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Andrew H. Kaye, John R. Little, Bernadine Bryerton and Michael Modic

✓ Preoperative intravenous digital subtraction angiography (IV DSA) was compared with the operative findings in 54 patients who underwent a total of 57 carotid endarterectomies, to evaluate the accuracy of preoperative IV DSA in predicting the lesion found at surgery. Four studies early in the series were technically unsatisfactory, leaving 50 patients with 53 procedures for evaluation. Severe carotid artery stenosis was accurately predicted in all cases. Deep ulceration in the absence of severe carotid stenosis was reliably shown by IV DSA, although it was not reliably demonstrated by either IV DSA or carotid angiography if severe stenosis was also present. As severe carotid stenosis or deep ulceration are the major radiological indications for carotid endarterectomy, the authors have found that technically satisfactory IV DSA is an adequate preoperative imaging technique.

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Andrew S. Little, John F. Kerrigan, Cameron G. McDougall, Joseph M. Zabramski, Felipe C. Albuquerque, Peter Nakaji and Robert F. Spetzler

Object

Nonconvulsive status epilepticus (NCSE) is an underrecognized and poorly understood complication of aneurysmal subarachnoid hemorrhage (SAH). The authors evaluated the risk factors, electroencephalographic (EEG) characteristics, hospital course, and clinical outcomes associated with NCSE in a population with SAH treated at a single institution.

Methods

The hospitalization and outcome data were reviewed in 11 patients who had received a diagnosis of NCSE and SAH. The study included individuals from a cohort of 389 consecutive patients with SAH who were treated between March 2003 and June 2005, and who were analyzed retrospectively. The patients' medical history, neurological grade, events of hospitalization, EEG morphological patterns, and disposition were analyzed.

Advanced age, female sex, need for ventriculostomy, poor neurological grade (Hunt and Hess Grade III, IV, or V), thick cisternal blood clots, and structural lesions (intracerebral hemorrhage and stroke) were common in the population with NCSE. Patients with normal results on angiograms, good neurological grade (Hunt and Hess Grade I or II), and minimal SAH (Fisher Grade 1 or 2) were at lower risk. The most common ictal patterns were intermittent, and consisted of generalized periodic epileptiform discharges. Medical complications were also frequent, and the outcome of these patients was poor despite aggressive treatment regimens.

Conclusions

Nonconvulsive status epilepticus is a devastating complication of SAH with a high rate of associated morbidity. Based on these findings it appears that the patients at highest risk for NCSE can be identified, and this should provide a basis for further studies designed to determine the clinical significance of various EEG patterns and to develop preventative strategies.

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Andrew S. Little, Kris A. Smith, Kristin Kirlin, Leslie C. Baxter, Steve Chung, Rama Maganti and David M. Treiman

Object

The authors introduce a minimal-access subtemporal approach for selective resection of the amygdala and hippocampus in patients with temporal lobe epilepsy and describe seizure and neuropsychological outcomes.

Methods

Between October 2003 and April 2007, 41 consecutive patients with intractable unilateral nonlesional temporal lobe epilepsy underwent image-guided subtemporal amygdalohippocampectomy. Baseline characteristics, preoperative evaluations, and seizure outcomes were assessed. Eighteen patients underwent pre- and postoperative neuropsychological testing for cognitive functioning, executive functioning, verbal and visual memory, and mood.

Results

Important aspects of the subtemporal approach include a low temporal keyhole craniotomy, use of image guidance, preservation of the tentorium, incision in the fusiform gyrus, and subpial, en bloc resection of the hippocampus. There were no deaths and no cases of significant postoperative morbidity. At 1 year, 29 of 36 patients (81%) were without seizures or auras. At 2 years, 17 of 23 (74%) patients were seizure- and aura-free. Detailed neuropsychological testing of language, memory, cognitive functioning, and executive functioning suggested that most patients exhibited either stability or improvement in their scores, regardless of language lateralization.

Conclusions

A minimal-access subtemporal approach for amygdalohippocampectomy is an effective treatment for temporal lobe epilepsy yielding encouraging preliminary seizure and neuropsychological outcomes.

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M. Yashar S. Kalani, Nikolay L. Martirosyan, Andrew S. Little, Udaya K. Kakarla and Nicholas Theodore

The authors describe a rare case of tumoral calcinosis (TC) of the thoracic spine in a 13-year-old boy with thoracic scoliosis. The patient presented with a 2-year history of back pain. He had no personal or family history of bone disease, deformity, or malignancy. Magnetic resonance imaging revealed a heterogeneously enhancing mass involving the T-7 vertebral body and the left pedicle. Computed tomography findings suggested that the mass was calcified and that this had resulted in scalloping of the vertebral body. The lesion was resected completely by using a left T-7 costotransversectomy and corpectomy. The deformity was corrected with placement of a vertebral body cage and pedicle screw fixation from T-5 to T-9. Pathological analysis of the mass demonstrated dystrophic calcification with marked hypercellularity and immunostaining consistent with TC. This represents the third reported case of vertebral TC in the pediatric population. Pediatric neurosurgeons should be familiar with lesions such as TC, which may be encountered in the elderly and in hemodialysis-dependent populations, and may not always require aggressive resection.

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Ali M. Elhadi, Samuel Kalb, Luis Perez-Orribo, Andrew S. Little, Robert F. Spetzler and Mark C. Preul

The field of anatomy, one of the most ancient sciences, first evolved in Egypt. From the Early Dynastic Period (3100 bc) until the time of Galen at the end of the 2nd century ad, Egypt was the center of anatomical knowledge, including neuroanatomy. Knowledge of neuroanatomy first became important so that sacred rituals could be performed by ancient Egyptian embalmers during mummification procedures. Later, neuroanatomy became a science to be studied by wise men at the ancient temple of Memphis. As religious conflicts developed, the study of the human body became restricted. Myths started to replace scientific research, squelching further exploration of the human body until Alexander the Great founded the city of Alexandria. This period witnessed a revolution in the study of anatomy and functional anatomy. Herophilus of Chalcedon, Erasistratus of Chios, Rufus of Ephesus, and Galen of Pergamon were prominent physicians who studied at the medical school of Alexandria and contributed greatly to knowledge about the anatomy of the skull base. After the Royal Library of Alexandria was burned and laws were passed prohibiting human dissections based on religious and cultural factors, knowledge of human skull base anatomy plateaued for almost 1500 years. In this article the authors consider the beginning of this journey, from the earliest descriptions of skull base anatomy to the establishment of basic skull base anatomy in ancient Egypt.

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Andrew S. Little, Luis Perez-Orribo, Nestor G. Rodriguez-Martinez, Phillip M. Reyes, Anna G. U. S. Newcomb, Daniel M. Prevedello and Neil R. Crawford

Object

Endoscopic endonasal approaches to the craniovertebral junction (CVJ) and clivus are increasingly performed for ventral skull-base pathology, but the biomechanical implications of these approaches have not been studied. The aim of this study was to investigate the spinal biomechanics of the CVJ after an inferior-third clivectomy and anterior intradural exposure of the foramen magnum as would be performed in an endonasal endoscopic surgical strategy.

Methods

Seven upper-cervical human cadaveric specimens (occiput [Oc]–C2) underwent nondestructive biomechanical flexibility testing during flexion-extension, axial rotation, and lateral bending at Oc–C1 and C1–2. Each specimen was tested intact, after an inferior-third clivectomy, and after ligamentous complex dissection simulating a wide intradural exposure using an anterior approach. Angular range of motion (ROM), lax zone, and stiff zone were determined and compared with the intact state.

Results

Modest, but statistically significant, hypermobility was observed after inferior-third clivectomy and intradural exposure during flexion-extension and axial rotation at Oc–C1. Angular ROM increased incrementally between 6% and 12% in flexion-extension and axial rotation. These increases were primarily the result of changes in the lax zone. No significant changes were noted at C1–2.

Conclusions

Inferior-third clivectomy and an intradural exposure to the ventral CVJ and foramen magnum resulted in hypermobility at Oc–C1 during flexion-extension and axial rotation. Although the results were statistically significant, the modest degree of hypermobility observed compared with other well-characterized CVJ injuries suggests that occipitocervical stabilization may be unnecessary for most patients.

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Andrew S. Little and Kristina Chapple

Object

The short-term cost associated with subspecialized surgical care is an increasingly important metric and economic concern. This study sought to determine factors associated with hospital charges in patients undergoing transsphenoidal surgery for Cushing disease in an effort to identify the drivers of resource utilization.

Methods

The authors analyzed the Nationwide Inpatient Sample (NIS) hospital discharge database from 2007 to 2009 to determine factors that influenced hospital charges in patients who had undergone transsphenoidal surgery for Cushing disease. The NIS discharge database approximates a 20% sample of all inpatient admissions to nonfederal US hospitals. A multistep regression model was developed that adjusted for patient demographics, acuity measures, comorbidities, hospital characteristics, and complications.

Results

In 116 hospitals, 454 transsphenoidal operations were performed. The mean hospital charge was $48,272 ± $32,060. A multivariate regression model suggested that the primary driver of resource utilization was length of stay (LOS), followed by surgeon volume, hospital characteristics, and postoperative complications. A 1% increase in LOS increased hospital charges by 0.60%. Patient charges were 13% lower when performed by high-volume surgeons compared with low-volume surgeons and 22% lower in large hospitals compared with small hospitals. Hospital charges were 12% lower in cases with no postoperative neurological complications. The proposed model accounted for 46% of hospital charge variance.

Conclusions

This analysis of hospital charges in transsphenoidal surgery for Cushing disease suggested that LOS, hospital characteristics, surgeon volume, and postoperative complications are important predictors of resource utilization. These findings may suggest opportunities for improvement.

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Andrew S. Little, Daniel Kelly, John Milligan, Chester Griffiths, Gail Rosseau, Daniel M. Prevedello, Ricardo Carrau, Heidi Jahnke, Charlene Chaloner, Judith O'Leary, Kristina Chapple, Peter Nakaji and William L. White

Object

Patient-reported quality-of-life (QOL) end points are becoming increasingly important health care metrics. To date, no nasal morbidity instrument specifically designed for patients undergoing endonasal skull base surgery has been developed. In this study, the authors describe the development and validation of a site-specific nasal morbidity instrument to assess patient-reported rhinological outcomes following endonasal skull base surgery.

Methods

Eligible patients included those with planned endonasal transsphenoidal surgery for sellar pathology identified in outpatient neurosurgical clinics of 3 skull base centers from October 2011 to July 2012. An initial 23-question pool was developed by subject matter experts, review of the literature, and from the results of a previous validation study to assess for common rhinological complaints. Symptoms were ranked by patients from “No Problem” to “Severe Problem” on a 6-point Likert scale. Exploratory factor analysis, change scores, and importance rank were calculated to define the final instrument consisting of 12 items (The Anterior Skull Base Nasal Inventory-12, or ASK Nasal-12). Psychometric validation of the final instrument was performed using standard statistical techniques.

Results

One hundred four patients enrolled in the study. All patients completed the preoperative survey and 100 patients (96%) completed the survey 2–4 weeks after surgery. Internal consistency of the final instrument was 0.88. Concurrent validity measures demonstrated a strong correlation between overall nasal functioning and total scores (p < 0.001). Test-retest reliability measures demonstrated a significant intraclass correlation between responses (p < 0.001). Effect size as calculated by standardized response mean suggested a large effect (0.84). Discriminant validity calculations demonstrated that the instrument was able to discriminate between preoperative and postoperative patients (p < 0.001).

Conclusions

This prospective study demonstrates that the ASK Nasal-12 is a validated, site-specific, unidimensional rhinological outcomes tool sensitive to clinical change. It can be used in conjunction with multidimensional QOL instruments to assess patient-reported nasal perceptions in endonasal skull base surgery. This instrument is being used as a primary outcome measure in an ongoing multicenter nasal morbidity study. Clinical trial registration no.: NCT01504399 (ClinicalTrials.gov).

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Scott D. Wait, M. Yashar S. Kalani, Andrew S. Little, Giac D. Consiglieri, Jeffrey S. Ross, Matthew R. Kucia, Volker K. H. Sonntag and Nicholas Theodore

Object

Patients who develop a lower-extremity neurological deficit after lumbar laminectomy present a diagnostic dilemma. In the setting of a neurological deficit, some surgeons use MRI to evaluate for symptomatic compression of the thecal sac. The authors conducted a prospective observational cohort study in patients undergoing open lumbar laminectomy for neurogenic claudication to document the MRI appearance of the postlaminectomy spine and to determine changes in thecal sac diameter caused by the accumulation of epidural fluid.

Methods

Eligible patients who were candidates for open lumbar laminectomy for neurogenic claudication at a single neurosurgical center between August 2007 and June 2009 were enrolled. Preoperative and postoperative MRI of the lumbar spine was performed on the same MRI scanner. Postoperative MRI studies were completed within 36 hours of surgery. Routine clinical and surgical data were collected at the preoperative visit, during surgery, and postoperatively. Images were interpreted for the signal characteristics of the epidural fluid and for thecal diameter (region of interest [ROI]) by 2 blinded neuroradiologists.

Results

Twenty-four patients (mean age 69.7 years, range 30–83 years) were enrolled, and 20 completed the study. Single-level laminectomy was performed in 6 patients, 2-level in 12, and 3-level in 2. Preoperative canal measurements (ROI) at the most stenotic level averaged 0.26 cm2 (range 0.0–0.46 cm2), and postoperative ROI at that same level averaged 0.95 cm2 (range 0.46–2.05 cm2). The increase in ROI averaged 0.69 cm2 (range 0.07–1.81 cm2). Seven patients (35%) had immediate postoperative weakness in at least 1 muscle group graded at 4+/5. The decline in examination was believed to be effort dependent and secondary to discomfort in the acute postoperative period. Those with weakness had smaller increases in ROI (0.51 cm2) than those with full strength (0.78 cm2, p = 0.1599), but none had evidence of worsened thecal compression. On the 1st postoperative day, 19 patients were at full strength and all patients were at full strength at their 15-day follow-up. The T1-weighted epidural fluid signal was isointense in 19 of the 20 patients. The T2-weighted epidural fluid signal was hyperintense in 9, isointense in 4, and hypointense in 7 patients.

Conclusions

Immediately after lumbar laminectomy, the appearance of the thecal sac on MRI can vary widely. In most patients the thecal sac diameter increases after laminectomy despite the presence of epidural blood. In this observational cohort, a reduction in thecal diameter caused by epidural fluid did not correlate with motor function. Results in the small subset of patients where the canal diameter decreased due to epidural fluid compression of the thecal sac raises the question of the utility of immediate postoperative MRI.

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Andrew S. Little, Kristina Chapple, Heidi Jahnke and William L. White

Object

An increasingly important measure in the health care field is utilization of hospital resources, particularly in the context of emerging surgical techniques. Despite the recent widespread adoption of the endoscopic transsphenoidal approach for pituitary lesion surgery, the health care resources utilized with this approach have not been compared with those utilized with the traditional microscopic approach. The purpose of this study was to determine the drivers of resource utilization by comparing hospital charges for patients with pituitary tumors who had undergone either endoscopic or microscopic transsphenoidal surgery.

Methods

A complete accounting of all hospital charges for 166 patients prospectively enrolled in a surgical quality-of-life study at a single pituitary center during October 2011–June 2013 was undertaken. Patients were assigned to surgical technique group according to surgeon preference and then managed according to a standard postoperative institutional set of orders. Individual line-item charges were assigned to categories (such as pharmacy, imaging, surgical, laboratory, room, pathology, and recovery unit), and univariate and multivariate statistical analyses were conducted.

Results

Of the 166 patients, 99 underwent microscopic surgery and 67 underwent endoscopic surgery. Baseline demographic descriptors and tumor characteristics did not differ significantly. Mean total hospital charges were $74,703 ± $15,142 and $72,311 ± $16,576 for microscopic and endoscopic surgery patients, respectively (p = 0.33). Furthermore, other than for pathology, charge categories did not differ significantly between groups. A 2-step multivariate regression model revealed that length of stay was the most influential variable, followed by a diagnosis of Cushing's disease, and then by endoscopic surgical technique. The model accounts for 42% of the variance in hospital charges.

Conclusions

Study findings suggest that adoption of the endoscopic transsphenoidal technique for pituitary lesions does not adversely affect utilization of resources for inpatients. The primary drivers of hospital charges, in order of importance, were length of stay, a diagnosis of Cushing's disease, and, to a lesser extent, use of the endoscopic technique. This study also highlights the influence of individual surgeon practice patterns on resource utilization.