Michael Y. Oh

A survey of ventriculostomy and intracranial pressure monitor placement practices.

BACKGROUND Over the past 3 decades, the incidence of ICP monitoring has consistently increased and the indications for placement have expanded. Although ventriculostomy and ICP monitor placement are among the most commonly performed neurosurgical procedures, few studies have examined the current practice patterns of these procedures. METHODS A 10-question survey was sent to 3100 practicing neurosurgeons and a similar 11-question survey to 720 neurosurgery residents. Basic demographic information and estimated rates of proper ventriculostomy placement were sought. RESULTS Nine hundred thirty-four practicing neurosurgeons and 100 neurosurgery residents responded to our survey. Respondents estimated a mean of 1.4 passes per ventriculostomy procedure for practicing neurosurgeons, 1.4 for senior residents, and 2.4 for junior residents. Estimated rate of successful cannulation of the ipsilateral ventricle ranged from 72% to 84% for these groups. CONCLUSIONS This survey gives a sketch of the current state of practice and the attitudes of practitioners toward the placement procedure. Both residents and practicing neurosurgeons admit to frequently using multiple passes and frequent catheter placement outside the ipsilateral frontal horn. Despite these imperfections, survey respondents were reluctant to embrace technology that could improve placement accuracy if it increased procedure time. Intracranial pressure monitor placement is an ideal topic for prospective study. The prevalence of the procedure would allow the morbidity associated with various monitors and emerging technologies to be quickly and accurately established. Results of such study could be applied to the tens of thousands of patients undergoing these procedures annually.

The history of external ventricular drainage

External ventricular drainage (EVD) is one of the most commonly performed neurosurgical procedures. It was first performed as early as 1744 by Claude-Nicholas Le Cat. Since then, there have been numerous changes in technique, materials used, indications for the procedure, and safety. The history of EVD is best appreciated in 4 eras of progress: development of the technique (1850-1908), technological advancements (1927-1950), expansion of indications (1960-1995), and accuracy, training, and infection control (1995-present). While EVD was first attempted in the 18th century, it was not until 1890 that the first thorough report of EVD technique and outcomes was published by William Williams Keen. He was followed by H. Tillmanns, who described the technique that would be used for many years. Following this, many improvements were made to the EVD apparatus itself, including the addition of manometry by Adson and Lillie in 1927, and continued experimentation in cannulation/drainage materials. Technological advancements allowed a great expansion of indications for EVD, sparked by Nils Lundberg, who published a thorough analysis of the use of intracranial pressure (ICP) monitoring in patients with brain tumors in 1960. This led to the application of EVD and ICP monitoring in subarachnoid hemorrhage, Reye syndrome, and traumatic brain injury. Recent research in EVD has focused on improving the overall safety of the procedure, which has included the development of guidance-based systems, virtual reality simulators for trainees, and antibiotic-impregnated catheters.

Expanding applications of deep brain stimulation: a potential therapeutic role in obesity and addiction management

BackgroundThe indications for deep brain stimulation (DBS) are expanding, and the feasibility and efficacy of this surgical procedure in various neurologic and neuropsychiatric disorders continue to be tested. This review attempts to provide background and rationale for applying this therapeutic option to obesity and addiction. We review neural targets currently under clinical investigation for DBS—the hypothalamus and nucleus accumbens—in conditions such as cluster headache and obsessive-compulsive disorder. These brain regions have also been strongly implicated in obesity and addiction. These disorders are frequently refractory, with very high rates of weight regain or relapse, respectively, despite the best available treatments.MethodsWe performed a structured literature review of the animal studies of DBS, which revealed attenuation of food intake, increased metabolism, or decreased drug seeking. We also review the available radiologic evidence in humans, implicating the hypothalamus and nucleus in obesity and addiction.ResultsThe available evidence of the promise of DBS in these conditions combined with significant medical need, support pursuing pilot studies and clinical trials of DBS in order to decrease the risk of dietary and drug relapse.ConclusionsWell-designed pilot studies and clinical trials enrolling carefully selected patients with obesity or addiction should be initiated.

Deep brain stimulation for obesity—from theoretical foundations to designing the first human pilot study

Obesity is perhaps an evolutionary consequence of a species reared with intermittent caloric reward. Humans are hardwired to enjoy food, and our bodies voraciously extract and store energy from food as if each meal was the last. As an amalgam of behavioral and metabolic disturbance, obesity is an attractive target for deep brain stimulation (DBS) since neuromodulation may be able to influence both eating behavior and metabolism. The current pandemic proportions of obesity combined with the failures and morbidity of modern treatments remain the impetus behind the application of DBS to this complex disease. We review the rationale and scientific foundations for obesity DBS and explain how this preclinical evidence has helped sculpt the design of the first human pilot study.

Mapping of microstimulation evoked responses and unit activity patterns in the lateral hypothalamic area recorded in awake humans. Technical note.

Major contributions to the understanding of human brain function have come from detailed clinical reports of responses evoked by electrical stimulation and specific brain regions during neurosurgical procedures in awake humans. In this study, microstimulation evoked responses and extracellular unit recordings were obtained intraoperatively in 3 awake patients undergoing bilateral implantation of deep brain stimulation electrodes in the lateral hypothalamus. The microstimulation evoked responses exhibited a clear anatomical distribution. Anxiety was most reliably evoked by stimulation directed ventromedially within or adjacent to the ventromedial nucleus of the hypothalamus, nausea was most reliably evoked by stimulation directed at the center of the lateral hypothalamus, and paresthesias were most reliably evoked by stimulation at the border of the lateral hypothalamus and basal nuclei. Regarding the unit recordings, the firing rates of individual neurons did not have an anatomical distribution, but a small subpopulation of neurons located at the border of the lateral hypothalamus and basal nuclei exhibited a fast rhythmically bursting behavior with an intraburst frequency of 200-400 Hz and an interburst frequency of 10-20 Hz. Based on animal studies, the lateral hypothalamic area and surrounding hypothalamic nuclei are putatively involved with a variety of physiological, behavioral, and sensory functions. The lateral hypothalamus is situated to play a dynamic and complex role in human behavior and this report further shows that to be true. In addition, this report should serve as a valuable resource for future intracranial work in which accurate targeting within this region is required.

Deep Brain Stimulation for Psychiatric Diseases: A Pooled Analysis of Published Studies Employing Disease-Specific Standardized Outcome Scales

Background: Deep brain stimulation (DBS) has emerged in recent years as a novel therapy in the treatment of refractory psychiatric disease, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and Tourettes syndrome (TS). Standardized outcome scales were crucial in establishing that DBS was an effective therapy for movement disorders. Objective: In order to better characterize the evidence supporting DBS for various psychiatric diseases, we performed a pooled analysis of those studies which incorporated specific standardized rating scales. Methods: A Medline search was conducted to identify all studies reporting DBS for MDD, OCD, and TS. The search yielded a total of 49 articles, of which 24 were included: 4 related to MDD (n = 48), 10 to OCD (n = 64), and 10 to TS (n = 46). Results: A meta-analysis of DBS for MDD, OCD, and TS in studies employing disease-specific standardized outcome scales showed that the outcome scales all improved in a statistically significant fashion for these psychiatric diseases. Our pooled analysis suggests that DBS for TS has the highest efficacy amongst the psychiatric diseases currently being treated with DBS, followed by OCD and MDD. Conclusion: DBS for psychiatric diseases remains investigational; however, even when studies failing to incorporate standardized outcome scales are excluded, there is statistically significant evidence that DBS can improve symptoms in MDD, OCD, and TS. Standardized disease-specific outcome scales facilitate pooled analysis and should be a required metric in future studies of DBS for psychiatric disease.

Deep brain stimulation for obesity: past, present, and future targets.

The authors review the history of deep brain stimulation (DBS) in patients for treating obesity, describe current DBS targets in the brain, and discuss potential DBS targets and nontraditional stimulation parameters that may improve the effectiveness of DBS for ameliorating obesity. Deep brain stimulation for treating obesity has been performed both in animals and in humans with intriguing preliminary results. The brain is an attractive target for addressing obesity because modulating brain activity may permit influencing both sides of the energy equation--caloric intake and energy expenditure.

Deep Brain Stimulation for Obesity: From a Theoretical Framework to Practical Application.

Obesity remains a pervasive global health problem. While there are a number of nonsurgical and surgical options for treatment, the incidence of obesity continues to increase at an alarming rate. The inability to curtail the growing rise of the obesity epidemic may be related to a combination of increased food availability and palatability. Research into feeding behavior has yielded a number of insights into the homeostatic and reward mechanisms that govern feeding. However, there remains a gap between laboratory investigations of feeding physiology in animals and translation into meaningful treatment options for humans. In addition, laboratory investigation may not be able to recapitulate all aspects of human food consumption. In a landmark pilot study of deep brain stimulation (DBS) of the lateral hypothalamic area for obesity, we found that there was an increase in resting metabolic rate as well as a decreased urge to eat. In this review, the authors will review some of the work relating to feeding physiology and research surrounding two nodes involved in feeding homeostasis, nucleus accumbens (NAc) and hypothalamus, and use this to provide a framework for future investigations of DBS as a viable therapeutic modality for obesity.

Pursuing new targets and indications for deep brain stimulation: considerations for device-related clinical research in the United States.

DBS surgical research is particularly challenging since the FDA has classified DBS as a class III or “significant risk device.” To study novel targets or indications for a “significant risk device,” an investigator must obtain both FDA and institutional review board (IRB) approval. We believe that investigators should be better informed about the barriers surrounding medical device research and we would like to provide a roadmap for conducting investigational DBS surgery in humans.

Stimulation of the globus pallidus internus in a patient with DYT1-positive primary generalized dystonia: a 10-year follow-up

The authors report the case of DYT1-positive primary generalized dystonia refractory to medical management that was successfully treated with continuous deep brain stimulation of the internal segment of the globus pallidus. Prior studies have shown that neuromusculoskeletal deficits can remain permanent if early surgical intervention is not undertaken. The authors report prolonged efficacy and safety over a 10-year period in a 28-year-old man.