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Joel D MacDonald

Publications and source records attributed to Joel D MacDonald.

13 recordsLinked to original sources
PubMed2006

Acute microelectrode array implantation into human neocortex: preliminary technique and histological considerations.

OBJECT: Researchers at The Center for Neural Interfaces at the University of Utah have designed and produced a silicon-based high-density microelectrode array that has been used successfully in mammalian models. The authors investigate the ability to transfer array insertion techniques to humans and examine the acute response of human cortical tissue to array implantation. METHODS: Six patients who were scheduled to undergo temporal lobectomy surgery were enrolled in an Institutional Review Board-approved protocol. Before the patients underwent lateral temporal cortical resection, one or two high-density microelectrode arrays were implanted in each individual by using a pneumatic insertion device. Cortical tissue was then excised and preserved in formalin. The specimens were sectioned and stained for histological examination. Pneumatic insertion of a microelectrode array into human cortex in the operating room was feasible. There were no clinical complications associated with implantation and no evidence of significant insertion-related hemorrhage. Tissue responses ranged from mild cortical deformity to small focal hemorrhages several millimeters below the electrode tines. Based on initial results, the insertion device was modified. A footplate that mechanically isolates a small area of cortex and a calibrated micromanipulator were added to improve the reproducibility of insertion. CONCLUSIONS: A high-density microelectrode array designed to function as a direct cortical interface device can be implanted into human cortical tissue without acute clinical complications. Further modifications to the insertion device and array design are ongoing and future work will assess the functional significance of the tissue reactions observed.

Electrodes, Implanted↗
PubMed2006

Surgical strategies for recurrent craniofacial meningiomas.

OBJECTIVE: Recurrent cranial base meningiomas are among the most difficult tumors to treat surgically. Although they are histologically benign, these tumors often invade through the cranial base into the infratemporal and pterygopalatine fossae. We reviewed our experience with these tumors to describe the natural history of these lesions as well as provide a possible treatment paradigm. METHODS: Between 2000 and 2004, seven patients with meningiomas recurring through the cranial base into facial structures were treated at the University of Utah. Five patients were treated with transcranial approaches only, and two were treated with a combination of transcranial and transfacial approaches. RESULTS: The average age of our patients (6 women, 1 man) was 55 years. The original site of tumor was the sphenoid wing in four patients, the middle fossa in two patients, and the left frontal region in one patient. The average interval between the most recent tumor resection and recurrence into the face was 9.9 years. The mean number of resections a patient underwent before invasion into the face was two. All but one patient had adjunctive therapy (including either radiation or chemotherapy) before recurrence into the face. CONCLUSION: Meningiomas that recur into facial structures present a unique treatment challenge. These lesions have a high rate of recurrence once they have invaded through the cranial base. Although combined approaches may be necessary to achieve a gross total resection, these lesions can often be reached using standard transcranial techniques.

Adult↗
PubMed2006

Cervical catheter tip placement for intrathecal baclofen administration.

OBJECTIVE: Intrathecal baclofen can reduce congenital and posttraumatic spasticity. Traditionally, the catheter tip for baclofen delivery is placed in a low thoracic position, which can result in a lumbar-to-cisternal cerebrospinal fluid baclofen concentration gradient. We investigated whether more rostral catheter placement was technically feasible, safe, and able to control upper extremity spasticity. METHODS: The records of 48 patients with a baclofen pump were reviewed retrospectively to evaluate the safety and efficacy of cervically placed intrathecal catheters for baclofen administration. Twenty-three patients had a catheter located in a cervical position and 25 had a catheter in a thoracic position (control group). Complications, including baclofen overdose, mechanical failures, and infections, were noted. Pre- and postoperative Ashworth scores were determined by a physical therapist using a standardized protocol. RESULTS: The mean duration of the follow-up period was 10 months. The groups were not significantly different in patient age, baclofen dose, or duration of follow-up, but differed somewhat in the causes of spasticity. For patients with a cervical catheter tip position, upper extremity Ashworth scores decreased significantly from 4.0 +/- 0.8 (standard deviation) preoperatively to 3.0 +/- 0.9 postoperatively (P = 0.003). In both groups, lower extremity spasticity was significantly reduced. Postoperatively, one patient with a cervical catheter developed aspiration pneumonia, possibly because of sedation. Other complications included hardware infections, mechanical malfunctions, and pseudomeningoceles. CONCLUSION: In this series, placement of intrathecal baclofen catheters in the cervical region resulted in equal control of spasticity in the upper and lower extremities and did not increase complications related to the catheter position.

Adolescent↗
PubMed2006

Self-assessment in neurological surgery: the SANS wired white paper.

OBJECTIVE: Periodic self-assessment is an important component of postgraduate medical education and certification. The Self-assessment in Neurological Surgery (SANS) examination has a history of usefulness for neurosurgical written and oral board examination preparation. The SANS Wired test represents a recreation of the original SANS test using an Internet-based platform. Advanced functionality and contemporary content have been added to meet the increasing requirements for demonstration of lifelong learning and self-assessment as part of the Maintenance of Certification (MOC) process. METHODS: A needs assessment was performed before the development of SANS Wired. Postexamination surveys for users obtaining continuing medical education credit were analyzed for user satisfaction with the platform and content. Test-item performance metrics were analyzed based on first-attempt responses. The economic value of SANS Wired as a component of the mandatory MOC process was evaluated. RESULTS: The needs assessment identified a deficiency of available content and mechanisms for neurosurgery-specific self-assessment. As of October 15, 2005, a total of 588 individuals had subscribed to SANS Wired (28 institutional licenses accounted for 229 users). Eighty-eight post-test surveys were analyzed for user satisfaction. Ninety-four percent of responses indicated that learning objectives had been met. Initial performance metrics show an average point-biserial discrimination index of +0.18 for all test items. CONCLUSION: The SANS Wired system seems to be an effective platform for neurosurgical self-assessment and is acceptable to users. The system satisfies, in part, two of the four required components of MOC, namely, periodic self-assessment and demonstration of cognitive expertise. It is endorsed by the American Board of Neurological Surgeons for MOC.

Certification↗
PubMed2005

Learning to perform microvascular anastomosis.

The skills necessary to connect ultrasmall vessels and neural structures successfully require commitment and practice to refine. The techniques require only a few specialized instruments and a high-quality microscope. Several exercises can simulate real-life anatomical situations using a rubber sheet, chicken vessels, or the rat femoral artery model. A series of graduated drills can help develop proficiency and confidence.

Journal Article↗
PubMed2005

Percutaneous dilational tracheostomy in neurosurgical patients.

INTRODUCTION: Tracheostomy is often performed in patients requiring long-term mechanical ventilation after severe neurological injury. Percutaneous dilational tracheostomy (PDT) is an alternative to traditional surgical tracheostomy (TST) for creating a tracheostomy. We compared these techniques in neurosurgical patients and assessed the impact on cost and clinical course. METHODS: We conducted a retrospective chart review of 81 neurosurgical patients treated with either PDT (n = 43) or TST (n = 38). Several clinical endpoints were examined, including days intubated prior to tracheostomy, length of hospital stay, procedural complications, and overall procedure costs. RESULTS: No serious complications occurred with PDT, whereas two minor postoperative complications occurred in the TST group. The time from intubation to tracheostomy was 8 days for the PDT group versus 13 days for the TST group (p < 0.001), and the time from intubation to discharge from the hospital was 20 days for the PDT group compared to 27 days for the TST group (p < 0.005). In our institution, the average cost of PDT was $980.69 less than the cost for TST. CONCLUSION: PDT appears to have a low incidence of complications in neurosurgical patients and may shorten the length of hospitalization and the overall cost compared with TST.

Adult↗
PubMed2005

CNS Internet tools and neurosurgery.

The CNS has developed a collection of online tools for the benefit of the public and the neurosurgical community. The CNS website, CNS PA, and SANS Wired all facilitate information access, communication, and education. Each of these applications takes advantage of the power of the Internet as a high-speed, asynchronous digital data storage and retrieval system. The CNS has designed and compiled these features with the objective of making these tools an easily accessible and integral part of neurosurgical education and practice.

Central Nervous System↗
PubMed2004

Marked reduction of cerebral vasospasm with lumbar drainage of cerebrospinal fluid after subarachnoid hemorrhage.

OBJECT: Cerebral vasospasm after subarachnoid hemorrhage (SAH) continues to be a major source of morbidity in patients despite significant clinical and basic science research. Efforts to prevent vasospasm by removing spasmogens from the subarachnoid space have produced mixed results. The authors hypothesize that lumbar cisternal drainage can remove blood from the basal subarachnoid spaces more effectively than an external ventricular drain (EVD). This non-randomized, controlled-cohort study was undertaken to evaluate the effectiveness of a lumbar drain in patients with SAH compared with those in whom an EVD or no form of cerebrospinal fluid (CSF) drainage was used to prevent the development of clinical vasospasm and its sequelae. METHODS: The authors collected data on 266 patients with nontraumatic SAH who were admitted to the University of Utah Health Sciences Center between January 1994 and January 2003. Of these, 167 met the study entry criteria. The treatment group consisted of 81 patients in whom a lumbar drain had been placed for CSF shunting, whereas the control group was composed of 86 patients who received no form of CSF drainage or who were treated solely with an EVD. Primary outcome measures were as follows: 1) clinically evident vasospasm; 2) the need for endovascular intervention; 3) vasospasm-induced infarction; 4) disposition at time of discharge; and 5) Glasgow Outcome Scale (GOS) score at 1 to 3 months postdischarge. Secondary outcomes included length of stay and the need for CSF shunting. The presence of a lumbar drain conferred a statistically significant protective and beneficial effect across all outcome measures, reducing the incidence of clinical vasospasm from 51 to 17%, the need for angioplasty from 45 to 17%, and the occurrence of vasospastic infarction from 27 to 7% (all p < or = 0.001-0.008). Patients in the treatment group were more likely to be discharged home (54% compared with 25%, p = 0.002) and to have a GOS score of 5 at follow up (71% compared with 35%, p < 0.001). The mean number of days spent in the intensive care unit and in the hospital overall was also fewer in the treatment group. A similar degree of benefit was found in patients with different Fisher grades and regardless of whether an EVD was needed on presentation, both by subgroup analysis and multivariate logistic regression modeling. There was no statistical difference between the groups in terms of patients requiring a shunt. Complications with lumbar drains were rare and yielded no permanent sequelae. CONCLUSIONS: Shunting of CSF through a lumbar drain after an SAH markedly reduces the risk of clinically evident vasospasm and its sequelae, shortens hospital stay, and improves outcome. Its beneficial effects are probably mediated through the removal of spasmogens that exist in the CSF. The results of this study warrant a randomized clinical trial, which is currently under way.

Adult↗
PubMed2004

Efficacy of multiple intraarterial papaverine infusions for improvement in cerebral circulation time in patients with recurrent cerebral vasospasm.

OBJECT: Cerebral vasospasm that is caused by aneurysmal subarachnoid hemorrhage and that is refractory to maximal medical management can be treated with selective intraarterial papaverine infusions. The effects of single papaverine treatments on cerebral circulation time are well known. The purpose of this study was to assess the efficacy of multiple, repeated papaverine infusions on the cerebral circulation time in patients with recurrent vasospasm. METHODS: A retrospective study was conducted in 17 patients who received multiple intraarterial papaverine infusions in 91 carotid artery (CA) territories for the treatment of cerebral vasospasm. Cerebral circulation times were measured from the first angiographic image, in which peak contrast was seen above the supraclinoid internal CA, to the peak filling of cortical veins. Glasgow Outcome Scale (GOS) scores assessed 12 months after discharge were reviewed. Cerebral circulation times in 16 CA territories were measured in a control group of 11 patients. Seventeen patients received a total of 91 papaverine treatments. Prolonged cerebral circulation times improved after 90 (99%) of 91 papaverine treatments. The prepapaverine mean cerebral circulation time was 6.54 seconds (range 3.35-27 seconds) and the immediate postpapaverine mean cerebral circulation time was 4.19 seconds (range 2.1-12.6 seconds), an overall mean decrease of 2.35 seconds (36%, p < 0.001). Recurrent vasospasm reflected by prolonged cerebral circulation times continued to improve with subsequent papaverine infusions. Repeated infusions were just as successful quantitatively as the primary treatment (mean change 2.06 seconds). The mean cerebral circulation time in the control group was 5.21 seconds (range 4-6.8 seconds). In five patients a dramatic reversal of low-attenuation changes was detected on computerized tomography scans. The mean GOS score at 12 months after discharge was 3.4. CONCLUSIONS: The preliminary results indicate that multiple intraarterial papaverine treatments consistently improve cerebral circulation times, even with repeated infusions in cases of recurrent vasospasm.

Adult↗
PubMed2004

Surgical considerations regarding giant dilations of the perivascular spaces.

OBJECT: Dilations of brain perivascular spaces (PVSs), also known as Virchow-Robin spaces, are routinely identified on magnetic resonance imaging studies of the brain and recognized as benign normal variants. Giant dilations occur only rarely and can be easily misdiagnosed as central nervous system tumors. The relevant surgical literature was reviewed to help establish indications for surgical intervention in these typically benign lesions. METHODS: Giant dilations of the PVSs in 12 patients who had undergone surgery for several different indications were identified. Both clinical and radiographic presentations of these patients were reviewed along with the surgical procedures. CONCLUSIONS: Dilations of the PVSs can become giant lesions that may necessitate surgical intervention to relieve mass effect or hydrocephalus. The relationship of these lesions to neurological symptoms such as tremor and seizures remains unclear.

Adult↗
PubMed2003

Hypophysial transposition (hypophysopexy) for radiosurgical treatment of pituitary tumors involving the cavernous sinus. Technical note.

Stereotactic radiosurgery (SRS) is performed with increasing frequency in the treatment of residual or recurrent pituitary adenomas. Its major associated risk in these cases of residual or recurrent pituitary tumor adjacent to normal functional pituitary gland is radiation exposure to the pituitary, which frequently leads to the development of hypopituitarism. The authors describe a technique of pituitary transposition to reduce the radiation dose to the normal pituitary gland in cases of planned radiosurgical treatment of residual pituitary adenoma within the cavernous sinus. A sellar exploration for tumor resection is performed, the pituitary gland is transposed from the region of the cavernous sinus, and a fat and fascia graft is interposed between the normal pituitary gland and the residual tumor in the cavernous sinus. The residual tumor may then be treated with SRS. The increased distance between the normal pituitary gland and the residual tumor facilitates treatment of the tumor with radiosurgery and reduces radiation exposure to the normal pituitary gland.

Adolescent↗
PubMed2003

Extensive experience with dural sinus thrombosis.

OBJECTIVE: Dural sinus thrombosis (DST) is an uncommon cause of stroke. The safest and most effective therapy for DST has not been conclusively identified. METHODS: A retrospective chart review of data for 31 patients who were treated for DST at our institution between 1992 and 2001 was performed. Four treatment strategies were identified, i.e., 1). medical observation only, 2). systemic anticoagulation (AC) therapy with heparin, 3). endovascular chemical thrombolysis with urokinase or tissue plasminogen activator and concurrent systemic AC therapy, and 4). mechanical endovascular clot thrombolysis with concurrent systemic AC therapy. Complications and clinical outcomes were assessed for each group. RESULTS: Patients treated solely with medical observation fared the worst; four of five patients experienced intracranial hemorrhagic complications, and only two of five exhibited clinical improvement. Patients who received systemic AC therapy experienced no hemorrhagic complications, even when pretreatment hemorrhage was present; 75% (six of eight patients) exhibited improvement with AC therapy alone. Chemical thrombolysis was very effective in restoring sinus patency (90% of patients); however, 30% of patients (3 of 10 patients) experienced hemorrhagic complications. Sixty percent of patients (6 of 10 patients) who underwent chemical thrombolysis exhibited clinical improvement. Patients who underwent mechanical thrombectomies demonstrated a low hemorrhagic complication rate, and most (88%) made good recoveries. CONCLUSION: Therapy directed at the underlying clot in DST must begin without delay. Our results suggest that supportive medical management of DST, without therapy directed at the clot or clotting process, is not effective. Systemic AC therapy, even in the presence of intracerebral hemorrhage, seems to be safe. Heparin can be safely titrated to yield partial thromboplastin times of 60 to 70 seconds. Chemical clot thrombolysis is efficacious in opening occluded sinuses but may cause intracranial hemorrhage. We currently recommend either systemic AC therapy or systemic AC therapy in conjunction with mechanical clot thrombectomy as a safe effective treatment for DST.

Adolescent↗