Midodrine for orthostatic hypotension and recurrent reflex syncope

Objective: Symptomatic orthostatic hypotension (SOH) and recurrent reflex syncope (RRS) can be disabling. Midodrine has been proposed in the management of patients with these conditions but its impact on patient important outcomes remains uncertain. We performed a systematic review to evaluate the efficacy and safety of midodrine in patients with SOH and RRS.

Methods: We searched multiple electronic databases without language restriction from their inception to June 2013. We included randomized controlled trials of patients with SOH or RRS that compared treatment with midodrine against a control and reported data on patient important outcomes. We graded the quality of evidence according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach.

Results: Eleven trials involving 593 patients were included in this review. Three studies addressed health-related quality of life in patients with RRS, showing improvement with midodrine: risk difference 14% (95% confidence interval [CI] −3.5 to 31.6), very low confidence. Seven studies addressed symptom improvement and provided poolable data showing improvement with midodrine in patients with SOH: risk difference 32.8% (95% CI 13.5–48), low confidence; and RRS: risk difference 63.3% (95% CI 47.6–68.2), very low confidence. Five studies reported syncope recurrence in patients with RRS showing improvement with midodrine: risk difference 37% (95% CI 20.8%–47.4%), moderate confidence. The most frequent side effects in the midodrine arm were pilomotor reactions (33.6%, risk ratio 4.58 [95% CI 2.03–10.37]).

Conclusions: Evidence warranting low/moderate confidence suggests that midodrine improves clinical important outcomes in patients with SOH and RRS.

Neurology 2014

APOE ε variants increase risk of warfarin-related intracerebral hemorrhage

Objective: We aimed to assess the effect of APOE ε variants on warfarin-related intracerebral hemorrhage (wICH), evaluated their predictive power, and tested for interaction with warfarin in causing wICH.

Methods: This was a prospective, 2-stage (discovery and replication), case-control study. wICH was classified as lobar or nonlobar based on the location of the hematoma. Controls were sampled from ambulatory clinics (discovery) and random digit dialing (replication). APOE ε variants were directly genotyped. A case-control design and logistic regression analysis were utilized to test for association between APOE ε and wICH. A case-only design and logistic regression analysis were utilized to test for interaction between APOE ε and warfarin. Receiver operating characteristic curves were implemented to evaluate predictive power.

Results: The discovery stage included 319 wICHs (44% lobar) and 355 controls. APOE ε2 was associated with lobar (odds ratio [OR] 2.46; p < 0.001) and nonlobar wICH (OR 1.67; p = 0.04), whereas ε4 was associated with lobar (OR 2.09; p < 0.001) but not nonlobar wICH (p = 0.35). The replication stage (63 wICHs and 1,030 controls) confirmed the association with ε2 (p = 0.03) and ε4 (p = 0.003) for lobar but not for nonlobar wICH (p > 0.20). Genotyping information on APOE ε variants significantly improved case/control discrimination of lobar wICH (C statistic 0.80). No statistical interaction between warfarin and APOE was found (p > 0.20).

Conclusions: APOE ε variants constitute strong risk factors for lobar wICH. APOE exerts its effect independently of warfarin, although power limitations render this absence of interaction preliminary. Evaluation of the predictive ability ofAPOE in cohort studies is warranted.

Neurology 2014

Novel DYT11 gene mutation in patients without dopaminergic deficit (SWEDD) screened for dystonia

Objective: To test the hypothesis that adult-onset primary dystonia may be the underlying etiology of tremulous patients with clinical diagnosis of Parkinson disease (PD) but without evidence of dopaminergic deficit at nigrostriatal SPECT imaging.

Methods: We retrospectively reviewed clinical and imaging data of patients with clinical diagnosis of PD assessed at our tertiary movement disorder clinic, who underwent dopamine transporter SPECT imaging consecutively between 2002 and 2011. Molecular screening for DYT1, DYT5, DYT6, DYT11, and DYT16 dystonia genes was performed in all cases who met the following criteria at the time of SPECT scan: (1) clinical diagnosis of PD; (2) normal dopamine transporter SPECT; (3) asymmetric rest tremor, with or without postural/kinetic component; (4) ≥12-month follow-up; and (5) normal brain MRI. We excluded subjects with (6) overt dystonic features, and (7) head or voice tremor.

Results: Twenty-three subjects were eligible for molecular analysis. Positive family history for tremor or PD was present in 45% of probands. We found one patient with a novel heterozygous frameshift mutation in the DYT11 gene (c.1058-1062 delCACCA/p.Gln352fsX376). Electrophysiologic study of tremor revealed that the main contributor was 5- to 6-Hz pseudo-rhythmic myoclonus, primarily involving extensor muscles. In 2 brothers, we found a missense variant in the DYT5 gene (c.334A>G; p.Thr112Ala) of uncertain pathogenicity in humans.

Conclusion: Our findings provide further support to the hypothesis that adult-onset monogenic dystonia may underlie a “PD look-alike” clinical phenotype. In addition to dystonic tremor, pseudo-rhythmic myoclonus may be mischaracterized as “rest tremor.”

Neurology 2014

Diffusion tensor imaging and neurocognition in survivors of childhood acute lymphoblastic leukaemia

Survivors of childhood acute lymphoblastic leukaemia are at risk for neurocognitive impairment, though little information is available on its association with brain integrity, particularly for survivors treated without cranial radiation therapy. This study compares neurocognitive function and brain morphology in long-term adult survivors of childhood acute lymphoblastic leukaemia treated with chemotherapy alone (n = 36) to those treated with cranial radiation therapy (n = 39) and to healthy control subjects (n = 23). Mean (standard deviation) age at evaluation was 24.9 (3.6) years for the chemotherapy group and 26.7 (3.4) years for the cranial radiation therapy group, while time since diagnosis was 15.0 (1.7) and 23.9 (3.1) years, respectively. Brain grey and white matter volume and diffusion tensor imaging was compared between survivor groups and to 23 healthy controls with a mean (standard deviation) age of 23.1 (2.6) years. Survivors treated with chemotherapy alone had higher fractional anisotropy in fibre tracts within the left (P < 0.05), but not in the right, hemisphere when compared to controls. Survivors of acute lymphoblastic leukaemia, regardless of treatment, had a lower ratio of white matter to intracranial volume in frontal and temporal lobes (P < 0.05) compared with control subjects. Survivors of acute lymphoblastic leukaemia treated with chemotherapy alone performed worse in processing speed (P <0.001), verbal selective reminding (P = 0.01), and academics (P < 0.05) compared to population norms and performed better than survivors treated with cranial radiation therapy on verbal selective reminding (P =0.02), processing speed (P = 0.05) and memory span (P = 0.009). There were significant associations between neurocognitive performance and brain imaging, particularly for frontal and temporal white and grey matter volume. Survivors of acute lymphoblastic leukaemia treated with chemotherapy alone demonstrated significant long-term differences in neurocognitive function and altered neuroanatomical integrity. These results suggest substantial region-specific white matter alterations in survivors of acute lymphoblastic leukaemia possibly resulting in restricted radial diffusion due to the compaction of neuronal fibres.

Brain 2014

The evolution of primary progressive apraxia of speech

Primary progressive apraxia of speech is a recently described neurodegenerative disorder in which patients present with an isolated apraxia of speech and show focal degeneration of superior premotor cortex. Little is known about how these individuals progress over time, making it difficult to provide prognostic estimates. Thirteen subjects with primary progressive apraxia of speech underwent two serial comprehensive clinical and neuroimaging evaluations 2.4 years apart [median age of onset = 67 years (range: 49–76), seven females]. All underwent detailed speech and language, neurological and neuropsychological assessments, and magnetic resonance imaging, diffusion tensor imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography at both baseline and follow-up. Rates of change of whole brain, ventricle, and midbrain volumes were calculated using the boundary-shift integral and atlas-based parcellation, and rates of regional grey matter atrophy were assessed using tensor-based morphometry. White matter tract degeneration was assessed on diffusion-tensor imaging at each time-point. Patterns of hypometabolism were assessed at the single subject-level. Neuroimaging findings were compared with a cohort of 20 age, gender, and scan-interval matched healthy controls. All subjects developed extrapyramidal signs. In eight subjects the apraxia of speech remained the predominant feature. In the other five there was a striking progression of symptoms that had evolved into a progressive supranuclear palsy-like syndrome; they showed a combination of severe parkinsonism, near mutism, dysphagia with choking, vertical supranuclear gaze palsy or slowing, balance difficulties with falls and urinary incontinence, and one was wheelchair bound. Rates of whole brain atrophy (1.5% per year; controls = 0.4% per year), ventricular expansion (8.0% per year; controls = 3.3% per year) and midbrain atrophy (1.5% per year; controls = 0.1% per year) were elevated (P ≤ 0.001) in all 13, compared to controls. Increased rates of brain atrophy over time were observed throughout the premotor cortex, as well as prefrontal cortex, motor cortex, basal ganglia and midbrain, while white matter tract degeneration spread into the splenium of the corpus callosum and motor cortex white matter. Hypometabolism progressed over time in almost all subjects. These findings demonstrate that some subjects with primary progressive apraxia of speech will rapidly evolve and develop a devastating progressive supranuclear palsy-like syndrome ∼ 5 years after onset, perhaps related to progressive involvement of neocortex, basal ganglia and midbrain. These findings help improve our understanding of primary progressive apraxia of speech and provide some important prognostic guidelines.

Brain 2014

Translational Research in Acute Central Nervous System Injury Lessons Learned and the Future

Importance  Research to improve outcomes from acute central nervous system (CNS) injury has progressed little, although limited examples (eg, induced hypothermia for out-of-hospital ventricular fibrillation cardiac arrest and birth asphyxia and tissue plasminogen activator for ischemic stroke) have proved that it is possible to favorably alter outcome.

Objective  To chronicle the evolution of preclinical research designed to provide therapeutic interventions for acute CNS injury.

Evidence Review  Preclinical literature cited by major clinical intervention trials was systematically assessed with respect to fulfillment of fundamental elements of experimental design in current guidelines.

Findings  Preclinical studies of acute CNS injury to date have a poor record of adhering to basic tenets of experimental design, including randomization, concealment of treatment allocation, definition of sustained robustness of therapeutic benefit, and emulation of clinical disease. Major clinical trials continue to be justified and conducted on the basis of weak preclinical evidence. Publication of preclinical research guidelines and endorsement by scientific journals have been insufficient to alter practice. Novel approaches to preclinical therapeutic development, including multicenter phase 3 trials and preclinical trial registries that document a priori experimental design and primary dependent variables, may overcome this intransigence and enhance possibility for therapeutic breakthroughs.

Conclusions and Relevance  Current knowledge of acute CNS injury dictates that therapeutic discovery and translation apply known tenets of sound experimental design and emulation of the clinical disorder targeted for therapeutic intervention. Peer-review systems must demand these qualities in proposed and published research to assess validity and potential for clinical translation.

JAMA Neurolgy 2014

Effects of the Absence of Apolipoprotein E on Lipoproteins, Neurocognitive Function, and Retinal Function

Importance  The identification of a patient with a rare form of severe dysbetalipoproteinemia allowed the study of the consequences of total absence of apolipoprotein E (apoE).

Objectives  To discover the molecular basis of this rare disorder and to determine the effects of complete absence of apoE on neurocognitive and visual function and on lipoprotein metabolism.

Design, Setting, and Participants  Whole-exome sequencing was performed on the patient’s DNA. He underwent detailed neurological and visual function testing and lipoprotein analysis. Lipoprotein analysis was also performed in the Cardiovascular Research Institute, University of California, San Francisco, on blood samples from the proband’s mother, wife, 2 daughters, and normolipidemic control participants.

Main Outcome Measures  Whole-exome sequencing, lipoprotein analysis, and neurocognitive function.

Results  The patient was homozygous for an ablative APOE frameshift mutation (c.291del, p.E97fs). No other mutations likely to contribute to the phenotype were discovered, with the possible exception of two, in ABCC2 (p.I670T) and LIPC (p.G137R). Despite complete absence of apoE, he had normal vision, exhibited normal cognitive, neurological, and retinal function, had normal findings on brain magnetic resonance imaging, and had normal cerebrospinal fluid levels of β-amyloid and tau proteins. He had no significant symptoms of cardiovascular disease except a suggestion of myocardial ischemia on treadmill testing and mild atherosclerosis noted on carotid ultrasonography. He had exceptionally high cholesterol content (760 mg/dL; to convert to millimoles per liter, multiply by 0.0259) and a high cholesterol to triglycerides ratio (1.52) in very low-density lipoproteins with elevated levels of small-diameter high-density lipoproteins, including high levels of prebeta-1 high-density lipoprotein. Intermediate-density lipoproteins, low-density lipoproteins, and very low-density lipoproteins contained elevated apoA-I and apoA-IV levels. The patient’s apoC-III and apoC-IV levels were decreased in very low-density lipoproteins. Electron microscopy revealed large lamellar particles having electron-opaque cores attached to electron-lucent zones in intermediate-density and low-density lipoproteins. Low-density lipoprotein particle diameters were distributed bimodally.

Conclusions and Relevance  Despite a profound effect on lipoprotein metabolism, detailed neurocognitive and retinal studies failed to demonstrate any defects. This suggests that functions of apoE in the brain and eye are not essential or that redundant mechanisms exist whereby its role can be fulfilled. Targeted knockdown of apoE in the central nervous system might be a therapeutic modality in neurodegenerative disorders.

JAMA Neurology 2014