Patrick J. Connolly

Anterior cervical fusion : Outcome analysis of patients fused with and without anterior cervical plates

The purpose of this study was to assess the role of the anterior cervical plate in the treatment of cervical spondylosis. Forty-three patients surgically treated for cervical spondylosis were reviewed. The technique for discectomy and fusion was the same for both groups (Smith-Robinson with autologous iliac crest bone graft). Group I consisted of 25 consecutive patients treated with anterior cervical discectomy, autograft fusion, and anterior cervical plate fixation (Morscher titanium hollow screw plate system). Group II consisted of 18 consecutive patients treated without plate fixation. The overall clinical results in this study were not improved with the use of anterior cervical plate fixation (Fishers exact test, p > 0.05). The fusion rate of one-level cervical fusions was not improved with anterior cervical plate fixation (Fishers exact test, p > 0.05). The overall graft complication rate (pseudoarthrosis plus delayed union plus graft collapse) in multilevel fusions was decreased with anterior cervical plate fixation (Fishers exact test, p < 0.01). The cost effectiveness and risk versus benefit of anterior cervical plate fixation in the surgical treatment of cervical spondylosis require further investigation.

Airway complications associated with surgery on the anterior cervical spine.

Study Design. Retrospective chart review of 311 anterior cervical procedures. Objectives. To assess the incidence and variables that predispose to an airway complication in a large series of anterior cervical surgical procedures. Summary of Background Data. A rare but potentially lethal complication after anterior cervical spine surgery is respiratory compromise and airway obstruction. Some risk factors are thought to include two-level corpectomy in myelopathic patients with a history of heavy smoking and asthma. No previous study in the literature has been directed at examining the factors specifically related to airway complications after anterior cervical spine surgery. Methods. Each chart was examined for patient characteristics and pathology, anesthetic parameters and problems, operative procedure, and postoperative course and management. Statistical analysis was performed. Results. Nineteen patients (6.1%) had an airway complication and six (1.9%) required reintubation. One patient died. Symptoms developed on average 36 hours postoperatively. All complications except for two were attributable to pharyngeal edema. Variables that were found to be statistically associated with an airway complication (P < 0.05) were exposing more than three vertebral bodies, a blood loss >300 mL, exposures involving C2, C3, or C4, and an operative time >5 hours. A history of myelopathy, spinal cord injury, pulmonary problems, smoking, anesthetic risk factors, and the absence of a drain did not correlate with an airway complication. Conclusions. Patients with prolonged procedures (i.e., >5 hours) exposing more than three vertebral levels that include C2, C3, or C4 with more than 300-mL blood loss should be watched carefully for respiratory insufficiency.

Recurrent Laryngeal Nerve Injury With Anterior Cervical Spine Surgery: Risk With Laterality of Surgical Approach

Study Design. A detailed review of anterior cervical fusion procedures from a university-based spine specialty service was completed. Noted were the laterality of approach, number of levels, discectomy or corpectomy, use of instrumentation, and cases of reoperation. Objectives. The primary purpose of the study is to determine whether there is in fact a greater risk of recurrent laryngeal nerve (RLN) injury with approach on the right or left side. Also evaluated is the risk with corpectomy, reoperative procedures, and instrumentation. Background. Anatomic considerations have been used as justification to determine the side of surgical approach. However, few clinical studies have delineated the side of surgical approach in their results. Methods. A total of 328 anterior cervical spine fusion procedures completed between 1989 and 1999 were reviewed. All speech changes reported were noted throughout follow-up. Results. There were 187 anterior discectomy and 141 corpectomy procedures. There were 21 reoperative anterior fusions. There were 173 procedures completed from the right side and 155 from the left. There were nine patients documented to have dysphonia after surgery. Five had a left-sided approach and four had a right-sided approach. Conclusions. The incidence of RLN symptoms after surgery was 2.7% (9 of 328). The incidence of RLN symptoms was 2.1% with anterior cervical discectomy, 3.5% with corpectomy (5 of 141), 3% with instrumentation (8 of 237), and 9.5% with reoperative anterior surgery (2 of 21). There was a significant increase in the rate of injury with reoperative anterior fusion. There was no association between the side of approach and the incidence of RLN symptoms.

Cerebral Venous Thrombosis in Children

Cerebral venous thrombosis is an important cause of stroke in children. Understanding the natural history of the disease is essential for rational application of new interventions. We retrospectively identified 31 children with cerebral venous thrombosis confirmed by head computed tomography (4 patients) or by magnetic resonance imaging (27 patients). Risk factors, clinical and radiographic features, and neurologic outcomes were analyzed. There were 21 males and 10 females aged 1 day to 13 years (median 14 days). Nineteen (61%) were neonates. The most common risk factors included mastoiditis, persistent pulmonary hypertension, cardiac malformation, and dehydration. The chief clinical features were seizures, fever, respiratory distress, and lethargy. Fifteen patients had infarctions (8 hemorrhagic, 7 ischemic). Protein C and antithrombin III deficiency were the most common coagulopathies among 14 tested patients. On discharge, 11 patients were normal, 17 had residual deficits, and 2 patients died. Twenty-seven patients were followed from 1 month to 12 years (mean 22 months). At follow-up, 11 patients were normal, and 13 patients had development delay. One had residual hemiparesis and cortical visual impairment. Two had other deficits. Neonatal cerebral venous thrombosis is probably more common than previously thought, and outcomes are worse in this group. All children with cerebral venous thrombosis should be tested for coagulation disorders. (J Child Neurol 2001;16:574-580).

Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine.

We evaluated eighty-three patients in whom adolescent idiopathic scoliosis had been treated with a posterior spinal arthrodesis and Harrington instrumentation extending to the second, third, fourth, or fifth lumbar vertebra. All eighty-three patients completed a questionnaire, and fifty-five patients were also examined clinically and roentgenographically at a follow-up evaluation at an average of twelve years (range, ten to sixteen years). Twelve patients had a type-I curve; twenty-six, a type-II curve; sixteen, a type-III curve; and one, a type-IV curve, according to the classification of King et al. The preoperative Cobb angle of the primary curve averaged 60 degrees and ranged from 40 to 100 degrees. The curve was an average of 35 degrees (range, 15 to 65 degrees) at the most recent follow-up evaluation. Functional assessment with use of information from the questionnaire revealed an average spine score of 81 points (range, 18 to 99 points). On the basis of the score, thirty-five patients were considered to have had an excellent result; twenty, a good result; thirteen, a fair result; and fifteen, a poor result. Sixty-three (76 per cent) of the eighty-three patients had low-back pain compared with thirty (50 per cent) of sixty individuals who served as a control group. This difference was significant (p < 0.001; chi-square test). Eighteen patients (22 per cent) needed additional spinal procedures. Fourteen patients (17 per cent) did not think that the goals of the initial operation had been accomplished.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of strain, novelty, and NMDA blockade on auditory-evoked potentials in mice.

People with schizophrenia exhibit impaired ability to modify electroencephalographic event-related potential (ERP) responses to novel stimuli. These deficits serve as a window into the abnormalities of neuronal organization and function and are thought to reflect a component of genetic vulnerability for schizophrenia. We describe differences among inbred mouse strains for ERPs following a novelty detection paradigm, as a model for genetic contributions to disease vulnerability. Auditory-evoked potentials were recorded during an auditory oddball task in nonanesthetized C57BL/6J, C3H/HeJ, and DBA/2J mice prior to and following ketamine (10 mg/kg). Stimuli consisted of 80 sets of 24 standard tones followed by one novel tone. Principal component analysis yielded four temporal components that contribute to the auditory ERP responses to standard and novel stimuli. Two principal components that varied between standard and novel stimuli also differed among inbred mouse strains. Post hoc analyses indicate that strain effects on novelty detection are due to a significant difference between the response to novel and standard tones in C3H/HeJ mice that is absent in the other two strains. Inbred strains of mice vary in their ability to perform neuronal detection of change in the auditory environment. The ability to model novelty detection deficits in mice will aid in identifying genetic contributions to abnormal neuronal organization in people with schizophrenia.

Characteristics of unicortical and bicortical lateral mass screws in the cervical spine

STUDY DESIGN A biomechanical study evaluating the safety and efficacy of unicortical versus bicortical lateral mass screws in the cervical spine. OBJECTIVES To analyze the safety, pullout strength and radiographic characteristics of unicortical and bicortical screws placed in cadaveric spines and to evaluate the influence of level of training on the positioning of these screws. SUMMARY OF BACKGROUND DATA Lateral mass plating for posterior cervical spine fusion is an effective method for the treatment of traumatic and degenerative instability. The initial description of the technique included bicortical screw purchase. The added benefit of bicortical purchase must be weighed against the increased risk of injury to nerve roots and the vertebral artery. METHODS In 21 cadaveric spines (mean age 78.9 years), 3.5-mm anterior oblique lateral mass screws were placed bilaterally from C3 to C6 (n = 168) using a modification of the Magerl technique. In the right side (unicortical) only 14-mm screws (effective length of 11 mm) were used, whereas on the left side, bicortical purchase was obtained. All screws were evaluated clinically and radiographically for safety and zone placement. Pullout force was determined for all screws. RESULTS Most screws (92.8%) were rated satisfactory. There were no injuries to the spinal cord. On the right side (14 mm) 98.9% of the screws were satisfactory, and on the left side (bicortical) 68.1% were satisfactory. There was a 5.8% incidence of direct artery injury (compression of vessel wall) and a 17.4% incidence of direct nerve root injury by the bicortical screws. There were no direct injuries with the unicortical screws. Most of the direct-injury bicortical screws were placed by the surgeon with the least experience. The mean pullout force for all screws was 542.9 +/- 296.6 N. There was no statistically significant difference between the pullout force for unicortical (519.9 +/- 286.9 N) and bicortical (565.2 +/- 306 N) screws (P < 0.05). There were no significant differences in pullout strengths in association with zone placement. CONCLUSIONS Fourteen-millimeter lateral mass screws (effective length, 11 mm) placed in a superolateral trajectory in the adult cervical spine provide an equivalent strength with a much lower risk of injury than the longer bicortical screws placed in a similar orientation.

Does Long-Term Itraconazole Prophylaxis Result in In Vitro Azole Resistance in Mucosal Candida albicans Isolates from Persons with Advanced Human Immunodeficiency Virus Infection?

ABSTRACT The effects of prolonged itraconazole exposure on the susceptibility of Candida albicans isolates to itraconazole and fluconazole have not been well characterized. A recent placebo-controlled study of long-term itraconazole antifungal prophylaxis in persons with advanced human immunodeficiency virus infection afforded the opportunity to address this question. MucosalCandida sp. isolates were obtained from subjects who developed oropharyngeal or esophageal candidiasis, and in vitro susceptibilities of the last isolate obtained at removal from the study as a prophylaxis failure were compared in itraconazole and placebo recipients. More subjects in the placebo group (74 of 146 [51%]) than in the itraconazole group (51 of 149 [34%]) developed mucosal candidiasis (P = 0.004). A total of 112 isolates were recovered from 56 of the 74 (76%) subjects with mucosal candidiasis assigned to the placebo group, compared to 97 isolates from 45 of the 51 (88%) subjects in the itraconazole group. C. albicansaccounted for 98% of isolates in the placebo group and 89% of isolates in the itraconazole group. The itraconazole MIC at which 50% of the isolates tested were inhibited (MIC50) for last-episode isolates from the itraconazole group was 0.125 μg/ml compared to 0.015 μg/ml for the placebo group subjects,P = 0.0001. The MIC50 of fluconazole for the last isolates from the itraconazole group was 1.5 μg/ml compared to 0.5 μg/ml for the placebo subjects (P = 0.005). A lower proportion of isolates recovered from subjects on itraconazole therapy were classified as susceptible to itraconazole (63%) compared to isolates from the placebo group (96%) (P = 0.001). Similarly, a lower proportion of C. albicans isolates from subjects on itraconazole therapy were susceptible to fluconazole (78%) compared to isolates from the placebo group (96%) (P= 0.01). Also, the proportion of isolates that were not fully susceptible to itraconazole or fluconazole was greater in patients assigned to the itraconazole group than the placebo group (itraconazole susceptibility, 37 and 4%, respectively (P = 0.001); fluconazole susceptibility, 23 and 4%, respectively (P = 0.01). In conclusion, long-term itraconazole prophylaxis in patients with AIDS is associated with reduction in susceptibility to itraconazole and cross-resistance to fluconazole.

Electromagnetic Field-Based Image-Guided Spine Surgery Part One : Results of a Cadaveric Study Evaluating Lumbar Pedicle Screw Placement

Study Design. Human cadaveric. Objectives. Compare the accuracy of electromagnetic field (EMF)-based image-guided lumbar pedicle screw insertion to conventional techniques using anatomic landmarks, and fluoroscopy. Background. Image-guided surgical systems that aid in spinal instrumentation seek to minimize radiation exposure and improve accuracy. EMF tracking-based image-guidance was developed in the hopes of eliminating line-of-sight restrictions seen with other systems. Materials and Methods. Sixteen fresh-frozen human cadavers were randomly allocated into three groups. Pedicle screws were inserted from L1 to L5 using only anatomic landmarks in group 1, fluoroscopy in group 2, and image-guidance in group 3. Insertion and total fluoroscopic time were recorded. Anatomic dissections were performed to assess screw placement. Results. Accuracy was 83%, 78%, and 95% for groups 1, 2, and 3, respectively. However, image-guided pedicle screw placement resulted in a 5% critical perforation rate whereas anatomic and fluoroscopic placement resulted in a 15% and 22% critical perforation rate, respectively. The average degree of perforation was 1.5 mm with image guidance, and 3.8 mm with fluoroscopic guidance (P < 0.05). Fluoroscopy time and insertion time per screw were not improved using image guidance. Conclusions. Our study has shown that when EMF tracking was used for image-guided lumbar pedicle screw placement, accuracy was improved and the incidence and degree of cortical perforations that may place neurovascular structures at risk was also reduced. Current system requirements for set-up and image acquisition, however, do add time to the procedure, and when factored in, do not yet result in a decrease in the use of fluoroscopy or screw insertion time.

Objective Measurement of Corneal Light Scattering after Excimer Laser Keratectomy

PURPOSE To obtain objective measurements of corneal light scattering after excimer laser keratectomy, and to evaluate the relation of light scattering to clinical haze grading and visual acuity. METHODS The authors measured best-corrected visual acuity, subjective clinical haze grade, and corneal light-scattering index in patients undergoing photorefractive keratectomy (PRK) (n=26), and phototherapeutic keratectomy (n=8), preoperatively and postoperatively at 1,3,6,9, and 12 months or later. Corneal light scattering was correlated with visual acuity and clinical haze grade. RESULTS Corneal light scattering increased after PRK and was reduced after phototherapeutic keratectomy. Corneal light scattering index showed a stronger positive correlation with logMAR visual acuity (r=0.57) than clinical haze grading (r=0.34). Corneal light-scattering index (P<0.05 at 1 and 3 months) and clinical haze grading (P<0.05 at 6, 9, and 12 months) were significantly higher in eyes undergoing PRK with ablation depths of more than 80 microns. CONCLUSIONS Excimer laser surgery affects corneal light scattering. Ablations with depths greater than 80 microns produce significantly higher levels of haze than those less than 80 microns. Objective measurement of corneal light scattering may be useful in monitoring the outcome of excimer keratectomy.