Marjorie C. Wang

Complications and mortality associated with cervical spine surgery for degenerative disease in the United States.

Study Design. Retrospective cohort. Objectives. To describe the incidence of complications and mortality associated with surgery for degenerative disease of the cervical spine using population-based data. To evaluate the associations between complications and mortality and age, primary diagnosis and type of surgical procedure. Summary of Background Data. Recent studies have shown an increase in the number of cervical spine surgeries performed for degenerative disease in the United States. However, the associations between complications and mortality and age, primary diagnosis and type of surgical procedure are not well described using population-based data. Methods. We created an algorithm defining degenerative cervical spine disease and associated complications using the International Classification of Diseases-ninth revision Clinical Modification codes. Using the Nationwide Inpatient Sample, we determined the primary diagnoses, surgical procedures, and associated in-hospital complications and mortality from 1992 to 2001. Results. From 1992 to 2001, the Nationwide Inpatient Sample included an estimated 932,009 (0.3%) hospital discharges associated with cervical spine surgery for degenerative disease. The majority of admissions were for herniated disc (56%) and cervical spondylosis with myelopathy (19%). Complications and mortality were more common in the elderly, and after posterior fusions or surgical procedures associated with a primary diagnosis of cervical spondylosis with myelopathy. Conclusions. There are significant differences in outcome associated with age, primary diagnosis, and type of surgical procedure. Administrative databases may underestimate the incidence of complications, but these population-based studies may provide information for comparison with surgical case series and help evaluate rare or severe complications.

Trends and Variations in Cervical Spine Surgery in the United States: Medicare Beneficiaries, 1992 to 2005

Study Design. Retrospective cohort. Objective. To describe population-based trends and variations in surgery for degenerative changes of the cervical spine among Medicare beneficiaries, 1992 to 2005. Summary of Background Data. Degenerative changes of the cervical spine are seen radiographically in over half of the population aged 55 years or greater, and rates of cervical spine surgery have increased over time. Prior studies examined anterior cervical discectomy and fusion procedures in the general population up to 1999, and showed regional variations in care, with the highest rates in the South. The purpose of this study is to explore population-based trends and variations in surgery for degenerative changes of the cervical spine in the elderly. Methods. From 1992 to 2005, hospital admissions associated with surgery for degenerative changes of the cervical spine were selected from Medicare Part A using ICD9 CM codes. We excluded beneficiaries under 65 years of age, in a capitated health plan, or enrolled for Social Security Disability Income. Diagnosis and type of surgery were defined using ICD9 CM codes. Rates were directly adjusted to age, sex, and race of 2005 Medicare beneficiaries. Results. Of 156,820 qualifying admissions, 52% were men, 88% were white, and 41% were aged 65 to 69 years. The most common primary diagnosis and procedure were cervical spondylosis with myelopathy (36%) and fusion (70%); of the fusions, 58% were anterior. Rates of cervical fusions rose from 1992 to 2005 even after adjustment for age, sex, and race (14.7 to 45 cervical fusions/100,000 beneficiaries). Rates of cervical fusions varied by geographic location, with the highest rates in the Northwest and South Central regions. In 2005, the highest rate of cervical fusions was 140/100,000 beneficiaries in Idaho, compared with 4/100,000 beneficiaries in Washington, DC. Conclusion. In the elderly, adjusted rates of cervical spine fusions rose 206% from 1992 to 2005. Marked geographic variation was noted. Future studies should evaluatethe efficacy and complications associated with these procedures in the elderly, and better define surgical indications and patient outcome.

The diagnostic accuracy of computed tomography angiography for traumatic or atherosclerotic lesions of the carotid and vertebral arteries: a systematic review

INTRODUCTION Helical computed tomography angiography (CTA) has become an established technique for evaluating atherosclerosis of the cerebrovascular arteries. However, the role of CTA in penetrating and blunt trauma to the carotid and vertebral arteries is not well defined. We conducted a systematic literature review to determine the diagnostic accuracy of CTA for atherosclerotic, penetrating and blunt lesions in the carotid and vertebral arteries. METHODS We searched MEDLINE and EMBASE databases to identify studies evaluating the diagnostic accuracy of CTA of the carotid and vertebral arteries published between January 1, 1992 and December 31, 2002. Two reviewers independently assessed abstracts and full text to determine study eligibility. Information on methodological quality, imaging technique and diagnostic accuracy was abstracted from all eligible studies by three independent reviewers. We pooled sensitivity and specificity data from diagnostic accuracy studies of high methodological quality. RESULTS Forty-three articles met the inclusion criteria and were included in the review. Thirty studies examined atherosclerotic disease, two blunt trauma, two penetrating trauma and nine examined patients with other pathology. Pooled data from 15 higher quality studies demonstrated that CTA had a sensitivity of 95% (91-97% CI) for detecting severe (>70%) atherosclerotic stenosis of the carotid artery. The specificity of CTA for severe stenosis was also high 98% (96-99% CI). CTA remained a sensitive technique (95%; 93-97% CI) when the criterion for a positive result is relaxed to moderate or greater (>30%) stenosis. Two studies raised concerns about the use of CTA in the blunt trauma setting, suggesting that CTA may not be sensitive for detecting small intimal injuries, although both of these studies used older technologies for either obtaining or viewing images. Conversely, two penetrating trauma studies concluded that the sensitivity of CTA was high. CONCLUSIONS Our findings demonstrate that CTA is both a sensitive and specific imaging technique for identifying severe atherosclerotic stenosis and occlusion of the carotid arteries. However, there is currently not enough high quality evidence to accurately estimate the sensitivity and specificity of CTA in the setting of blunt or penetrating trauma.

The use of repeated head computed tomography in pediatric blunt head trauma: Factors predicting new and worsening brain injury

Objective: Opinion is divided on the value of repeat head computed tomography for guiding clinical management of pediatric patients with blunt head trauma. This study describes the prevalence of worsening brain injury on repeat computed tomography, predictors of worsening computed tomography findings, and the frequency of neurosurgical intervention after the repeat computed tomography. Design: Retrospective cohort study. Setting: All patients were admitted to a level I pediatric trauma center between 1994 and 2003. Patients: Children <15 yrs old with two or more head computed tomographies following hospital admission for blunt head trauma. Interventions: None. Measurements and Main Results: We reviewed the imaging reports to determine injury progression. Potential predictors of worsening computed tomography findings and neurosurgical intervention were recorded by chart review. Logistic regression and recursive partitioning were used to identify predictors. Twenty percent (50 of 257) of patients with mild head injury had worsening computed tomography findings, and three patients (1%) had subsequent neurosurgical intervention. Patients with moderate and severe head injuries were more likely to have worsening computed tomography findings (107 of 248; 43%) and to have neurosurgical intervention (15 of 248; 6%). In most surgical patients, repeat computed tomography was preceded by rapid decline in neurologic status or elevated intracranial pressure. Stratification based on four clinical factors (initial head injury severity, any intraparenchymal finding on initial computed tomography, normal findings on initial computed tomography, coagulopathy) identified 100% of the surgical patients and 89% of patients with worsening brain injuries on the repeat computed tomography. Conclusions: Repeat head computed tomography imaging is frequently used. About 30% of repeated computed tomographies showed new or worsening brain injury. However, worsening brain injury on repeat computed tomography rarely resulted in neurosurgical intervention. Patients with moderate or severe head injury and intraparenchymal injuries were more likely to show worsening brain injury and undergo neurosurgical intervention.

Are we underestimating the burden of traumatic brain injury? Surveillance of severe traumatic brain injury using centers for disease control International classification of disease, ninth revision, clinical modification, traumatic brain injury codes.

BACKGROUND The epidemiology of traumatic brain injury (TBI) is often studied through the use of International classification of disease, ninth revision, clinical modification (ICD-9-CM), diagnosis codes from the Centers for Disease Control and Prevention TBI Surveillance System. Recent studies suggest that these codes may underestimate the burden of TBI because of inaccuracies and low sensitivity. OBJECTIVE To determine the sensitivity and specificity of ICD-9-CM codes in a severe TBI population. METHODS We retrospectively reviewed medical records of all hospital admissions including computed tomography of the head at a single center to identify severe blunt TBI patients, their injuries, and the neurosurgical procedures performed. We calculated sensitivity and specificity by comparing ICD-9-CM diagnosis and procedure codes assigned by hospital coders with medical records, the gold standard. RESULTS In 2008, there were 148 qualifying admissions. These codes were 89% sensitive for the presence of any severe TBI. However, one-fifth of these cases were identified only with a code defining a nonspecific head injury. Next, we studied types of TBI by categories defined by the Centers for Disease Control and Prevention (morbidity groups) and by ICD-9-CM codes for types of injury (any skull fracture, intracranial contusion, intracranial hemorrhage, concussion/loss of consciousness) and found widely varying sensitivity and specificity for both. In general, these codes had higher specificity than sensitivity. Both sensitivity and specificity were > 80% for only 2 categories: any skull fracture and intracranial hemorrhage. In contrast, we found high sensitivity and specificity for neurosurgical procedures (97% and 94%). CONCLUSION ICD-9-CM codes were sensitive for the presence of any severe TBI, but further classification of specific types of TBI was limited by variable sensitivity/specificity. Use of these codes should be supplemented by other methodology.

Posterior fossa swelling and hydrocephalus resulting from hypertensive encephalopathy: case report and review of the literature

OBJECTIVE AND IMPORTANCE: Brain stem and cerebellar edema rarely have been described as the principal manifestation of hypertensive encephalopathy. In addition, secondary hydrocephalus has been described in only a few cases in the literature. We present an unusual case of posterior fossa swelling and hydrocephalus resulting from hypertensive encephalopathy. CLINICAL PRESENTATION: A 53-year-old man presented with increased shortness of breath, headache, and visual changes, which had been worsening for several months. Blood pressure on presentation was 253/140 mm Hg. Neuroradiological studies revealed brain stem swelling predominantly affecting the pons, with compression of the adjacent cisterns and fourth ventricle and resultant hydrocephalus. The diagnosis of brain stem glioma was briefly entertained. INTERVENTION: The patients blood pressure was brought under control with medical management, and he was treated with dexamethasone for 48 hours. Subsequent neuroradiological studies revealed decreased posterior fossa edema as well as marked improvement in the hydrocephalus. CONCLUSION: Hypertensive encephalopathy can present principally in the posterior fossa and can give rise to obstructive hydrocephalus. Invasive treatment of the hydrocephalus is not necessarily required in this clinical setting because reduction of the blood pressure may result in rapid improvement of the hydrocephalus.

Diffusion tensor imaging of the spinal cord: insights from animal and human studies.

Diffusion tensor imaging (DTI) provides a measure of the directional diffusion of water molecules in tissues. The measurement of DTI indexes within the spinal cord provides a quantitative assessment of neural damage in various spinal cord pathologies. DTI studies in animal models of spinal cord injury indicate that DTI is a reliable imaging technique with important histological and functional correlates. These studies demonstrate that DTI is a noninvasive marker of microstructural change within the spinal cord. In human studies, spinal cord DTI shows definite changes in subjects with acute and chronic spinal cord injury, as well as cervical spondylotic myelopathy. Interestingly, changes in DTI indexes are visualized in regions of the cord, which appear normal on conventional magnetic resonance imaging and are remote from the site of cord compression. Spinal cord DTI provides data that can help us understand underlying microstructural changes within the cord and assist in prognostication and planning of therapies. In this article, we review the use of DTI to investigate spinal cord pathology in animals and humans and describe advances in this technique that establish DTI as a promising biomarker for spinal cord disorders.

Utility of a combined current procedural terminology and International Classification of Diseases, Ninth Revision, Clinical Modification code algorithm in classifying cervical spine surgery for degenerative changes.

Study Design. Retrospective study. Objective. To evaluate the sensitivity and specificity of a combined Current Procedural Terminology (CPT) and International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) algorithm in defining cervical spine surgery in comparison to patient operative reports in the medical record. Summary of Background Data. Epidemiological studies of spine surgery often use ICD-9-CM billing codes in administrative databases to study trends and outcome of surgery. However, ICD-9-CM codes do not clearly identify specific surgical factors that may be related to outcome, such as instrumentation or number of levels treated. Previous studies have not investigated the sensitivity and specificity of a combined CPT and ICD-9-CM code algorithm for defining cervical spine surgical procedures. Methods. We performed a retrospective study comparing the sensitivity and specificity of a combined CPT and ICD-9-CM code algorithm to the operative note, the gold standard, in a single academic center. We also compared the accuracy of our combined algorithm with our published ICD-9-CM-only algorithm. Results. The combined algorithm has high sensitivity and specificity for defining cervical spine surgery, specific surgical procedures such as discectomy and fusion, and surgical approach. Compared to the ICD-9-CM-only algorithm, the combined algorithm significantly improves identification of discectomy, laminectomy, and fusion procedures and allows identification of specific procedures such as laminaplasty and instrumentation with high sensitivity and specificity. Identification of reoperations has low sensitivity and specificity, but identification of number of levels instrumented, fused, and decompressed has high specificity. Conclusion. The use of our combined CPT and ICD-9-CM algorithm to identify cervical spine surgery was highly sensitive and specific. For categories such as surgical approach, accuracy of our combined algorithm was similar to that of our ICD-9-CM-only algorithm. However, the combined algorithm improves sensitivity, and allows identification of procedures not defined by ICD-9-CM procedure codes, and number of levels instrumented and decompressed. The combined algorithm better defines cervical spine surgery and specific factors that may impact outcome and cost.

Characterization and limitations of diffusion tensor imaging metrics in the cervical spinal cord in neurologically intact subjects.

To characterize diffusion tensor imaging (DTI) metrics across all levels of the cervical spinal cord (CSC) and to study the impact of age and signal quality on these metrics.

Strengths and limitations of International Classification of Disease Ninth Revision Clinical Modification codes in defining cervical spine surgery.

Study Design. Retrospective study. Objective. To evaluate the sensitivity and specificity of International Classification of Disease Ninth Revision Clinical Modification (ICD9-CM) hospital discharge codes to define degenerative cervical spine surgery in comparison to patient operative notes in the medical record. Summary of Background Data. Population-based studies of spine surgery have often relied on administrative databases as a primary information source, but little is known about the validity of using ICD9-CM codes to identify these operations. Methods. We performed a retrospective study comparing ICD9-CM billing codes to patient operative notes, the gold standard, for patients undergoing spine surgery in 2006 at a single academic center. Results. We identified 1090 procedures of which 265 were categorized as cervical spine surgery for degenerative indications based on the operative notes. Compared to operative notes, our ICD9-CM algorithm had high sensitivity and specificity for selecting surgery at the cervical spine level and cervical spine surgery for degenerative indications. Categorization of cases by procedure had high sensitivity and specificity for fusion and surgical approach (>95%). Categorization of cases by primary diagnosis was generally less accurate. Cervical spondylosis with myelopathy was the most sensitive primary diagnosis. Categorization of cases by procedure had high sensitivity and specificity for fusion and surgical approach (≥96%). However, diagnoses such as herniated disc and procedures such as laminectomy had low sensitivity but high specificity. Conclusion. The use of our ICD9-CM algorithm to define spine surgery at the cervical spine level, and degenerative cervical spine surgery is highly accurate. Although specific diagnoses codes are mostly insensitive, an ICD9-CM algorithm can be used to study these procedures with reasonable precision.