Probabilistic Decision-Making in Children With Dyslexia

Background

Neurocognitive mechanisms underlying developmental dyslexia (dD) remain poorly characterized apart from phonological and/or visual processing deficits. Assuming such deficits, the process of learning complex tasks like reading requires the learner to make decisions (i.e., word pronunciation) based on uncertain information (e.g., aberrant phonological percepts)-a cognitive process known as probabilistic decision making, which has been linked to the striatum. We investigate (1) the relationship between dD and probabilistic decision-making and (2) the association between the volume of striatal structures and probabilistic decision-making in dD and typical readers.

Methods

Twenty four children diagnosed with dD underwent a comprehensive evaluation and MRI scanning (3T). Children with dD were compared to age-matched typical readers (n = 11) on a probabilistic, risk/reward fishing task that utilized a Bayesian cognitive model with game parameters of risk propensity (γ+) and behavioral consistency (β), as well as an overall adjusted score (average number of casts, excluding forced-fail trials). Volumes of striatal structures (caudate, putamen, and nucleus accumbens) were analyzed between groups and associated with game parameters.

Results

dD was associated with greater risk propensity and decreased behavioral consistency estimates compared to typical readers. Cognitive model parameters associated with timed pseudoword reading across groups. Risk propensity related to caudate volumes, particularly in the dD group.

Conclusion

Decision-making processes differentiate dD, associate with the caudate, and may impact learning mechanisms. This study suggests the need for further research into domain-general probabilistic decision-making in dD, neurocognitive mechanisms, and targeted interventions in dD.

Report of a patient undergoing chronic responsive deep brain stimulation for Tourette syndrome: proof of concept

Deep brain stimulation (DBS) has emerged as a promising intervention for the treatment of select movement and neuropsychiatric disorders. Current DBS therapies deliver electrical stimulation continuously and are not designed to adapt to a patient's symptoms. Continuous DBS can lead to rapid battery depletion, which necessitates frequent surgery for battery replacement. Next-generation neurostimulation devices can monitor neural signals from implanted DBS leads, where stimulation can be delivered responsively, moving the field of neuromodulation away from continuous paradigms. To this end, the authors designed and chronically implemented a responsive stimulation paradigm in a patient with medically refractory Tourette syndrome. The patient underwent implantation of a responsive neurostimulator, which is capable of responsive DBS, with bilateral leads in the centromedian-parafascicular (Cm-Pf) region of the thalamus. A spectral feature in the 5- to 15-Hz band was identified as the control signal. Clinical data collected prior to and after 12 months of responsive therapy revealed improvements from baseline scores in both Modified Rush Tic Rating Scale and Yale Global Tic Severity Scale scores (64% and 48% improvement, respectively). The effectiveness of responsive stimulation (p = 0.16) was statistically identical to that of scheduled duty cycle stimulation (p = 0.33; 2-sided Wilcoxon unpaired rank-sum t-test). Overall, responsive stimulation resulted in a 63.3% improvement in the neurostimulator's projected mean battery life. Herein, to their knowledge, the authors present the first proof of concept for responsive stimulation in a patient with Tourette syndrome.

Measures of impulsivity in Parkinson's disease decrease after DBS in the setting of stable dopamine therapy

INTRODUCTION

Recent evidence suggests deep brain stimulation can alter impulse control. Our objective was to prospectively evaluate the effects of subthalamic nucleus (STN) and globus pallidus internus (GPi) deep brain stimulation on impulse control disorders (ICDs) in the setting of a conservative dopamine reduction strategy.

METHODS

Patients (n = 37) undergoing de novo, unilateral STN or GPi DBS lead implantation were evaluated pre-operatively and 6-12 months post-operatively for the presence of ICDs using the Questionnaire for Impulsivity in Parkinson's disease (QUIP) and by clinical interview.

RESULTS

Of the patients enrolled, 23 underwent electrode implantation in the globus pallidus internus and 14 were implanted in the subthalamic nucleus. Mean time to long term follow-up was 9.7 ± 2.4 months. Post-operative LEDD was not significantly lower than pre-operative LEDD (pre-op: 1238.53 ± 128.47 vs. post-op: 1178.18 ± 126.43, p = 0.2972, paired t-test). Mean QUIP scores were significantly lower at follow up compared to pre-operative baseline (1.51 ± 0.45 vs. 2.51 ± 0.58, p = 0.0447, paired t-test). Patients with ICDs pre-operatively (n = 14, 37.8%) had significant improvement in QUIP scores at follow-up (6.00 ± 0.94 vs. 2.64 ± 0.98, p = 0.0014, paired t-test). Improvement was not uniform across the cohort: 1 patient with ICD at baseline developed worsening symptoms, and 4 patients with no ICD pre-operatively developed clinically significant ICDs post-operatively.

CONCLUSION

When LEDD is relatively unchanged following STN or GPi DBS for PD, ICD symptoms tend toward improvement, although worsening and emergence of new ICDs can occur. In the setting of stable LEDD, these findings suggest that the intrinsic effects of DBS may play a significant role in altering impulsive behavior.

Thalamocortical network activity enables chronic tic detection in humans with Tourette syndrome

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by multiple motor and vocal tics. Deep brain stimulation (DBS) is an emerging therapy for severe cases of TS. We studied two patients with TS implanted with bilateral Medtronic Activa PC + S DBS devices, capable of chronic recordings, with depth leads in the thalamic centromedian-parafascicular complex (CM-PF) and subdural strips over the precentral gyrus. Low-frequency (1-10 Hz) CM-PF activity was observed during tics, as well as modulations in beta rhythms over the motor cortex. Tics were divided into three categories: long complex, complex, and simple. Long complex tics, tics involving multiple body regions and lasting longer than 5 s, were concurrent with a highly detectable thalamocortical signature (average recall [sensitivity] 88.6%, average precision 96.3%). Complex tics were detected with an average recall of 63.9% and precision of 36.6% and simple tics an average recall of 39.3% and precision of 37.9%. The detections were determined using data from both patients.

Scheduled, intermittent stimulation of the thalamus reduces tics in Tourette syndrome

INTRODUCTION

Personalized, scheduled deep brain stimulation in Tourette syndrome (TS) may permit clinically meaningful tic reduction while reducing side effects and increasing battery life. Here, we evaluate scheduled DBS applied to TS at two-year follow-up.

METHODS

Five patients underwent bilateral centromedian thalamic (CM) region DBS. A cranially contained constant-current device delivering stimulation on a scheduled duty cycle, as opposed to the standard continuous DBS paradigm was utilized. Baseline vs. 24-month outcomes were collected and analyzed, and a responder analysis was performed. A 40% improvement in the Modified Rush Tic Rating Scale (MRTRS) total score or Yale Global Tic Severity Scale (YGTSS) total score defined a full responder.

RESULTS

Three of the 4 patients followed to 24 months reached full responder criteria and had a mean stimulation time of 1.85 h per day. One patient lost to follow-up evaluated at the last time point (month 18) was a non-responder. Patients exhibited improvements in MRTRS score beyond the improvements previously reported for the 6 month endpoint; on average, MRTRS total score was 15.6% better at 24 months than at 6 months and YGTSS total score was 14.8% better. Combining the patients into a single cohort revealed significant improvements in the MRTRS total score (-7.6 [5.64]; p = 0.02).

CONCLUSION

Electrical stimulation of the centromedian thalamic region in a scheduled paradigm was effective in suppressing tics, particularly phonic tics. Full responders were able to achieve the positive DBS effect with a mean of 2.3 ± 0.9 (SEM) hours of DBS per day.

Proceedings of the Third Annual Deep Brain Stimulation Think Tank: A Review of Emerging Issues and Technologies

The proceedings of the 3rd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, imaging, and computational work on DBS for the treatment of neurological and neuropsychiatric disease. Significant innovations of the past year are emphasized. The Think Tank's contributors represent a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers, and members of industry. Presentations and discussions covered a broad range of topics, including policy and advocacy considerations for the future of DBS, connectomic approaches to DBS targeting, developments in electrophysiology and related strides toward responsive DBS systems, and recent developments in sensor and device technologies.

The Subthalamic Nucleus, Limbic Function, and Impulse Control

It has been well documented that deep brain stimulation (DBS) of the subthalamic nucleus (STN) to address some of the disabling motor symptoms of Parkinson's disease (PD) can evoke unintended effects, especially on non-motor behavior. This observation has catalyzed more than a decade of research concentrated on establishing trends and identifying potential mechanisms for these non-motor effects. While many issues remain unresolved, the collective result of many research studies and clinical observations has been a general recognition of the role of the STN in mediating limbic function. In particular, the STN has been implicated in impulse control and the related construct of valence processing. A better understanding of STN involvement in these phenomena could have important implications for treating impulse control disorders (ICDs). ICDs affect up to 40% of PD patients on dopamine agonist therapy and approximately 15% of PD patients overall. ICDs have been reported to be associated with STN DBS. In this paper we will focus on impulse control and review pre-clinical, clinical, behavioral, imaging, and electrophysiological studies pertaining to the limbic function of the STN.

Proceedings of the Second Annual Deep Brain Stimulation Think Tank: What's in the Pipeline

The proceedings of the 2nd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, and computational work on DBS for the treatment of neurological and neuropsychiatric disease and represent the insights of a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers and members of industry. Presentations and discussions covered a broad range of topics, including advocacy for DBS, improving clinical outcomes, innovations in computational models of DBS, understanding of the neurophysiology of Parkinson's disease (PD) and Tourette syndrome (TS) and evolving sensor and device technologies.

Grade migration in prostate cancer: an analysis using the Surveillance, Epidemiology, and End Results registry

To utilize the Surveillance, Epidemiology, and End Results (SEER) registry to examine trends in grade assignment. Data from 411 325 patients from 1984 to 2003 were analyzed for grade migration and for cause-specific survival (CSS) as a function of grade. There has been a significant grade migration during the study period (P<0.001), principally from well-differentiated (WD) to moderately differentiated (MD) disease. Five-year CSS of MD and WD patients have converged, suggesting a decreasing role of grade as a prognostic factor. A grade migration from WD to MD assignment has occurred, suggesting that prognostic categorizations based on grade across eras may be difficult to interpret.

'Insignificant' prostate cancer on biopsy: pathologic results from subsequent radical prostatectomy

'Insignificant' prostate cancer is defined as disease of virulence insufficient to threaten survival. In this review, which describes nine articles and two abstracts discussing almost 800 cases, we discuss the correlation of such 'insignificant' biopsy findings in the context of subsequent radical prostatectomy data. From our review, minimal disease on biopsy does not reliably predict minimal disease in the subsequent prostatectomy specimen, in terms of the size and grade of tumor, extracapsular extension or positive margins. Thus, reasoned accounting should be made of other data before undertaking a course of radiation therapy as monotherapy, particularly prostate-specific antigen kinetics and potential molecular markers.

Asymptomatic carotid stenosis and unrelated operations: should we be more aggressive?

BACKGROUND

Carotid lesions will often remain asymptomatic during the perioperative period, so prophylactic carotid endarterectomy (CEA) has not been advocated before other operations. The purpose of this study was to characterize the clinical manifestations of new neurologic symptoms occurring in patients with previously asymptomatic carotid occlusive disease who have undergone recent operations.

STUDY DESIGN

We performed a retrospective review of patients developing neurologic symptoms attributable to carotid occlusive disease after unrelated operations.

RESULTS

Eleven patients (mean age 68+/-6.4 years, 8 men, 3 women) developed new neurologic symptoms from previously asymptomatic extracranial carotid stenoses after 11 unrelated procedures. Neurologic events included hemispheric stroke (n = 10) and amaurosis fugax (n = 1). Two intraoperative strokes occurred (one mastectomy, one prostatectomy). Other events occurred a mean of 5.8+/-5 (range 1 to 16) days after aortic surgery (n = 2), infrainguinal bypass (n = 3), contralateral CEA for symptomatic disease (n = 2), incisional herniorrhaphy (n = 1), and prostate surgery (n = 1). Responsible internal carotid artery lesions were all stenoses greater than 80%; seven were clearly greater than 90%. Those suffering intraoperative stroke or stroke within 24 hours of operation (n = 3) were not receiving antithrombotic therapy. All other events (n = 8) occurred despite the use ofantiplatelet or anticoagulant agents. Four underwent emergent CEA. Four had elective CEA performed after reaching a neurological recovery plateau.

CONCLUSIONS

Critical, asymptomatic internal carotid artery stenoses may cause neurologic symptoms after unrelated surgical procedures.

Role of physical examination in detection of abdominal aortic aneurysms

BACKGROUND

Early detection of asymptomatic abdominal aortic aneurysms (AAAs) has been advocated to decrease the high mortality rate of ruptured AAAs. The purpose of this study was to document how AAAs were detected, whether AAAs not detected on physical examination (PE) were palpable, and what factors precluded detection by PE.

METHODS

Two hundred forty-three patients undergoing elective infrarenal AAA repair at a Veterans Affairs, county, or university hospital during a 10-year period were analyzed retrospectively. The method of initial detection of the AAA, size of the AAA at initial detection and before repair, and whether the AAA was palpable on preoperative PE were recorded, and the body mass index [BMI; weight in kg/(height in meters)2] was calculated. Obese patients were defined with BMI of greater than 85th percentile.

RESULTS

Only 93 (38%) patients had their AAAs initially detected by PE; the remainder (62%) were found incidentally on radiologic examinations performed for other indications. Patients with AAAs detected by PE had lower BMIs (PE, 23.7 +/- 3.6 kg/m2; incidental, 26.0 +/- 4.6 kg/m2, p < 0.001), but there was no difference in AAA size (PE, 5.8 +/- 1.6 cm; incidental, 5.5 +/- 1.9 cm, not significant). Forty-three percent of patients with AAAs detected on radiologic examination had palpable AAAs and should have been detected on PE. Overall, 55 (23%) AAAs were not palpable on preoperative PE, even when the diagnosis was known. Obese patients had only 15% of AAAs detected by PE, and only 33% were palpable.

CONCLUSIONS

AAAs are underdiagnosed by PE, especially in obese persons. More widespread abdominal examination to detect a widened aortic pulse would improve detection of AAAs.

The durability of bilateral carotid endarterectomy

To determine the natural history and durability of bilateral carotid endarterectomy (CEA), we studied 27 patients who participated in a randomized, prospective, consecutive entry trial comparing vein patch with primary CEA closure. This cohort represented 20% of the 136 patients who took part in the 4-year study. Bilateral CEAs were planned at the time of the original admission in 13 (48%), whereas 14 (52%) developed late indications for contralateral CEA a mean of 27 +/- 7 months after the initial procedure. Among the 27 patients, 15 underwent alternating methods of CEA closure. During a mean follow-up of 64 +/- 7 months, five patients had six recurrences (four unilateral, one bilateral). The type of closure did not affect the recurrence rate. All recurrences were asymptomatic and measured < 50% diameter loss by duplex criteria. There were no strokes. Two other patients had late transient ischemic attacks, but neither of them had arteriographic evidence of recurrent carotid disease. No patient underwent reoperative CEA. These data demonstrate that bilateral CEA is durable. Late recurrences are rare and clinically insignificant. The higher rate of unilateral recurrence suggests that local factors play a more important role than systemic factors in the etiology of recurrent disease.

Blunt pediatric vascular trauma: analysis of forty-one consecutive patients undergoing operative intervention

PURPOSE

The purpose of this study was to determine the contribution of blunt vascular trauma to death and disability in children.

METHODS

We reviewed the medical records of 41 patients aged 17 years and younger requiring operative intervention for 48 blunt vascular injuries during the past 18 years.

RESULTS

Eight patients had arterial injuries (seven brachial, one superficial femoral) associated with orthopedic trauma resulting from falls. All eight were associated with a pulse deficit and were easily recognized. None of the eight had late sequelae after vascular repair. Thirty-three patients had vascular trauma as a result of motor vehicle crashes (n = 17), motor vehicle/pedestrian accidents (n = 12), or severe crush injuries (n = 4). Twenty-one (64%) were admitted in shock. Twenty-one major abdominal venous injuries were present in 17 patients and were lethal in 11 (65%). Abdominal venous injuries were not recognized before laparotomy. Nine of the 33 (27%) patients had extremity vascular injuries associated with orthopedic trauma, and three (9%) had major injuries of thoracic vessels. Only three patients had major abdominal arterial injuries in this series.

CONCLUSIONS

Vascular injuries resulting from blunt trauma are rare in the pediatric age group. Whereas blunt arterial injuries associated with long bone fractures are readily recognized, easily treated, and result in minimal late morbidity, blunt abdominal venous injuries are rarely recognized before exploration and are lethal in more than half. Devastating venous injuries are more common than arterial injuries after blunt abdominal trauma in children.

Adaptation and negative aftereffect to lateral optical displacement in newly hatched chicks

Chicks wearing hoods containing 8.5-degree wedge prisms from the day of hatching showed both significant reduction in the average lateral displacement of pecking (adaptation) and significant pecking overcompensation in the direction opposite to the original displacement (negative aftereffect) when matched 0-degree plates were substituted for the prisms on the 8th day.