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Philip V Theodosopoulos

Publications and source records attributed to Philip V Theodosopoulos.

5 recordsLinked to original sources
PubMed2003

Locations of movement-related cells in the human subthalamic nucleus in Parkinson's disease.

The subthalamic nucleus (STN) is an emerging target for deep brain stimulator (DBS) implantation for the treatment of advanced Parkinson's disease (PD). Understanding the somatotopic organization of the STN is important for surgical navigation within the nucleus. We analyzed intraoperative data obtained during 54 procedures for the implantation of STN stimulators to assess the locations of movement-related cells. Cells were considered movement-related if they exhibited modulation of the cell discharge during passive movement of the contralateral upper or lower extremity. Microelectrode track reconstructions were plotted on a human brain atlas, using the location of the DBS electrode from postoperative magnetic resonance images as a registration mark in reconstructing microelectrode track locations. Movement-related cells were predominantly located in the dorsal part of the nucleus. The majority of the cells were related to proximal joint manipulation. Arm-related cells were located laterally and at the rostral and caudal poles, whereas leg-related cells were located medially and centrally. The finding of three or more leg-related cells on a given microelectrode track was predictive of a medial localization within the motor area. Our findings are consistent with the small number of published studies on STN somatopy in the human and the nonhuman primate.

Action Potentials↗
PubMed2003

Surgery of the subthalamic nucleus: use of movement-related neuronal activity for surgical navigation.

THE BASAL GANGLIA have important roles in somatic motor, oculomotor, limbic, and associative functions. These functions are represented in anatomically distinct territories in each basal ganglion nucleus. During surgery of the subthalamic nucleus for Parkinson's disease, the primary goal is to influence the physiology of the motor territory without affecting nonmotor areas. This article describes the use of movement-related cellular activity during single-unit microelectrode mapping to identify and to navigate within the motor territory of the subthalamic nucleus.

Brain Mapping↗
PubMed2002

Predictive model for pain recurrence after posterior fossa surgery for trigeminal neuralgia.

BACKGROUND: Surgical exploration of the posterior fossa is the definitive treatment for trigeminal neuralgia refractory to medication, but predictors of its success in effecting long-term pain relief have not been established. OBJECTIVE: To develop a model that allows stratification of patients' risk of postoperative recurrence of pain based on pretreatment factors. METHODS: We reviewed the records of 420 consecutive patients who underwent posterior fossa exploration by one of us (C.B.W.) for the treatment of idiopathic trigeminal neuralgia. The primary outcome measure was recurrence of trigeminal pain. The predictive value of preoperative and intraoperative factors was evaluated. Multivariate analysis revealed the statistically significant predictors of pain recurrence, permitting creation of a risk model for recurrence of pain. RESULTS: After surgery, trigeminal pain had lessened in 98% of patients and completely resolved in 87%. There were no perioperative deaths. After a mean follow-up of 56.3 months, 93% of patients reported significant pain improvement and 72% continued to have no pain. The estimated likelihood of pain recurrence at 8 years was 34%. Significant predictors of eventual recurrence of pain were age younger than 53 years at the time of surgery, symptoms lasting longer than 11(1/2) years, female sex, and pain on the left side in men. These factors were weighted and incorporated into a risk model that revealed 4-year pain-free survival of 89% +/- 4% for the low-risk group, 80% +/- 4% for the moderate-risk group, and 58% +/- 6% for the high-risk group (data are mean +/- SD). CONCLUSIONS: We developed a predictive model that stratifies the risk for eventual recurrence of pain after posterior fossa exploration for trigeminal neuralgia. This information may be useful in counseling patients regarding treatment.

Disease-Free Survival↗
PubMed2002

Implantation of deep brain stimulators into the subthalamic nucleus: technical approach and magnetic resonance imaging-verified lead locations.

OBJECT: Chronic deep brain stimulation (DBS) of the subthalamic nucleus (STN) is a procedure that is rapidly gaining acceptance for the treatment of symptoms in patients with Parkinson disease (PD), but there are few detailed descriptions of the surgical procedure itself. The authors present the technical approach used to implant 76 stimulators into the STNs of patients with PD and the lead locations, which were verified on postoperative magnetic resonance (MR) images. METHODS: Implantation procedures were performed with the aid of stereotactic MR imaging, microelectrode recording (MER) in the region of the stereotactic target to define the motor area of the STN, and intraoperative test stimulation to assess the thresholds for stimulation-induced adverse effects. All patients underwent postoperative MR imaging, which was performed using volumetric gradient-echo and T2-weighted fast-spin echo techniques, computational reformatting of the MR image into standard anatomical planes, and quantitative measurements of lead location with respect to the midcommissural point and the red nucleus. Lead locations were statistically correlated with physiological data obtained during MER and intraoperative test stimulation. CONCLUSIONS: The authors' approach to implantation of DBS leads into the STN was associated with consistent lead placement in the dorsolateral STN, a low rate of morbidity, efficient use of operating room time, and robust improvement in motor function. The mean coordinates of the middle of the electrode array, measured on postoperative MR images, were 11.6 mm lateral, 2.9 mm posterior, and 4.7 mm inferior to the midcommissural point, and 6.5 mm lateral and 3.5 mm anterior to the center of the red nucleus. Voltage thresholds for several types of stimulation-induced adverse effects were predictive of lead location. Technical nuances of the surgery are described in detail.

Aged↗