Outcomes among patients discharged from the emergency department with a diagnosis of peripheral vertigo

Objective

We aimed to determine the risk of short- and long-term stroke, as well as accidental injury, in patients discharged from an emergency department who were given a diagnosis of a peripheral vestibular disorder.

Methods

In this population-based, retrospective, cohort study, we identified all adult patients who were discharged from an emergency department in Ontario, Canada, between 2006 and 2011, with a primary diagnosis of a peripheral vestibular disorder. We assessed hospitalized strokes at 7, 30, 90, and 365 days, as well as subsequent falls, motor vehicle accidents, fractures, and burns. To provide context, we assessed the same outcomes in propensity score-matched discharged emergency department patients with renal colic.

Results

Among 41,794 qualifying patients, 76 (0.18%) had a stroke within 30 days. Accidental injury at 30 days ranged from 0.01% (falls) to 0.15% (fractures). The relative risk (RR) of 30-day stroke was 9.3 (95% confidence interval [CI]: 4.3-20.3) times higher than among matched renal colic controls. The RR was highest at 7 days (50.0; 95% CI, 6.9–362.0) and diminished with duration from the emergency department visit: RR 6.1 (95% CI, 3.5–10.7) at 90 days and 2.5 (95% CI, 1.8–3.5) at 1 year. There was no difference in the risk of accidental injury.

Interpretation

The frequency of early stroke after discharge from an emergency department with a diagnosis of a peripheral vestibular disorder was extremely low. However, the relative risk was markedly higher than in matched patients with renal colic, suggesting that some strokes, or sentinel events for strokes, are being misdiagnosed as peripheral vestibular disorders.

 Ann Neurol 2015

Mutations in the mammalian target of rapamycin pathway regulators NPRL2 and NPRL3 cause focal epilepsy

Objective

Focal epilepsies are the most common form observed and have not generally been considered to be genetic in origin. Recently, we identified mutations in DEPDC5 as a cause of familial focal epilepsy. In this study, we investigated whether mutations in the mammalian target of rapamycin (mTOR) regulators, NPRL2 and NPRL3, also contribute to cases of focal epilepsy.

Methods

We used targeted capture and next-generation sequencing to analyze 404 unrelated probands with focal epilepsy. We performed exome sequencing on two families with multiple members affected with focal epilepsy and linkage analysis on one of these.

Results

In our cohort of 404 unrelated focal epilepsy patients, we identified five mutations in NPRL2 and five in NPRL3. Exome sequencing analysis of two families with focal epilepsy identified NPRL2 and NPRL3 as the top candidate-causative genes. Some patients had focal epilepsy associated with brain malformations. We also identified 18 new mutations in DEPDC5.

Interpretation

We have identified NPRL2 and NPRL3 as two new focal epilepsy genes that also play a role in the mTOR-signaling pathway. Our findings show that mutations in GATOR1 complex genes are the most significant cause of familial focal epilepsy identified to date, including cases with brain malformations. It is possible that deregulation of cellular growth control plays a more important role in epilepsy than is currently recognized. 

Ann Neurol 2015

Familial cortical dysplasia caused by mutation in the mammalian target of rapamycin regulator NPRL3

We describe first cousin sibling pairs with focal epilepsy, one of each pair having focal cortical dysplasia (FCD) IIa. Linkage analysis and whole-exome sequencing identified a heterozygous germline frameshift mutation in the gene encoding nitrogen permease regulator-like 3 (NPRL3). NPRL3 is a component of GAP Activity Towards Rags 1, a negative regulator of the mammalian target of rapamycin complex 1 signaling pathway. Immunostaining of resected brain tissue demonstrated mammalian target of rapamycin activation. Screening of 52 unrelated individuals with FCD identified 2 additional patients with FCDIIa and germline NPRL3 mutations. Similar to DEPDC5, NPRL3mutations may be considered as causal variants in patients with FCD or magnetic resonance imaging–negative focal epilepsy.

 Ann Neurol 2015

Definition and Implications of the Preventable Stroke

Importance  Although patients with acute stroke are routinely evaluated for potential treatment (ie, treatability of the stroke), preventability of the presenting stroke is generally not seriously considered.

Objective  To systematically analyze stroke preventability.

Design, Setting, and Participants  We evaluated medical records of 274 consecutive patients discharged with a diagnosis of ischemic stroke between December 2, 2010, and June 11, 2012, at the University of California Irvine Medical Center. Mean (SE) patient age was 67.2 (0.8) years. Data analysis was conducted from July 3, 2014, to August 4, 2015.

Exposures  Medical records were systematically examined for demographic information, stroke risk factors, stroke severity, and acute stroke treatment.

Main Outcomes and Measures  We defined stroke preventability as the degree to which the patient’s presenting stroke was preventable. Using variables easily determined at onset of stroke, we developed a 10-point scale (0, not preventable; 10, most preventable) to classify the degree of stroke preventability. Our focus was effectiveness of treatment of hypertension (0-2 points), hyperlipidemia (0-2 points), and atrial fibrillation (0-4 points), as well as use of antithrombotic treatment for known prior cerebrovascular and cardiovascular disease (0-2 points).

Results  Total risk scores ranged from 0 to 8 (mean [SE], 2.2 [0.1]), with 207 patients (75.5%) exhibiting some degree of preventability (score of 1 or higher). Seventy-one patients (25.9%) had scores of 4 or higher, indicating that the stroke was highly preventable. Severity of stroke as determined by the National Institutes of Health Stroke Scale score was not related to preventability of stroke. However, 21 of 71 patients (29.6%) whose stroke was highly preventable were treated with intravenous or intra-arterial acute stroke therapy while these treatments were provided for only 13 of 67 patients (19.4%) with scores of 0 (no preventability) and 19 of 136 patients (14.0%) with scores of 1 to 3 (low preventability) (P = .03).

Conclusions and Relevance  Most patients with acute stroke exhibited some degree of preventability. Preventability and treatment of stroke were significantly associated, indicating that the most preventable strokes paradoxically were more likely to receive acute treatment.

JAMA Neurology 2015

Effect of alteplase on the CT hyperdense artery sign and outcome after ischemic stroke

Objective: To investigate whether the location and extent of the CT hyperdense artery sign (HAS) at presentation affects response to IV alteplase in the randomized controlled Third International Stroke Trial (IST-3).

Methods: All prerandomization and follow-up (24–48 hours) CT brain scans in IST-3 were assessed for HAS presence, location, and extent by masked raters. We assessed whether HAS grew, persisted, shrank, or disappeared at follow-up, the association with 6-month functional outcome, and effect of alteplase. IST-3 is registered (ISRCTN25765518).

Results: HAS presence (vs absence) independently predicted poor 6-month outcome (increased Oxford Handicap Scale [OHS]) on adjusted ordinal regression analysis (odds ratio [OR] 0.66, p < 0.001). Outcome was worse in patients with more (vs less) extensive HAS (OR 0.61, p = 0.027) but not in proximal (vs distal) HAS (p = 0.420). Increasing age was associated with more HAS growth at follow-up (OR 1.01, p = 0.013). Treatment with alteplase increased HAS shrinkage/disappearance at follow-up (OR 0.77, p = 0.006). There was no significant difference in HAS shrinkage with alteplase in proximal (vs distal) or more (vs less) extensive HAS (p = 0.516 and p = 0.580, respectively). There was no interaction between presence vs absence of HAS and benefit of alteplase on 6-month OHS (p = 0.167).

Conclusions: IV alteplase promotes measurable reduction in HAS regardless of HAS location or extent. Alteplase increased independence at 6 months in patients with and without HAS.

Classification of evidence: This study provides Class I evidence that for patients within 6 hours of ischemic stroke with a CT hyperdense artery sign, IV alteplase reduced intra-arterial hyperdense thrombus.

Neurology 2015

Vestibular thalamus Two distinct graviceptive pathways

Objective: To determine whether there are distinct thalamic regions statistically associated with either contraversive or ipsiversive disturbance of verticality perception measured by subjective visual vertical (SVV).

Methods: We used modern statistical lesion behavior mapping on a sample of 37 stroke patients with isolated thalamic lesions to clarify which thalamic regions are involved in graviceptive otolith processing and whether there are distinct regions associated with contraversive or ipsiversive SVV deviation.

Results: We found 2 distinct systems of graviceptive processing within the thalamus. Contraversive tilt of SVV was associated with lesions to the nuclei dorsomedialis, intralamellaris, centrales thalami, posterior thalami, ventrooralis internus, ventrointermedii, ventrocaudales and superior parts of the nuclei parafascicularis thalami. The regions associated with ipsiversive tilt of SVV were located in more inferior regions, involving structures such as the nuclei endymalis thalami, inferior parts of the nuclei parafascicularis thalami, and also small parts of the junction zone of the nuclei ruber tegmenti and brachium conjunctivum.

Conclusions: Our data indicate that there are 2 anatomically distinct graviceptive signal processing mechanisms within the vestibular network in humans that lead, when damaged, to a vestibular tone imbalance either to the contraversive or to the ipsiversive side.

Neurology 2015

A recessive Nav1.4 mutation underlies congenital myasthenic syndrome with periodic paralysis

Objective: To determine the molecular basis of a complex phenotype of congenital muscle weakness observed in an isolated but consanguineous patient.

Methods: The proband was evaluated clinically and neurophysiologically over a period of 15 years. Genetic testing of candidate genes was performed. Functional characterization of the candidate mutation was done in mammalian cell background using whole cell patch clamp technique.

Results: The proband had fatigable muscle weakness characteristic of congenital myasthenic syndrome with acute and reversible attacks of most severe muscle weakness as observed in periodic paralysis. We identified a novel homozygous SCN4A mutation (p.R1454W) linked to this recessively inherited phenotype. The p.R1454W substitution induced an important enhancement of fast and slow inactivation, a slower recovery for these inactivated states, and a frequency-dependent regulation of Na_v1.4 channels in the heterologous expression system.

Conclusion: We identified a novel loss-of-function mutation of Na_v1.4 that leads to a recessive phenotype combining clinical symptoms and signs of congenital myasthenic syndrome and periodic paralysis, probably by decreasing channel availability for muscle action potential genesis at the neuromuscular junction and propagation along the sarcolemma.

Neurology 2015