Sarah K. B. Bick

Neuromodulation for restoring memory

Disorders of learning and memory have a large social and economic impact in todays society. Unfortunately, existing medical treatments have shown limited clinical efficacy or potential for modification of the disease course. Deep brain stimulation is a successful treatment for movement disorders and has shown promise in a variety of other diseases including psychiatric disorders. The authors review the potential of neuromodulation for the treatment of disorders of learning and memory. They briefly discuss learning circuitry and its involvement in Alzheimer disease and traumatic brain injury. They then review the literature supporting various targets for neuromodulation to improve memory in animals and humans. Multiple targets including entorhinal cortex, fornix, nucleus basalis of Meynert, basal ganglia, and pedunculopontine nucleus have shown a promising potential for improving dysfunctional memory by mechanisms such as altering firing patterns in neuronal networks underlying memory and increasing synaptic plasticity and neurogenesis. Significant work remains to be done to translate these findings into durable clinical therapies.

Anterior Temporal Lobectomy for Refractory Status Epilepticus in Herpes Simplex Encephalitis.

BackgroundHerpes simplex virus (HSV) is a common cause of viral encephalitis that can lead to refractory seizures. The primary treatment of HSV encephalitis is with acyclovir; however, surgery sometimes plays a role in obtaining tissue diagnosis or decompression in cases with severe mass effect. We report a unique case in which anterior temporal lobectomy was successfully used to treat refractory status epilepticus in HSV encephalitis.MethodsCase report and review of the literature.ResultsWe report a case of a 60-year-old man with HSV encephalitis, who presented with seizures originating from the right temporal lobe refractory to maximal medical management. Right anterior temporal lobectomy was performed for the purpose of treatment of refractory status epilepticus and obtaining tissue diagnosis, with ultimate resolution of seizures and excellent functional outcome.ConclusionsWe suggest that anterior temporal lobectomy should be considered in cases of HSV encephalitis with refractory status epilepticus with clear unilateral origin.

Surgical Treatment of Trigeminal Neuralgia

Trigeminal neuralgia is characterized by severe, episodic pain in the trigeminal nerve distribution. Medical therapy is the first line treatment. For patients with refractory pain, a variety of procedures including microvascular decompression, percutaneous radiofrequency rhizotomy, percutaneous glycerol rhizotomy, percutaneous balloon compression, and stereotactic radiosurgery are available. We review the literature and suggest that microvascular decompression remains the gold standard operative therapy. For patients with recurrent pain or who are poor operative candidates, percutaneous radiofrequency rhizotomy offers the best pain response rates and has the advantage of being able to selectively target affected trigeminal divisions.

Subthalamic Nucleus Deep Brain Stimulation Alters Prefrontal Correlates of Emotion Induction

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor symptoms in advanced Parkinsons disease. STN DBS may also affect emotion, possibly by impacting a parallel limbic cortico‐striatal circuit. The objective of this study was to investigate changes in prefrontal cortical activity related to DBS during an emotion induction task.

192 Older Patients Have Greater Improvements in Pain Score Following Microvascular Decompression.

INTRODUCTION Trigeminal neuralgia (TN) is more common in elderly patients, and recent studies have demonstrated safety of microvascular decompression (MVD) in this patient population. To date, age has not been shown correlated with efficacy of MVD. We evaluated the role of age in predicting outcome after MVD in patients with typical TN. METHODS We reviewed the records of patients who underwent MVD between January 1, 2004 and December 31, 2013. Patients with typical TN and demonstrated neurovascular compression on preoperative imaging were identified and contacted to obtain information about long-term pain control using the 5-point Barrow Neurological Institute (BNI) TN pain intensity score. We divided patients into 2 groups for analysis, >age 60 and <age 60. Other variables collected included sex, type of vascular compression, side of surgery, duration of symptoms, previous procedures, preoperative trigger points, preoperative medication responsiveness, pain distribution, and presence of hypertension. RESULTS The study included 124 patients, 82 under age 60 and 42 over age 60. Average follow-up was 33.8 months and was not significantly different between groups. The <60 group had average decrease in pain score of 1.9, whereas the >60 group had a decrease of 2.5 (P = .015, Mann-Whitney U test). Of patients <60, 49% had pain score of 1 or 2 (no pain, not on medications, or occasional pain, not on medications) at most recent follow-up, while 79% of patients >60 had a score of 1 or 2 (P < .001, χ test). Multivariate regression analysis was performed and found that older age and male sex were associated with better pain score after MVD (P = .017 and P = .001, respectively), whereas V2 distribution pain was associated with worse outcome (P = .001). None of the other variables were significantly correlated with outcome. CONCLUSION Patients aged 60 and older had better outcomes after MVD than younger patients. These results may help to guide future patient selection.

Intermittent subthalamic nucleus deep brain stimulation induces risk-aversive behavior in human subjects

The subthalamic nucleus (STN) is a small almond-shaped subcortical structure classically known for its role in motor inhibition through the indirect pathway within the basal ganglia. Little is known about the role of the STN in mediating cognitive functions in humans. Here, we explore the role of the STN in human subjects making decisions under conditions of uncertainty using single-neuron recordings and intermittent deep brain stimulation (DBS) during a financial decision-making task. Intraoperative single-neuronal data from the STN reveals that on high-uncertainty trials, spiking activity encodes the upcoming decision within a brief (500 ms) temporal window during the choice period, prior to the manifestation of the choice. Application of intermittent DBS selectively prior to the choice period alters decisions and biases subject behavior towards conservative wagers.

Older Patients Have Better Pain Outcomes Following Microvascular Decompression for Trigeminal Neuralgia

BACKGROUND Trigeminal neuralgia (TN) increases in prevalence with age. Although microvascular decompression (MVD) is the most effective long-term operative treatment for TN, its use in older patient populations has been debated due to its invasive nature. Recent studies have demonstrated safety of MVD in older patients; however, efficacy data are more limited. OBJECTIVE To determine the relationship between age and pain outcomes following MVD for TN. METHODS Subjects underwent MVD for TN at our institution between 1/1/2004 and 12/31/2013, had typical TN, and demonstrated neurovascular compression on preoperative imaging. We performed a retrospective case series study by reviewing the electronic medical records and performing phone interviews to determine long-term outcomes. We divided patients into 2 groups for analysis, under 60 and 60 yr of age and older. RESULTS One hundred twenty-four subjects were included in the study, 82 under 60, and 42 60 yr of age and older. The average length of follow-up was 42.4 mo. Patients in the older age group had average pain score of 1.57 at most recent follow-up, while for the younger age group it was 2.18 (P = .0084). Multiple regression analysis found that older age, male gender, and preoperative medication responsiveness were significantly correlated with lower long-term pain scores, while V2 dermatome involvement was correlated with higher long-term pain scores. CONCLUSION Patients 60 yr of age and older have significantly better long-term pain outcomes following MVD than younger patients.

Acute lymphocytic leukemia presenting as a single brain mass

Hematologic malignancies most commonly spread to the central nervous system via leptomeningeal infiltration. We present a unique case of a woman who presented with a right parietal mass as the initial manifestation of B cell acute lymphocytic leukemia. Because the diagnosis was unclear at the time of presentation she underwent surgical debulking of the mass prior to treatment with chemotherapy. Unfortunately, she relapsed several months after treatment and ultimately entered hospice care. We review the literature surrounding management considerations in patients with intracranial leukemic involvement.