Hagen B. Huttner

Dynamics of Hippocampal Neurogenesis in Adult Humans

Adult-born hippocampal neurons are important for cognitive plasticity in rodents. There is evidence for hippocampal neurogenesis in adult humans, although whether its extent is sufficient to have functional significance has been questioned. We have assessed the generation of hippocampal cells in humans by measuring the concentration of nuclear-bomb-test-derived ¹⁴C in genomic DNA, and we present an integrated model of the cell turnover dynamics. We found that a large subpopulation of hippocampal neurons constituting one-third of the neurons is subject to exchange. In adult humans, 700 new neurons are added in each hippocampus per day, corresponding to an annual turnover of 1.75% of the neurons within the renewing fraction, with a modest decline during aging. We conclude that neurons are generated throughout adulthood and that the rates are comparable in middle-aged humans and mice, suggesting that adult hippocampal neurogenesis may contribute to human brain function.

Hematoma Growth and Outcome in Treated Neurocritical Care Patients With Intracerebral Hemorrhage Related to Oral Anticoagulant Therapy Comparison of Acute Treatment Strategies Using Vitamin K, Fresh Frozen Plasma, and Prothrombin Complex Concentrates

Background and Purpose— Intracerebral hemorrhage (ICH) is the most serious and potentially fatal complication of oral anticoagulant therapy (OAT). Still, there are no universally accepted treatment regimens for patients with OAT-ICH, and randomized controlled trials do not exist. The aim of the present study was to compare the acute treatment strategies of OAT-associated ICH using vitamin K (VAK), fresh frozen plasma (FFP), and prothrombin complex concentrates (PCCs) with regard to hematoma growth and outcome. Methods— In this retrospective study, a total of 55 treated patients were analyzed. Three groups were compared by reviewing the clinical, laboratory, and neuroradiological parameters: (1) patients who received PCCs alone or in combination with FFP or VAK (n=31), (2) patients treated with FFP alone or in combination with VAK (n=18), and (3) patients who received VAK as a monotherapy (n=6). The end points of early hematoma growth and outcome after 12 months were analyzed including multivariate analysis. Results— Hematoma growth within 24 hours occurred in 27% of patients. Incidence and extent of hematoma growth were significantly lower in patients receiving PCCs (19%/44%) compared with FFP (33%/54%) and VAK (50%/59%). However, this effect was no longer seen between PCC- and FFP-treated patients if international normalized ratio (INR) was completely reversed within 2 hours after admission. The overall outcome was poor (modified Rankin scale 4 to 6 in 77%). Predictors for hematoma growth were an increased INR after 2 hours, whereas administration of PCCs was significantly protective in multivariate analyses. Predictors for a poor outcome were age, baseline hematoma volume, and occurrence of hematoma growth. Conclusions— Overall, PCC was associated with a reduced incidence and extent of hematoma growth compared with FFP and VAK. This effect seems to be related to a more rapid INR reversal. Randomized controlled trials are needed to identify the most effective acute treatment regimen for lasting INR reversal because increased levels of INR were predisposing for hematoma enlargement.

MRI versus CT-based thrombolysis treatment within and beyond the 3 h time window after stroke onset: a cohort study

BACKGROUND Thrombolytic treatment with recombinant tissue plasminogen activator (rtPA) is approved for use within 3 h after stroke onset. Thus only a small percentage of patients can benefit. Meta-analyses and more recent studies suggest a benefit for a subset of patients beyond 3 h. We assessed the safety and efficacy of an MRI-based selection protocol for stroke treatment within and beyond 3 h compared with standard CT-based treatment. METHODS We assessed clinical outcome and incidence of symptomatic intracerebral haemorrhage (ICH) in 400 consecutive patients treated with intravenous rtPA. Patients eligible for thrombolysis within 3 h were selected by CT or MRI and beyond 3 h only by MRI. 18 patients were excluded from analysis because of violation of that algorithm. The remaining 382 patients were divided into three groups: CT-based treatment within 3 h (n=209); MRI-based treatment within 3 h (n=103); and MRI-based treatment beyond 3 h (n=70). FINDINGS Patients in group 3 (MRI > 3 h) had a similar 90 day outcome to those in the other two groups (48% were independent in the CT < or = 3 h group, 51% in the MRI < or = 3 h group, and 56% in group 3), but without an increased risk for symptomatic ICH (9%, 1%, 6%) or mortality (21%, 13%, 11%). MRI-selected patients overall had a significantly lower risk than CT-selected patients for symptomatic ICH (3% vs 9%; p=0.013) and mortality (12% vs 21%; p=0.021). Time to treatment did not affect outcomes in univariate and multivariate analyses. INTERPRETATION Our data suggest that beyond 3 h and maybe even within 3 h, patient selection is more important than time to treatment for a good outcome. Furthermore, MRI-based thrombolysis, irrespective of the time window, shows an improved safety profile while being at least as effective as standard CT-based treatment within 3 h.

Anticoagulant Reversal, Blood Pressure Levels, and Anticoagulant Resumption in Patients With Anticoagulation-Related Intracerebral Hemorrhage

IMPORTANCE Although use of oral anticoagulants (OACs) is increasing, there is a substantial lack of data on how to treat OAC-associated intracerebral hemorrhage (ICH). OBJECTIVE To assess the association of anticoagulation reversal and blood pressure (BP) with hematoma enlargement and the effects of OAC resumption. DESIGN, SETTING, AND PARTICIPANTS Retrospective cohort study at 19 German tertiary care centers (2006-2012) including 1176 individuals for analysis of long-term functional outcome, 853 for analysis of hematoma enlargement, and 719 for analysis of OAC resumption. EXPOSURES Reversal of anticoagulation during acute phase, systolic BP at 4 hours, and reinitiation of OAC for long-term treatment. MAIN OUTCOMES AND MEASURES Frequency of hematoma enlargement in relation to international normalized ratio (INR) and BP. Incidence analysis of ischemic and hemorrhagic events with or without OAC resumption. Factors associated with favorable (modified Rankin Scale score, 0-3) vs unfavorable functional outcome. RESULTS Hemorrhage enlargement occurred in 307 of 853 patients (36.0%). Reduced rates of hematoma enlargement were associated with reversal of INR levels <1.3 within 4 hours after admission (43/217 [19.8%]) vs INR of ≥1.3 (264/636 [41.5%]; P < .001) and systolic BP <160 mm Hg at 4 hours (167/504 [33.1%]) vs ≥160 mm Hg (98/187 [52.4%]; P < .001). The combination of INR reversal <1.3 within 4 hours and systolic BP of <160 mm Hg at 4 hours was associated with lower rates of hematoma enlargement (35/193 [18.1%] vs 220/498 [44.2%] not achieving these values; OR, 0.28; 95% CI, 0.19-0.42; P < .001) and lower rates of in-hospital mortality (26/193 [13.5%] vs 103/498 [20.7%]; OR, 0.60; 95% CI, 0.37-0.95; P = .03). OAC was resumed in 172 of 719 survivors (23.9%). OAC resumption showed fewer ischemic complications (OAC: 9/172 [5.2%] vs no OAC: 82/547 [15.0%]; P < .001) and not significantly different hemorrhagic complications (OAC: 14/172 [8.1%] vs no OAC: 36/547 [6.6%]; P = .48). Propensity-matched survival analysis in patients with atrial fibrillation who restarted OAC showed a decreased HR of 0.258 (95% CI, 0.125-0.534; P < .001) for long-term mortality. Functional long-term outcome was unfavorable in 786 of 1083 patients (72.6%). CONCLUSIONS AND RELEVANCE Among patients with OAC-associated ICH, reversal of INR <1.3 within 4 hours and systolic BP <160 mm Hg at 4 hours were associated with lower rates of hematoma enlargement, and resumption of OAC therapy was associated with lower risk of ischemic events. These findings require replication and assessment in prospective studies. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01829581.

The synthetic cannabinoid Spice as a trigger for an acute exacerbation of cannabis induced recurrent psychotic episodes

It is established that cannabis consumption cannot only trigger transient psychotic episodes but also predisposes for the development of lasting paranoid schizophrenia in a dose dependent manner (Moore et al., 2007; Muller-Vahl and Emrich, 2008). Patients with a positive family history are at a higher risk for such drug induced schizophrenic disorders (Fergusson et al., 2006; Morgan and Curran, 2008). Crossreactions between different drugs to trigger recurrence of schizophrenic episodes are rare (Huffman et al., 2008). We present the case of a 25 year old man who had a history of cannabis induced recurrent psychotic episodes and an acute reactivation of symptoms after abuse of the synthetic cannabinoid “Spice”.

Low proliferation and differentiation capacities of adult hippocampal stem cells correlate with memory dysfunction in humans

The hippocampal dentate gyrus maintains its capacity to generate new neurons throughout life. In animal models, hippocampal neurogenesis is increased by cognitive tasks, and experimental ablation of neurogenesis disrupts specific modalities of learning and memory. In humans, the impact of neurogenesis on cognition remains unclear. Here, we assessed the neurogenic potential in the human hippocampal dentate gyrus by isolating adult human neural stem cells from 23 surgical en bloc hippocampus resections. After proliferation of the progenitor cell pool in vitro we identified two distinct patterns. Adult human neural stem cells with a high proliferation capacity were obtained in 11 patients. Most of the cells in the high proliferation capacity cultures were capable of neuronal differentiation (53 ± 13% of in vitro cell population). A low proliferation capacity was observed in 12 specimens, and only few cells differentiated into neurons (4 ± 2%). This was reflected by reduced numbers of proliferating cells in vivo as well as granule cells immunoreactive for doublecortin, brain-derived neurotrophic factor and cyclin-dependent kinase 5 in the low proliferation capacity group. High and low proliferation capacity groups differed dramatically in declarative memory tasks. Patients with high proliferation capacity stem cells had a normal memory performance prior to epilepsy surgery, while patients with low proliferation capacity stem cells showed severe learning and memory impairment. Histopathological examination revealed a highly significant correlation between granule cell loss in the dentate gyrus and the same patients regenerative capacity in vitro (r = 0.813; P < 0.001; linear regression: R²(adjusted) = 0.635), as well as the same patients ability to store and recall new memories (r = 0.966; P = 0.001; linear regression: R²(adjusted) = 0.9). Our results suggest that encoding new memories is related to the regenerative capacity of the hippocampus in the human brain.

Malignant middle cerebral artery infarction: clinical characteristics, treatment strategies, and future perspectives

Space-occupying, malignant middle cerebral artery (MCA) infarctions are still one of the most devastating forms of ischaemic stroke, with a mortality of up to 80% in untreated patients. An early diagnosis is essential and depends on CT and MRI to aid the prediction of a malignant course. Several pharmacological strategies have been proposed but the efficacy of these approaches has not been supported by adequate evidence from clinical trials and, until recently, treatment of malignant MCA infarctions has been a major unmet need. Over the past 3 years, results from randomised controlled trials and their pooled analyses have provided evidence that an early hemicraniectomy leads to a substantial decrease in mortality at 6 and 12 months and is likely to improve functional outcome. Hemicraniectomy is now in routine use for the clinical management of malignant MCA infarction in patients younger than 60 years of age. However, there are still important questions about the individual indication for decompressive surgery, particularly with regard to the ideal timing of hemicraniectomy, a potential cut-off age for the procedure, the hemisphere affected, and ethical considerations about functional outcome in surviving patients.

Therapy of Acute Basilar Artery Occlusion Intraarterial Thrombolysis Alone vs Bridging Therapy

Background and Purpose— While intravenous recombinant tissue plasminogen activator (rt-PA) has been approved for acute stroke therapy within 3 hours, the optimum management of basilar artery occlusion (BAO) is still a matter of debate. We compared intraarterial thrombolysis with the combined bridging approach of intravenous abciximab and intraarterial thrombolysis with rt-PA (bridging therapy) in an observational, longitudinal, monocenter study. Methods— Between 1998 and 2006, information for 106 patients with acute BAO were prospectively entered into a local database. Patients eligible for treatment received either intraarterial thrombolysis with rt-PA alone (intraarterial thrombolysis) or were treated with intravenous abciximab and intraarterial rt-PA (bridging therapy). Outcome parameters were recanalization of the basilar artery according to Trial in Myocardial Infarction criteria, survival, and reduction of severe disability and death at 3 months. Logistic regression was used to identify independent predictors for recanalization, survival, and clinical outcome. Results— Of a total of 106 patients with confirmed BAO, 87 patients underwent subsequent angiography. Among those, 75 patients were identified who received the full treatment protocol. Patients in the bridging group had a better recanalization rate (83.7% vs 62.5%; P=0.03), a higher survival rate (58.1% vs 25%; P=0.01), and a better chance for an outcome with no or only mild to moderate disability (modified Rankin Scale score, 0-3; 34.9% vs 12.5%; P=0.02). Symptomatic intracerebral hemorrhage rates were comparable in both groups (14% in the bridging group vs 18.8%; P=0.41). Independent predictors for recanalization were age (OR, 0.95; 95% CI, 0.91-0.99), atrial fibrillation (OR, 6.53; 95% CI, 1.14-37.49), and bridging therapy (OR, 3.37; 95% CI, 1.02 to 11.18). Independent prognostic factors for outcome were Glasgow coma scale score at presentation (OR, 1.24; 95% CI, 1.03-1.45) and the combination of bridging therapy with successful recanalization (OR, 3.744; 95% CI, 1.04-13.43). Conclusion— Bridging therapy for acute BAO with intravenous abciximab and intraarterial rt-PA appears to be safe and yields higher recanalization and improved survival rates, as well as an overall improved chance for a better outcome.

Intraventricular Fibrinolysis and Lumbar Drainage for Ventricular Hemorrhage

Background and Purpose— Both intraventricular fibrinolysis (IVF) and lumbar drainage (LD) may reduce the need for exchange of external ventricular drainage (EVD) and shunt surgery in patients with intracerebral hemorrhage and severe intraventricular hemorrhage. We investigated the feasibility and safety of IVF followed by early LD for the treatment of posthemorrhagic hydrocephalus. Methods— This prospective study included patients with spontaneous ganglionic intracerebral hemorrhage and severe intraventricular hemorrhage with acute obstructive posthemorrhagic hydrocephalus who received an EVD (n=32). The treatment algorithm started with IVF (4 mg recombinant tissue plasminogen activator every 12 hours) until clearance of the third and fourth ventricles from blood. Thereupon, EVD was clamped and if clamping was unsuccessful, communicating posthemorrhagic hydrocephalus was assumed and LD placed. EVD was removed if there was neither an increase of intracranial pressure nor ventricle enlargement on CT. A ventriculoperitoneal shunt was indicated if “LD weaning” was unsuccessful for >10 days. Outcome was assessed at 90 and 180 days using the modified Rankin Scale. Results— IVF resulted in fast clearance of the third and fourth ventricles (73±50 hours). However, early EVD removal was only possible in 4 patients. The remaining 28 patients developed communicating posthemorrhagic hydrocephalus. In all of these patients, early LD was capable to replace EVD. EVD exchange was not necessary and EVD duration was 105±59 hours. Only one patient required a ventriculoperitoneal shunt. At 180 days, 20 (62.5%) patients had a good (modified Rankin Scale 0 to 3) outcome and 5 (15.6%) patients had died. One patient had asymptomatic ventricular rebleeding. Conclusions— In patients with secondary intraventricular hemorrhage and posthemorrhagic hydrocephalus, the combined treatment approach of IVF and early LD is safe and feasible, avoids EVD exchange, and may markedly reduce the need for shunt surgery.

Avoiding in hospital delays and eliminating the three-hour effect in thrombolysis for stroke

Background Intravenous thrombolysis for acute stroke is more efficient the earlier the treatment is initiated. In-hospital delays account for a significant proportion of avoidable time loss before treatment is initiated. Paradoxically, studies have reported longer door-to-needle times the earlier the patients arrive (‘three-hour effect’). Hypothesis We hypothesized that a standardized thrombolysis procedure carried out in a specialized neurological emergency room can minimize in-hospital delays and erase the ‘three-hour effect’. Methods Onset-to-door and door-to-needle times of 246 consecutive thrombolysis patients were analyzed. A standardized protocol designed to minimize in-hospital delays was tested using a resident-based stroke team within a neurological emergency room. Correlation of onset-to-door and door-to-needle times was measured as well as differences in treatment times for daytime versus night hours and weekend vs. weekday. Outcome, rate of symptomatic intracranial hemorrhage and mortality were compared with the results of SITS-MOST. Results Median door-to-needle time was 25 min compared with a mean of 68 min in SITS-MOST. door-to-needle time did not correlate with onset-to-door time (Pearsons r=−0·097; P=0·13) and patients arriving within 90 min from symptom onset showed comparable door-to-needle times with patients arriving within 90–180 min. Neither treatment on weekends nor during night hours led to significant in-hospital treatment delays. Outcome and safety parameters were comparable with those observed in SITS-MOST. Conclusions By applying a standardized and diligently monitored thrombolysis protocol, carried out by a specialized stroke team within a neurological emergency room, in-hospital delays can be minimized. This allows improvement of door-to-needle times irrespective of the time to arrival and treatment during off-hours.