Biomedical subjects
Publications and source records attributed to Parag G Patil.
Tourette syndrome is a common neurologic disorder with close ties to obsessive-compulsive disorder and attention-deficit hyperactivity disorder (ADHD). The majority of patients improve spontaneously as they near adulthood. Most others are effectively treated with pharmacologic agents, although these therapies fail for an unfortunate few. For patients debilitated by the disease despite medical therapy, surgery can become an important option.
OBJECTIVE: To increase awareness among neurosurgeons of alternative surgical approaches to lesions of the sciatic nerve in the gluteal region. METHODS: The dominant surgical approach to lesions of the proximal sciatic nerve involves detachment and medial reflection of the gluteus maximus through a question-mark incision. An alternative to this infragluteal exposure is a transgluteal approach, which provides access to the sciatic nerve by splitting the gluteus maximus through a curvilinear incision. We explored the anatomy and surgical history of these approaches through cadaveric study, our own case series, and a literature review. RESULTS: The infragluteal approach uses a larger incision, extensive dissection, and postoperative bracing while allowing wide exposure of the nerve inferiorly into the thigh. By contrast, the transgluteal approach minimizes dissection and spares muscle attachments but requires meticulous attention to hemostasis and provides a more focal exposure of the sciatic nerve. During the past century, the infragluteal approach has been described more frequently and has become increasingly popular among peripheral-nerve surgeons. For comparison, we present three patients in whom the transgluteal approach was used to treat substantial lesions of the proximal sciatic nerve. CONCLUSION: At the present time, the majority of peripheral nerve surgeons use an infragluteal approach to the proximal sciatic nerve. However, for select patients with well-defined and localized lesions, the transgluteal approach may provide sufficient nerve exposure with lowered operative complexity and postoperative morbidity.
OBJECTIVE: Degenerative cervical spine disease is one of the most common indications for spinal surgical intervention. The impact of the unprecedented changes in healthcare technology and delivery over the past decade is unknown. We examined this issue using the Nationwide Inpatient Sample database, a representative sample of all United States inpatient hospitalizations. METHODS: All adult patients undergoing spinal procedures with a principal diagnosis of cervical spine disease were selected for analysis according to International Classification of Diseases 9th Revision clinical modification codes. Patients diagnosed with infection, neoplasia, fracture, or trauma, as well as those with noncervical or nonspecific principal diagnoses, were excluded. RESULTS: The total number of cervical spine procedures in the sampled population rose twofold, from 53,810 in 1990 to 112,400 in 2000. Anterior fusion procedures rose (17.8-69.5% of procedures), whereas nonfusion decompressions declined sharply (70.5-24.6%). Patient diversity increased with increasing rates of surgery among women (25.0-51.0 per 100,000) and minorities (18.4-45.7 per 100,000). Although average age (47.5-49.2 yr) and medical comorbidities (8.7-13.5% of patients) increased, mortality (0.21-0.14% of hospitalizations) and average length of stay (5.2-2.2 d) declined. Inflation-adjusted hospital charges rose by 48% to a total exceeding 2 billion dollars in 2000. CONCLUSION: Compared with one decade ago, the surgical treatment of degenerative cervical spine disease has evolved to include a higher percentage of anterior and fusion procedures performed on a more diverse, older, and comorbid patient population, with shortened hospital stay and improved morbidity and mortality, although at substantially increased cost.
OBJECTIVE: Patients with severe neurological injury, such as quadriplegics, might benefit greatly from a brain-machine interface that uses neuronal activity from motor centers to control a neuroprosthetic device. Here, we report an implementation of this strategy in the human intraoperative setting to assess the feasibility of using neurons in subcortical motor areas to drive a human brain-machine interface. METHODS: Acute ensemble recordings from subthalamic nucleus and thalamic motor areas (ventralis oralis posterior [VOP]/ventralis intermediate nucleus [VIM]) were obtained in 11 awake patients during deep brain stimulator surgery by use of a 32-microwire array. During extracellular neuronal recordings, patients simultaneously performed a visual feedback hand-gripping force task. Offline analysis was then used to explore the relationship between neuronal modulation and gripping force. RESULTS: Individual neurons (n = 28 VOP/VIM, n = 119 subthalamic nucleus) demonstrated a variety of modulation responses both before and after onset of changes in gripping force of the contralateral hand. Overall, 61% of subthalamic nucleus neurons and 81% of VOP/VIM neurons modulated with gripping force. Remarkably, ensembles of 3 to 55 simultaneously recorded neurons were sufficiently information-rich to predict gripping force during 30-second test periods with considerable accuracy (up to R = 0.82, R(2) = 0.68) after short training periods. Longer training periods and larger neuronal ensembles were associated with improved predictive accuracy. CONCLUSION: This initial feasibility study bridges the gap between the nonhuman primate laboratory and the human intraoperative setting to suggest that neuronal ensembles from human subcortical motor regions may be able to provide informative control signals to a future brain-machine interface.
OBJECTIVE AND IMPORTANCE: Xanthogranulomas involving the central or peripheral nervous system are extraordinarily rare. None have been reported in the lower extremity. Here, we report and characterize the first case of xanthogranuloma of the sciatic nerve. CLINICAL PRESENTATION: A 58-year-old woman presented with poorly localized right back and groin pain. Magnetic resonance imaging studies revealed an enhancing lesion of the sciatic nerve in the right gluteal region. INTERVENTION: The sciatic nerve xanthogranuloma was resected without complication. CONCLUSION: Our report indicates that xanthogranuloma, although extremely rare, may occur throughout the nervous system. Our evaluation demonstrates that such lesions involving the peripheral nervous system have similar pathological characteristics to xanthogranulomas that more commonly occur in the skin.
Reaching and grasping in primates depend on the coordination of neural activity in large frontoparietal ensembles. Here we demonstrate that primates can learn to reach and grasp virtual objects by controlling a robot arm through a closed-loop brain-machine interface (BMIc) that uses multiple mathematical models to extract several motor parameters (i.e., hand position, velocity, gripping force, and the EMGs of multiple arm muscles) from the electrical activity of frontoparietal neuronal ensembles. As single neurons typically contribute to the encoding of several motor parameters, we observed that high BMIc accuracy required recording from large neuronal ensembles. Continuous BMIc operation by monkeys led to significant improvements in both model predictions and behavioral performance. Using visual feedback, monkeys succeeded in producing robot reach-and-grasp movements even when their arms did not move. Learning to operate the BMIc was paralleled by functional reorganization in multiple cortical areas, suggesting that the dynamic properties of the BMIc were incorporated into motor and sensory cortical representations.