Toward Deep Brain Monitoring with Superficial EEG Sensors Plus Neuromodulatory Focused Ultrasound.

Noninvasive recordings of electrophysiological activity have limited anatomic specificity and depth. We hypothesized that spatially tagging a small volume of brain with a unique electroencephalography (EEG) signal induced by pulsed focused ultrasound could overcome those limitations. As a first step toward testing this hypothesis, we applied transcranial ultrasound (2 MHz, 200-ms pulses applied at 1050 Hz for 1 s at a spatial peak temporal average intensity of 1.4 W/cm(2)) to the brains of anesthetized rats while simultaneously recording EEG signals. We observed a significant 1050-Hz electrophysiological signal only when ultrasound was applied to a living brain. Moreover, amplitude demodulation of the EEG signal at 1050 Hz yielded measurement of gamma band (>30 Hz) brain activity consistent with direct measurements of that activity. These results represent preliminary support for use of pulsed focused ultrasound as a spatial tagging mechanism for non-invasive EEG-based mapping of deep brain activity with high spatial resolution.

A survey of complementary and alternative medicine (CAM) awareness among neurosurgeons in Washington State.

OBJECTIVES: Use of complementary and alternative medicine (CAM) by the U.S. population increased significantly in the past 2 decades. To maximize a patient's recovery from a neurosurgical procedure, it is critical that neurosurgeons be aware of the benefits and potential adverse complications of CAM therapies. The survey's purpose was to assess the current patterns of CAM utilization by neurosurgery patients and neurosurgeon knowledge of CAM therapies among Washington State Association of Neurological Surgeons (WSANS) members. METHODS: Members of the WSANS were surveyed in 2005. The survey was sent via e-mail and the data were anonymously collected using an online survey tool, Catalyst WebQ. RESULTS: The majority of responses (79%) stated that their neurosurgery practice was > or =75% adults. Acupuncture, herbs, massage therapy, prayer, and yoga were the most common CAM treatments patients used or discussed with their neurosurgeon. Fifty percent (50%) of neurosurgeons discussed the use of acupuncture among their colleagues. Concerning prayer and spirituality, 38% of the surveyed neurosurgeons stated that > or =25% of their patients have disclosed that they pray for their health; 42% stated that spirituality and prayer may affect neurosurgery outcome; and 38% stated that they pray for their patients. Overall, 63% of surveyed neurosurgeons stated that CAM treatments have a role in neurosurgery. CONCLUSIONS: The use of CAM may influence neurosurgical care; and the role of spirituality and prayer should be further explored. Because CAM utilization is ubiquitous, open discussion and familiarity with CAM treatments are becoming increasingly important in the field of neurosurgery.

Spontaneous subdural fluid collections following transection of a fatty filum terminale: case report and review of the literature.

We present the case of a 6-year-old girl who developed bilateral subdural fluid collections following transection of her fatty filum terminale. The patient presented to our emergency department 3 weeks subsequent to surgery, reporting symptoms of headache, nausea, and vomiting. The presence of bilateral subdural fluid collections was confirmed by head computerized tomography. Subdural fluid collections and hematomas have been associated with intracranial hypotension and excessive cerebrospinal fluid leakage; however, there are relatively few cases of subdural fluid collections/hematomas following spine surgery reported in the literature. To our knowledge, this is a unique description of development and resolution of subdural fluid collections following surgical transection of a fatty filum terminale.

Electrocorticographic frequency alteration mapping: a clinical technique for mapping the motor cortex.

OBJECTIVE: Electrocortical stimulation (ECS) has been well established for delineating the eloquent cortex. However, ECS is still coarse and inefficient in delineating regions of the functional cortex and can be hampered by after-discharges. Given these constraints, an adjunct approach to defining the motor cortex is the use of electrocorticographic signal changes associated with active regions of the cortex. The broad range of frequency oscillations are categorized into two main groups with respect to the sensorimotor cortex: low and high frequency bands. The low frequency bands tend to show a power reduction with cortical activation, whereas the high frequency bands show power increases. These power changes associated with the activated cortex could potentially provide a powerful tool in delineating areas of the motor cortex. We explore electrocorticographic signal alterations as they occur with activated regions of the motor cortex, as well as its potential in clinical brain mapping applications. METHODS: We evaluated seven patients who underwent invasive monitoring for seizure localization. Each patient had extraoperative ECS mapping to identify the motor cortex. All patients also performed overt hand and tongue motor tasks to identify associated frequency power changes in regard to location and degree of concordance with ECS results that localized either hand or tongue motor function. RESULTS: The low frequency bands had a high sensitivity (88.9-100%) and a lower specificity (79.0-82.6%) for identifying electrodes with either hand or tongue ECS motor responses. The high frequency bands had a lower sensitivity (72.7-88.9%) and a higher specificity (92.4-94.9%) in correlation with the same respective ECS positive electrodes. CONCLUSION: The concordance between stimulation and spectral power changes demonstrate the possible utility of electrocorticographic frequency alteration mapping as an adjunct method to improve the efficiency and resolution of identifying the motor cortex.