Gregory P. Lee

Anterior Cervical Discectomy and Fusion Associated Complications

Study Design. Retrospective review study with literature review. Objective. The goal of our current study is to raise awareness on complications associated with anterior cervical discectomy and fusion (ACDF) and their early detection and proper management. Summary of Background Data. It is known that ACDF constitutes one of the most commonly performed spinal procedures. Its outcome is quite satisfactory in the majority of cases. However, occasional complications can become troublesome, and in rare circumstances, catastrophic. Although there are several case reports describing such complications, their rate of occurrence is generally underreported, and data regarding their exact incidence in large clinical series are lacking. Meticulous knowledge of potential intraoperative and postoperative ACDF-related complications is of paramount importance so as to avoid them whenever possible, as well as to successfully and safely manage them when they are inevitable. Methods. In a retrospective study, 1015 patients undergoing first-time ACDF for cervical radiculopathy and/or myelopathy due to degenerative disc disease and/or cervical spondylosis were evaluated. A standard Smith-Robinson approach was used in all our patients, while an autologous or allograft was used, with or without a plate. Operative reports, hospital and outpatient clinic charts, and radiographic studies were reviewed for procedure-related complications. Mean follow-up time was 26.4 months. Results. The mortality rate in our current series was 0.1% (1 of 1015 patients, death occurred secondary to an esophageal perforation). Our overall morbidity rate was 19.3% (196 of 1015 patients). The most common complication was the development of isolated postoperative dysphagia, which observed in 9.5% of our patients. Postoperative hematoma occurred in 5.6%, but required surgical intervention in only 2.4% of our cases. Symptomatic recurrent laryngeal nerve palsy occurred in 3.1% of our cases. Dural penetration occurred in 0.5%, esophageal perforation in 0.3%, worsening of preexisting myelopathy in 0.2%, Horner’s syndrome in 0.1%, instrumentation backout in 0.1%, and superficial wound infection in 0.1% of our cases. Conclusion. Meticulous knowledge of the ACDF-associated complications allows for their proper management. Postoperative dysphagia, hematoma, and recurrent laryngeal nerve palsy were the most common complications in our series. Management of complications was successful in the vast majority of our cases.

Unilateral cerebral inactivation produces differential left/right heart rate responses

We studied heart rate following unilateral hemispheric inactivation by intracarotid amobarbital in 25 patients undergoing preoperative evaluation for epilepsy surgery. Heart rate increased after left hemisphere inactivation, but decreased following right hemisphere inactivation. The results are consistent with differential left/right cerebral hemispheric effects on autonomic function, and appear related to functional and anatomic asymmetries in both the central and peripheral nervous systems.

Cerebral language lateralization : evidence from intracarotid amobarbital testing

Cerebral language lateralization was investigated in 103 patients undergoing intracarotid amobarbital testing as part of their diagnostic work-up for epilepsy surgery. Inclusion criteria included adequate bilateral intracarotid amobarbital studies and no radiologic lesion in areas other than the temporal lobe. Language was evaluated with respect to strict presence or absence of language representation, in which a patient was considered to have bilateral language despite potentially having asymmetric language representation, and with respect to forced relative hemispheric dominance, in which a single side could be considered dominant despite bilateral language representation. Seventy-nine patients displayed exclusive left hemisphere language representation, two patients showed exclusive right hemisphere language representation, and 22 patients had language represented in each hemisphere. In the 22 patients with bilateral language, an asymmetry was present in 17 cases (13 L greater than R, 4 R greater than L). These data indicate that language restricted only to the right hemisphere is rare, and that in the absence of purely left hemisphere language, most patients exhibit bilateral representation. Previously reported incidence of exclusive right hemisphere language may be an artifact of dichotomizing a continuous variable.

Determinants of quality of life in epilepsy.

Although depression is associated with diminished quality of life (QOL) in epilepsy patients, the relative contributions of epilepsy-specific concerns, as well as clinical and cognitive variables of QOL, have not been simultaneously investigated. A comprehensive neuropsychological test battery including the Beck Depression Inventory (BDI), Epilepsy Foundation of Americas (EFA) Concerns Index, MMPI-2, QOLIE-89, WAIS-III, and Selective Reminding was administered to 115 epilepsy surgery candidates with normal Full Scale IQs. Linear regression analyses were performed to identify significant predictor combinations of QOLIE-89 total score. Regression analysis demonstrated that depressive symptomatology, whether reflected by the BDI (R2=0.45) or Depression scale of the MMPI-2 (R2=0.36), was a robust individual QOL predictor. Seizure Worry from the EFA Concerns Index was nearly as effective as the BDI in predicting QOLIE-89 (R2=0.42). When the BDI and EFA Concerns Index were combined into the same regression, both factors continued to contribute significantly to the QOLIE-89 total score, with both variables accounting for 61% of the variance. Although patients who developed their seizures at an older age had poorer QOL and patients with higher educational levels reported higher QOL, neither factor was related to QOL after accounting for the effects of psychological variables and epilepsy-related concerns. Although quality of life has multiple determinants, symptoms of depression and seizure worry are the most important factors affecting QOL in patients with intractable epilepsy.

Wada memory testing and hippocampal volume measurements in the evaluation for temporal lobectomy.

We examined the relationship of Wada memory performance and MRI hippocampal volume measurements to laterality of ultimate seizure localization in 20 patients with complex partial seizures who later underwent temporal lobectomy. Discriminant function analysis employing both Wada memory test asymmetries and hippocampal volume asymmetries correctly classified 100% of the patients into left and right temporal lobe groups. Wada memory asymmetries alone correctly classified 90% of the sample (80% of the sample when the discriminant function included all patients except the one being classified), and hippocampal volume asymmetries alone correctly classified 90% of the patients. A significant correlation was present between Wada memory asymmetries and hippocampal volume asymmetries (r = 0.78), indicating that structural evidence of reduced hippocampal volume has a functional correlate reflected by Wada memory performance. These data suggest that the combination of functional and structural measures is of value in the preoperative evaluation for epilepsy surgery.

Neural Substrates of Emotion As Revealed by Functional Magnetic Resonance Imaging

Objectives:To examine the brain circuitry involved in emotional experience and determine whether the cerebral hemispheres are specialized for positive and negative emotional experience. Background:Recent research has provided a preliminary sketch of the neurologic underpinnings of emotional processing involving specialized contributions of limbic and cortical brain regions. Electrophysiologic, functional imaging, and Wada test data have suggested positive, approach-related emotions are associated with left cerebral hemisphere regions, whereas negative, withdrawal-related emotions appear to be more aligned with right hemisphere mechanisms. Method:These emotional–neural associations were investigated using functional magnetic resonance imaging in 10 healthy controls with 20 positively and 20 negatively valenced pictures from the International Affective Picture System in a counterbalanced order. Pictures were viewed within a 1.5 Telsa scanner through computerized video goggles. Results:Emotional pictures resulted in significantly increased blood flow bilaterally in the mesial frontal lobe/anterior cingulate gyrus, dorsolateral frontal lobe, amygdala/anterior temporal regions, and cerebellum. Negative emotional pictures resulted in greater activation of the right hemisphere, and positive pictures caused greater activation of the left hemisphere. Conclusions:Results are consistent with theories emphasizing the importance of circuitry linking subcortical structures with mesial temporal, anterior cingulate, and frontal lobe regions in emotion and with the valence model of emotion that posits lateralized cerebral specialization for positive and negative emotional experience.

The intracarotid amobarbital procedure as a predictor of memory failure following unilateral temporal lobectomy

We investigated the efficacy of the intracarotid amobarbital procedure to accurately predict post-temporal lobectomy anterograde amnesia. We presented items at 2 separate times during amobarbital assessment; both early and late item recall were decreased during the injection contralateral to seizure onset indicating sensitivity to bilateral temporal lobe dysfunction. Ten patients for whom follow-up neuropsychological assessment was available failed either the early or late item recognition portions of their amobarbital evaluation ipsilateral to seizure onset, but had hippocampus included in the temporal lobectomy by virtue of satisfactory performance on other tests of hippocampal function. None of these 10 patients displayed postoperative anterograde amnesia, although there was a reduction in material-specific memory in some patients. These results indicate that relying solely on amobarbital memory testing to assess the functional ability of the contralateral temporal lobe to sustain global memory prior to temporal lobectomy may needlessly exclude patients from a viable therapeutic option.

Wada memory asymmetries predict verbal memory decline after anterior temporal lobectomy

We examined Wada memory and neuropsychological memory function in 34 nonlesional patients who underwent anterior temporal lobectomy (ATL) and who were seizure free at 1-year follow-up. Patients who displayed a decline on verbal memory measures that exceeded 1 SD after left ATL had significantly smaller left/right Wada memory asymmetries than left ATL patients without a significant verbal memory decline. When Wada memory asymmetries were used to predict verbal memory decline after left ATL in individual patients, similar statistically significant effects were present. No significant relationship between Wada memory and postoperative memory was present in right ATL patients, and postoperative memory function was not related to Wada memory performance after either left hemisphere or right hemisphere injection alone. We conclude that Wada memory asymmetries provide one measure of the risk to material-specific decline in verbal memory after left ATL.

Construct validity of material-specific memory measures following unilateral temporal lobe ablations.

Material-specific memory test performance of 18 left (LTL), and 11 right (RTL), unilateral temporal lobectomy patients was assessed pre- and 1 wk postsurgery. Selective Reminding and Serial Digit Learning tests were the verbal, and Complex Figure and Form Sequence Learning tests were the nonverbal, learning measures. Reasons for the difficulty in finding «pure» measures of visual learning are discussed, and suggestions for future nonverbal memory test development are presented

Psychometric construction of the Rey-Osterrieth complex figure : methodological considerations and interrater reliability

Formal scoring criteria for the standard 18 elements of the Rey-Osterrieth Complex Figure were developed and applied to reproductions of 87 healthy young adults. In addition, the effects of immediate recall on delayed performance was investigated. Results indicate (a) the formal scoring criteria can be reliably applied by independent raters; (b) 30-minute recall is significantly higher if immediate reproduction is included compared to 30-minute delay performance without immediate recall; (c) significantly fewer qualitative scoring errors are present at the 30-minute delay if immediate memory is previously assessed; and (d) in addition to an absence of decay over a 30-minute delay, performance significantly improves over this interval. These findings underscore the caution that must be exercised when making specific inferences from test scores alone based upon measures that were obtained in a variety of contexts employing unspecified scoring criteria.