher National Institutes of Health Stroke Scale (median 3 versus 2) and shorter onset-to-imaging (124 versus 149min) in the IVT group. END within 24 hours was more frequent following IVT (33% versus 16%, adjusted hazard ratio, 2.01 [95% CI, 1.07-3.92]; P=0.03), driven by higher odds of artery-to-artery embolism (20% versus 9%, P=0.09). However, END7d and 3-month modified Rankin Scale score of 0 to 1 did not significantly differ between the 2 groups (END7d: adjusted hazard ratio, 1.29 [95% CI, 0.75-2.23]; P=0.37; modified Rankin Scale score of 0-1: adjusted odds ratio, 1.1 [95% CI, 0.6-2.2]; P=0.71). END7d occurred earlier in the IVT group: median imaging-to-END 2.6 hours (interquartile range, 1.9-10.1) versus 20.4 hours (interquartile range, 7.8-34.4), respectively, P<0.01. CONCLUSIONS: In our population of minor strokes with iICAO, although END rate at 7 days and 3-month outcome were similar between the 2 groups, END-particularly END due to artery-to-artery embolism-occurred earlier following IVT. Prospective studies are warranted to further clarify the benefit/risk profile of IVT in this population.

Cerebello-Motor Paired Associative Stimulation and Motor Recovery in Stroke: a Randomized, Sham-Controlled, Double-Blind Pilot Trial.

Cerebellum is a key structure for functional motor recovery after stroke. Enhancing the cerebello-motor pathway by paired associative stimulation (PAS) might improve upper limb function. Here, we conducted a randomized, double-blind, sham-controlled pilot trial investigating the efficacy of a 5-day treatment of cerebello-motor PAS coupled with physiotherapy for promoting upper limb motor function compared to sham stimulation. The secondary objectives were to determine in the active treated group (i) whether improvement of upper limb motor function was associated with changes in corticospinal excitability or changes in functional activity in the primary motor cortex and (ii) whether improvements were correlated to the structural integrity of the input and output pathways. To that purpose, hand dexterity and maximal grip strength were assessed along with TMS recordings and multimodal magnetic resonance imaging, before the first treatment, immediately after the last one and a month later. Twenty-seven patients were analyzed. Cerebello-motor PAS was effective compared to sham in improving hand dexterity (p: 0.04) but not grip strength. This improvement was associated with increased activation in the ipsilesional primary motor cortex (p: 0.04). Moreover, the inter-individual variability in clinical improvement was partly explained by the structural integrity of the afferent (p: 0.06) and efferent pathways (p: 0.02) engaged in this paired associative stimulation (i.e., cortico-spinal and dentato-thalamo-cortical tracts). In conclusion, cerebello-motor-paired associative stimulation combined with physiotherapy might be a promising approach to enhance upper limb motor function after stroke.Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT02284087.

Functional Outcome, Recanalization, and Hemorrhage Rates After Large Vessel Occlusion Stroke Treated With Tenecteplase Before Thrombectomy.

BACKGROUND AND OBJECTIVES: To investigate in routine care the efficacy and safety of IV thrombolysis (IVT) with tenecteplase prior to mechanical thrombectomy (MT) in patients with large vessel occlusion acute ischemic strokes (LVO-AIS), either secondarily transferred after IVT or directly admitted to a comprehensive stroke center (CSC). METHODS: We retrospectively analyzed clinical and procedural data of patients treated with 0.25 mg/kg tenecteplase within 270 minutes of LVO-AIS who underwent brain angiography. The main outcome was 3-month functional independence (modified Rankin Scale score ≤2). Recanalization (revised Treatment in Cerebral Ischemia score 2b-3) was evaluated before (pre-MT) and after MT (final). RESULTS: We included 588 patients (median age 75 years [interquartile range (IQR) 61-84]; 315 women [54%]; median NIH Stroke Scale score 16 [IQR 10-20]), of whom 520 (88%) were secondarily transferred after IVT. Functional independence occurred in 47% (n = 269/570; 95% confidence interval [CI] 43.0-51.4) of patients. Pre-MT recanalization occurred in 120 patients (20.4%; 95% CI 17.2-23.9), at a similar rate across treatment paradigms (direct admission, n = 14/68 [20.6%]; secondary transfer, n = 106/520 [20.4%]; p > 0.99) despite a shorter median IVT to puncture time in directly admitted patients (38 [IQR 23-55] vs 86 [IQR 70-110] minutes; p < 0.001). Final recanalization was achieved in 492 patients (83.7%; 95%CI 80.4-86.6). Symptomatic intracerebral hemorrhage occurred in 2.5% of patients (n = 14/567; 95% CI 1.4-4.1). DISCUSSIONS: Tenecteplase before MT is safe, effective, and achieves a fast recanalization in everyday practice in patients secondarily transferred or directly admitted to a CSC, in line with published results. These findings should encourage its wider use in bridging therapy. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence that tenecteplase within 270 minutes of LVO-AIS increases the probability of functional independence.

The wide spectrum of COVID-19 neuropsychiatric complications within a multidisciplinary centre.

A variety of neuropsychiatric complications has been described in association with COVID-19 infection. Large scale studies presenting a wider picture of these complications and their relative frequency are lacking. The objective of our study was to describe the spectrum of neurological and psychiatric complications in patients with COVID-19 seen in a multidisciplinary hospital centre over 6 months. We conducted a retrospective, observational study of all patients showing neurological or psychiatric symptoms in the context of COVID-19 seen in the medical and university neuroscience department of Assistance Publique Hopitaux de Paris-Sorbonne University. We collected demographic data, comorbidities, symptoms and severity of COVID-19 infection, neurological and psychiatric symptoms, neurological and psychiatric examination data and, when available, results from CSF analysis, MRI, EEG and EMG. A total of 249 COVID-19 patients with a de novo neurological or psychiatric manifestation were included in the database and 245 were included in the final analyses. One-hundred fourteen patients (47%) were admitted to the intensive care unit and 10 (4%) died. The most frequent neuropsychiatric complications diagnosed were encephalopathy (43%), critical illness polyneuropathy and myopathy (26%), isolated psychiatric disturbance (18%) and cerebrovascular disorders (16%). No patients showed CSF evidence of SARS-CoV-2. Encephalopathy was associated with older age and higher risk of death. Critical illness neuromyopathy was associated with an extended stay in the intensive care unit. The majority of these neuropsychiatric complications could be imputed to critical illness, intensive care and systemic inflammation, which contrasts with the paucity of more direct SARS-CoV-2-related complications or post-infection disorders.

Elucidating the Structural and Functional Correlates of Upper-Limb Poststroke Motor Impairment.

Background and Purpose- Many studies have attempted to bring to light the neural correlates of poststroke motor impairment, but few have used multimodal approach to explain it. The aim of this study was to elucidate neural structural and functional correlates of upper limb motor impairment by combining electrophysiological, anatomic, and functional neuroimaging data. Methods- Forty ischemic stroke patients (median [min-max] age: 63 [33-82] years, time poststroke: 3.5 [1.1-58] months) with unilateral upper limb weakness were included. The upper limb motor impairment was defined by a motor composite score. Simple linear analysis followed by multiple linear regression analysis were performed to identify which variables (corticospinal excitability, laterality indices within the primary motor cortex or corticospinal [CST], and corpus callosum tracts integrity) were the best explaining factors of upper limb motor impairment. Results- There was a significant correlation between the resting motor threshold ratio and CST damage (r= -0.50 [95% CI, -0.70 to -0.22]; P<0.001) as well as the motor-evoked potentials amplitude (r= -0.73 [95% CI, -0.85 to -0.54]; P<0.001). Only the resting motor threshold ratio was retained by the multiple regression model and explained half of the variance (49%; P<0.001) of the upper limb motor impairment after stroke. Conclusions- The implementation of quantitative neurophysiological measurements such as the resting motor threshold as a surrogate marker of impairment could be considered in neurorehabilitation trials.

Harmful neutrophil subsets in patients with ischemic stroke: Association with disease severity.

Objective: To better understand the functional state of circulating neutrophils in patients with ischemic stroke (IS) for planning future clinical trials. Methods: We analyzed by flow cytometry activation state of circulating neutrophils and the distribution of neutrophil peripheral subsets in 41 patients with acute IS less than 6 hours before admission and compared them with 22 age-matched healthy controls. Results: Our results demonstrated continuous basal hyperactivation of circulating neutrophils during acute IS, characterized by lower l-selectin expression and higher CD11b expression at the cell surface, increased ROS production by neutrophils, and greater circulating levels of neutrophil elastase. Neutrophil hyperactivation was associated with deregulation of the equilibrium between apoptotic and necrotic. Patients also had higher percentages than controls of the overactive senescent (CXCR4bright/CD62Ldim) neutrophil subset and increased percentage of neutrophils with a reverse transendothelial migration (CD54highCXCR1low) phenotype. Importantly, neutrophil alterations were associated with the clinical severity of the stroke, evaluated by its NIH Stroke Scale score. Conclusion: Altogether, our results indicate that during acute IS, the inflammatory properties of circulating neutrophils rise, associated with the expansion of harmful neutrophil subsets. These changes in neutrophil homeostasis, associated with disease severity, may play an instrumental role by contributing to systemic inflammation and to the blood-brain barrier breakdown. Our findings highlight new potential therapeutic approaches of stroke by rebalancing the ratio of senescent to immunosuppressive neutrophils or decreasing reverse neutrophil transmigration or both.

Mechanical Thrombectomy in Perioperative Strokes: A Case-Control Study.

BACKGROUND AND PURPOSE: Perioperative strokes (POS) are rare but serious complications for which mechanical thrombectomy could be beneficial. We aimed to compare the technical results and patients outcomes in a population of POS versus non-POS (nPOS) treated by mechanical thrombectomy. METHODS: From 2010 to 2017, 25 patients with POS (ie, acute ischemic stroke occurring during or within 30 days after a procedure) who underwent mechanical thrombectomy (POS group) were enrolled and paired with 50 consecutive patients with nPOS (control group), based on the occlusion's site, National Institute of Health Stroke Scale, and age. RESULTS: Respectively, mean age was 68.3±16.6 versus 67.2±16.6 years (P=0.70), and median National Institute of Health Stroke Scale score at admission was 20 (interquartile range, 15-25) versus 19 (interquartile range, 17-25; P=0.79). Good clinical outcome (modified Rankin Scale score of 0-2 at 3 months) was achieved by 33.3% (POS) versus 56.5% (nPOS) of patients (P=0.055). Successful reperfusion (modified Thrombolysis In Cerebral Infarction score of ≥2b) was obtained in 76% (POS) versus 86% (nPOS) of cases (P=0.22). Mortality at 3 months was 33.3% in the POS group versus 4.2% (nPOS) (P=0.002). The rate of major procedural complications was 4% (POS) versus 6% (nPOS); none were lethal. Average time from symptoms' onset to reperfusion was 4.9 hours (±2.0) in POS versus 5.2 hours (±2.6). CONCLUSIONS: Successful reperfusion seems accessible in POS within a reasonable amount of time and with a good level of safety. However, favorable outcome was achieved with a lower rate than in nPOS, owing to a higher mortality rate.

Management of intracerebral hemorrhage / Prise en charge des hémorragies intracérébrales

Management of intracerebral hemorrhage. Intracerebral hemorrhage represents a major public health problem because of its frequency and its high associated morbi-mortality. Thirty days post-hemorrhage, the mortality is evaluated at 42%. Intracerebral hemorrhage has the worst outcome of all types of stroke. In spite of 20 years of active research, the only treatment having proven its efficacy is hospitalization in a specialized unit. Clinicians will more likely to be confronted with intracerebral hemorrhage, because of the aging population and growing anticoagulation use. Each situation has its own specificities and deserves a specific aetiological work-up and care. We propose an up-to-date review of medical and surgical treatments that aim to reduce the size of heamtoma but also medical treatments that aim to reduce surrounding inflammation that contributes to the bad prognosis of intracerebral hemorrhage.

Prise en charge des hémorragies intracérébrales. L'hémorragie intracérébrale est un problème de santé publique important, du fait de sa fréquence et de sa morbimortalité élevée et précoce : à J30, la mortalité après une hémorragie intracérébrale est évaluée à 42 %.2 L'hémorragie intracérébrale est l'accident vasculaire cérébral au pronostic le plus péjoratif. Malgré une recherche thérapeutique importante ces 20 dernières années, le seul traitement ayant montré son efficacité est la prise en charge en unité de neurologie vasculaire (recommandation de classe 1).49 Le clinicien est susceptible d'être confronté aux hémorragies intracérébrales, du fait de la croissance de la population âgée et de l'utilisation plus fréquente d'anticoagulants. La prise en charge gagne à être adaptée à chaque situation, en fonction d'un diagnostic causal le plus précis possible. Nous proposons une revue actualisée des interventions thérapeutiques non spécifiques dans l'hémorragie intracérébrale : celles-ci comprennent les interventions médicales et chirurgicales ciblant une diminution de la taille de l'hématome mais également les interventions médicales visant à diminuer les phénomènes inflammatoires péri-hématiques contribuant au pronostic péjoratif des hémorragies intracérébrales.

Axial Diffusivity of the Corona Radiata at 24 Hours Post-Stroke: A New Biomarker for Motor and Global Outcome.

Fractional anisotropy (FA) is an effective marker of motor outcome at the chronic stage of stroke yet proves to be less efficient at early time points. This study aims to determine which diffusion metric in which location is the best marker of long-term stroke outcome after thrombolysis with diffusion tensor imaging (DTI) at 24 hours post-stroke. Twenty-eight thrombolyzed patients underwent DTI at 24 hours post-stroke onset. Ipsilesional and contralesional FA, mean (MD), axial (AD), and radial (RD) diffusivities values were calculated in different Regions-of-Interest (ROIs): (1) the white matter underlying the precentral gyrus (M1), (2) the corona radiata (CoRad), (3) the posterior limb of the internal capsule (PLIC) and (4) the cerebral peduncles (CP). NIHSS scores were acquired at admission, day 1, and day 7; modified Rankin Scores (mRS) at 3 months. Significant decreases were found in FA, MD, and AD of the ipsilesional CoRad and M1. MD and AD were also significantly lower in the PLIC. The ratio of ipsi and contralesional AD of the CoRad (CoRad-rAD) was the strongest diffusion parameter correlated with motor NIHSS scores on day 7 and with the mRS at 3 months. A Receiver-Operator Curve analysis yielded a model for the CoRad-rAD to predict good outcome based on upper limb NIHSS motor scores and mRS with high specificity and sensitivity. FA values were not correlated with clinical outcome. In conclusion, axial diffusivity of the CoRad from clinical DTI at 24 hours post-stroke is the most appropriate diffusion metric for quantifying stroke damage to predict outcome, suggesting the importance of early axonal damage.

Extensive basal ganglia edema caused by a traumatic carotid-cavernous fistula: a rare presentation related to a basal vein of Rosenthal anatomical variation.

The authors report a very rare presentation of traumatic carotid-cavernous fistula (CCF) with extensive edema of the basal ganglia and brainstem because of an anatomical variation of the basal vein of Rosenthal (BVR). A 45-year-old woman was admitted to the authors' institution for left hemiparesis, dysarthria, and a comatose state caused by right orbital trauma from a thin metal rod. Brain MRI showed a right CCF and vasogenic edema of the right side of the brainstem, right temporal lobe, and basal ganglia. Digital subtraction angiography confirmed a high-flow direct CCF and revealed a hypoplastic second segment of the BVR responsible for the hypertension in inferior striate veins and venous congestion. Endovascular treatment was performed on an emergency basis. One month after treatment, the patient's symptoms and MRI signal abnormalities almost totally disappeared. Basal ganglia and brainstem venous congestion may occur in traumatic CCF in cases of a hypoplastic or agenetic second segment of the BVR and may provoke emergency treatment.

Characteristics of clinical and electrophysiological pattern of Charcot-Marie-Tooth 4C.

To describe the clinical and electrophysiological features evoking CMT4C, an autosomal recessive (AR) form of Charcot-Marie-Tooth disease (CMT) due to mutations in the SH3TC2 gene, we screened the coding sequence of SH3TC2 gene in 102 unrelated patients with a demyelinating or intermediate CMT and a family history compatible with an AR transmission. We identified among this cohort 16 patients carrying two mutations in the SH3TC2 gene, but medical records finally analyzed 14 patients. We report clinical, electrophysiological, and molecular data of 14 patients (9 men, 5 women) with CMT4C. Mean age at examination was 43.6 years (median = 42.5). Among the 14 studied cases 6 had scoliosis as the presenting sign. Cranial nerve involvement affecting either the VIIIth, VIIth, XIIth or a combination of the IXth and Xth nerves was noted in 10 patients. Remarkably, 50% of the patients had proximal limb involvement at the time of examination. The hallmark of the electrophysiological study was the presence of probable conduction block and temporal dispersion. Thus the clinical and paraclinical spectrum of CMT4C can guide the clinician to perform analysis of the SH3TC2 gene.

DARPP-32, Jack of All Trades Master of Which?

DARPP-32 (PPP1R1B) was discovered as a substrate of cAMP-dependent protein kinase (PKA) enriched in dopamine-innervated brain areas. It is one of three related, PKA-regulated inhibitors of protein phosphatase-1 (PP1). These inhibitors seem to have appeared in early vertebrate ancestors, possibly Gnathostomes. DARPP-32 has additional important biochemical properties including inhibition of PKA when phosphorylated by Cdk5 and regulation by casein kinases 1 and 2. It is highly enriched in specific neuronal populations, especially striatal medium-size spiny neurons. As PP1 inhibitor DARPP-32 amplifies and/or mediates many actions of PKA at the plasma membrane and in the cytoplasm, with a broad spectrum of potential targets and functions. DARPP-32 also undergoes a continuous and tightly regulated cytonuclear shuttling. This trafficking is controlled by phosphorylation of Ser-97, which is necessary for nuclear export. When phosphorylated on Thr-34 and dephosphorylated on Ser-97, DARPP-32 can inhibit PP1 in the nucleus and modulate signaling pathways involved in the regulation of chromatin response. Recent work with multiple transgenic and knockout mutant mice has allowed the dissection of DARPP-32 function in striato-nigral and striato-pallidal neurons. It is implicated in the action of therapeutic and abused psychoactive drugs, in prefrontal cortex function, and in sexual behavior. However, the contribution of DARPP-32 in human behavior remains poorly understood. Post-mortem studies in humans suggest possible alterations of DARPP-32 levels in schizophrenia and bipolar disorder. Genetic studies have revealed a polymorphism with possible association with psychological and psychopathological traits. In addition, a short isoform of DARPP-32, t-DARPP, plays a role in cancer, indicating additional signaling properties. Thus, DARPP-32 is a non-essential but tightly regulated signaling hub molecule which may improve the general performance of the neuronal circuits in which it is expressed.