Hugh F. Smisson

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.

Results of long-term follow-up in patients undergoing anterior screw fixation for type II and rostral type III odontoid fractures.

Study Design. Retrospective analysis of the fusion rate of a group of 38 patients having undergone anterior screw fixation for type II and “shallow” type III odontoid fractures. Objective. To determine primarily the long-term fusion rate after anterior screw fixation and to study the clinical characteristics of patients that have a statistically significant or nonsignificant influence on successful outcome. Summary of Background Data. Long-term outcome of anterior screw fixation for odontoid fractures has been evaluated in very few studies. This information should be critical for further establishing this technique as a major therapeutic strategy for these cases. Methods. Thirty-eight patients, 25 males and 13 females (with mean age 48.4 ± 0.4 years), with type II and rostral type III odontoid fractures, underwent anterior cannulated screw fixation during a 62-month period. Radiologic examination of the cervical spine with plain radiographs was performed at 6 weeks, and 2, 6, 12, and 24 months, while computerized tomography of the upper cervical spine (C1–C3) was obtained at 6 months after surgery. Follow-up was available for 31 patients, and the follow-up time ranged from 39 to 87 months (mean 58.4). Results. Radiographic evaluation of the follow-up group showed satisfactory bony fusion and no evidence of abnormal movement at the fracture site in 27 (87.1%) patients. Pseudarthrosis developed in 4 (12.9%) patients; however, 3 (9.6%) of them without instability and 1 (3.2%) with instability. One (3.2%) patient had an instrumentation failure without instability. Conclusions. In our series, anterior odontoid screw fixation comprised a safe therapeutic modality with high stability and low mechanical failure rates during short-term and long-term follow-up.

In vivo Proton Magnetic Resonance Spectroscopy of Brain Tumors

The ability of magnetic resonance spectroscopy (MRS) to differentiate neoplastic brain cells and their metabolic and structural characteristics is evaluated. We examined 120 patients with brain tumors using a 1.5-tesla MRI unit and MRS. The peak areas of N-acetyl-aspartate (NAA), phosphocreatine-creatine (Pcr-Cr), choline-containing compounds (Cho), lactate, lipids, myoinositol, amino acids and the ratios of NAA/Pcr-Cr, NAA/Cho and Cho/Pcr-Cr were calculated by a standard integral algorithm. In normal brain tissue, the following metabolites were identified: NAA at 2.0 ppm, Pcr-Cr at 3.0 ppm and Cho at 3.2 ppm. The different concentrations of the metabolites examined and their role in the biochemical profile of different types of tumors are discussed. The confidence interval of the MRS versus pathology was between 0.9 and 0.954, while it was between 0.52 and 0.631 for MRI versus pathology. The Cho/Pcr-Cr ratio is a very important malignancy marker for histologic tumor grading of astrocytomas. The greater this ratio, the higher the grade of the astrocytoma. NAA/Pcr-Cr together with Cho/Pcr-Cr help specify the presence or absence of a neoplasm. Proton MRS is a useful and promising diagnostic modality not only in diagnosing but also in grading solid brain tumors.

Intraventricular administration of rt-PA in patients with intraventricular hemorrhage.

Objective: Intraventricular hemorrhage (IVH) represents a clinicopathologic entity with a dismal prognosis. The associated mortality rate has been reported as high as 80%; the morbidity is also quite high. The use of various fibrinolytic agents (streptokinase, urokinase, and recombinant tissue-type plasminogen activator [rt-PA]) has been reported in a small number of clinical series with a very limited number of participants, yielding significant variability regarding inclusion criteria, treatment protocol, and outcome analysis. Methods: In our prospective study, we report our experience using rt-PA in 21 patients with IVH. Patients with IVH of aneurysmal or arteriovenous malformation origin were excluded. Intraventricular administration of rt-PA was initiated within 24 hours after the ictal event (dose, 3 mg every 24 hours) through a ventricular catheter. The patients’ intracranial and cerebral perfusion pressures, cerebrospinal fluid (CSF) cell count, and head CT scans with emphasis to frontal horn dimension and inner cranium diameter at the same level ratio were collected and analyzed. Results: Good outcome was observed in 47.5% of our patients, whereas 28.5% died and 24.0% survived with severe disability. The development of rt-PA–associated complications was as follows: new hemorrhage in 19%, infection in 14.3%, and CSF pleocytosis in 100% of patients. Permanent CSF shunt was required in 40%. The intermediate (3-month) follow up of our survivors showed no significant outcome changes compared with the immediate (1-month) follow up. Conclusions: Intraventricular administration of rt-PA appears to be beneficial in cases of IVH even though it is occasionally associated with serious complications. Further multi-institutional studies are required for validating this treatment modality and standardizing its parameters.

Review of the literature regarding the relationship of rebleeding and external ventricular drainage in patients with subarachnoid hemorrhage of aneurysmal origin

Acute hydrocephalus is a well-documented complication of subarachnoid hemorrhage. The insertion of external ventricular drainage (EVD) has been the standard of care in the management of this complication, aiming primarily at immediate improvement of the clinical condition of these patients, making them more suitable candidates for surgical or endovascular intervention. In our current communication, we review the pertinent literature regarding the relationship of rebleeding and EVD. Several studies have implicated a significantly increased risk of rebleeding in patients with EVD, compared with patients without it. Abrupt lowering of the intracranial pressure could lead to rebleeding due to decreased transmural pressure or removal of the clot sealing the previously ruptured aneurysm. However, a variety of parameters that could affect the rebleeding rate, such as the timing of surgery, the timing and duration of drainage, the size of the aneurysm, as well as the severity of the initial hemorrhage, do not seem to have been adequately explored in the majority of these studies. In addition, a number of clinical trials have failed to provide evidence for the negative role of EVD in the development of rebleeding. Conclusively, further long-term multi-center studies are required in order to establish the exact nature of the relationship between EVD and rebleeding after aneurysmal subarachnoid hemorrhage.

Quantitative Estimation of the Recurrent Laryngeal Nerve Irritation by Employing Spontaneous Intraoperative Electromyographic Monitoring During Anterior Cervical Discectomy and Fusion

Study Design Prospective, clinical study. Objective The objective of our study was to evaluate the role of laryngeal intraoperative electromyography (IEMG) in predicting the development of postoperative recurrent laryngeal nerve (RLN) palsy in patients undergoing anterior cervical discectomy and fusion (ACDF). We also attempted to develop a method to quantify the total IEMG irritation of the RLN. Summary of Background Data RLN injury has been recognized as the most common ACDF-associated neurologic injury. It has been postulated, that the employment of laryngeal IEMG may identify the operative events leading to RLN injury and subsequent postoperative palsy. Methods Laryngeal IEMG monitoring was performed in 298 patients undergoing ACDF. Preexistent baseline EMG activity, amplitude, and duration of IEMG activity were recorded. The total amount of RLN irritation was expressed as an Irritation Score (IS) applying a specially designed mathematical equation incorporating the amplitude, the duration, and the presence of any baseline EMG irritation. The relationship of IEMG activity with parameters such as the number of operative levels, the duration of the procedure, the presence of any previous neck surgeries, and the type of the used retractor was examined. Results IEMG activity was recorded in 14.4% of our patients. Postoperative RLN injury occurred in 2.3% of our patients. The sensitivity of IEMG was 100%, the specificity 87%, the positive predictive value 16%, and its negative predictive value 97%. The calculated IS ranged between 0.28 and 3.47 (mean IS: 2.09). Significantly increased IEMG activity was found in patients with previous surgical intervention, patients undergoing multilevel procedures, long-lasting procedures, and cases in which self-retained retractors were used. Likewise, significantly increased IS were observed in patients with previous surgeries and in cases where self-retained retractors were used. Conclusions Our study indicates that laryngeal IEMG is a high-sensitivity modality that can provide real-time information and can potentially minimize the risk of operative RLN injury.

Surgical treatment of acute type II and rostral type III odontoid fractures managed by anterior screw fixation.

Objectives: In the present study, the authors comment on their experience with anterior odontoid screw fixation in the management of odontoid fractures, in an attempt to further assess the safety and the efficacy of this procedure. Materials and Methods: A retrospective analysis of 50 consecutive patients with reducible type II or rostral type III odontoid fractures, operated at our hospital with anterior odontoid screw fixation. Radiographic bony fusion, complications, and clinical outcome were evaluated. Results: Solid bony fusion was evident in 38 (90.5%) of the patients. One mechanical instrumentation-related complication occurred, without clinical significance. No other major complications related to the procedure were noted. A satisfactory range of motion in the cervical spine was observed in all patients. Conclusions: Anterior odontoid screw fixation is a safe and effective procedure for the treatment of type II and rostral type III odontoid fractures. Compliance to the specific indications and contraindications of this operation is crucial for optimal outcome.

C1-C2 Transarticular screw fixation for atlantoaxial instability

Objectives: The atlantoaxial segment of the cervical spine is commonly destabilized in a variety of disorders. Transarticular screw fixation of the C1-C2 joint has been proposed as a biomechanically superior therapeutic modality. The authors present their experience with this technique. Methods: A retrospective analysis of 23 patients treated with this technique was performed. The mean follow-up period was 39.5 ± 0.1 months. Results: Mean duration of hospitalization was 3.4 ± 0.1 days (range, 2 to 11 days). No intraoperative or early postoperative complications were detected. Four patients (17.4%) had postoperative complications unrelated to the primary procedure. The position of the screw was judged as satisfactory in 21 patients (91.3%). Two patients (8.7%) with suboptimal positioning of the screws were neurologically intact but needed no reoperation. Solid osseous fusion was detected in 19 patients (82.6%). Conclusions: Transarticular C1-C2 screw fixation appears to be a safe and surgically reliable technique. Criteria for its application and refinements in its technical considerations continue to advance its clinically versatile therapeutic potential.

Results and Complications from the Use of a Frameless Stereotactic Microscopic Navigator System

We present a series of 21 patients, 12 males and 9 females, aged 41–76 years, with the preoperative diagnosis of a brain tumor. Both preoperatively and postoperatively, all of our patients underwent either a brain computed tomography (CT) or magnetic resonance imaging (MRI). All the radiographic studies were taped and loaded preoperatively in the Stereotactic Microscopic Navigator (SMN) workstation (Zeiss, Germany). The mean duration of this procedure was 25 ± 6 min. All our patients were operated on in our institute with the use of the SMN system. The specificity of tumor localization using CT scan was 2.20 ± 0.25 mm and for the MRI scan 2.6 ± 0.25 mm. As assessed by postoperative radiographic studies, total gross tumor resection was possible in 20 patients (95.23%). No major intraoperative or early postoperative complications were noted in our series. We believe that the SMN system is a safe, well-tolerated by the patients and simple method with extremely high accuracy and specificity.

Does intraoperative electromyographic monitoring in lumbar microdiscectomy correlate with postoperative pain

Objectives: Our objective was to correlate the findings of intraoperative electromyographic (EMG) monitoring with immediate postoperative pain in patients undergoing lumbar microdiscectomy. Methods: A total of 112 patients undergoing de novo lumbar microdiscectomy were prospectively randomized into a control group (n = 45) and a study group (n = 67) in which intraoperative EMG monitoring was used. Postoperative pain and postoperative narcotic consumption were recorded for each patient. Results: The presence or absence of EMG monitoring did not influence the level of reported pain in any anatomic area. In the monitored group, the degree of recorded nerve root irritation did not correlate with reported pain or postoperative narcotic consumption. The level of back pain was found to be significantly higher than the level of hip and calf pain (P < 0.0001). Conclusions: In our study no correlation was found between intraoperative EMG findings and immediate postoperative pain.