Sagun Tuli

Frontal and Occipital Horn Ratio: A Linear Estimate of Ventricular Size for Multiple Imaging Modalities in Pediatric Hydrocephalus

Objective: Measurement of ventricular size is important in pediatric patients with hydrocephalus, especially those who are being followed with cerebrospinal fluid (CSF) shunts. While volumetric techniques are a more accurate estimate of true ventricular volume, they are often impracticable when multiple modalities including ultrasound are used. Volumetric area and linear measurements were compared to find the most reasonable measurement method. Methods: Sixty-four computed tomography (CT), magnetic reasonance imaging (MRI), and ultrasound (US) scans from 25 children aged 0–17 years with hydrocephalus, before and after treatment, were measured. Measurements included ventricular volume, a ventricular/brain ratio, and four standard linear measures (Evans’ ratio, Huckman’s measurement, minimal lateral ventricular width, and lateral ventricular span at the body). We also included a new ratio, which accounts for often disproportionate occipital horn expansion in pediatric patients, called the frontal and occipital horn ratio. Volume and linear measurements were compared using the Spearman’s correlation coefficients and correlations were further differentiated using a Z test statistic. The frontal and occipital horn ratio was also measured on CT, MRI, and US scans from 44 normal children aged 0–17 years to identify normal values. The effect of age was determined by linear regression. Results: The best linear correlation with ventricular size was the frontal + occipital horn ratio (r = 0.852) and was equivalent to the ventricular/brain ratio (r = 0.891), previously shown to have the highest correlation with ventricular volume. Evans’ ratio correlates less well (r = 0.423). The normal frontal and occipital horn ratio is 0.37 and is independent of age. Conclusions: The frontal and occipital horn ratio is a simple method of evaluating ventricular size in pediatric hydrocephalus patients with CSF shunts.

Occipital condyle fractures.

OBJECTIVE Occipital condyle fractures (OCFs) are infrequently recognized. Three recent cases of OCF in our center prompted a review of the incidence, clinical presentation, diagnosis, and treatment of this entity. METHODS A retrospective review of medical records and radiographic results was performed for 93 of 316 consecutive patients who were victims of trauma, who presented at the Toronto Hospital during a 13-month period, and who had undergone computed tomography of the occiput. RESULTS A review of the literature regarding OCF revealed that cranial nerve deficits occurred in 31% of the patients with OCFs; of those, the deficits were delayed in 38%. Three new cases of OCF, with neck pain but without cranial nerve deficits, have been reported. The cervical spine x-rays revealed nothing abnormal in 96% of the reported cases. In our retrospective review, asymptomatic OCF was revealed by computed tomography for 1 of the 93 patients. CONCLUSION OCF is a diagnostic challenge. We suggest that computed tomographic scans of O-C2 be obtained in the following circumstances: presence of lower cranial nerve deficits, associated head injury or basal cranial fracture, or persistent severe neck pain despite normal radiographic results. We propose a new classification system for the management and treatment of OCF based on the stability of the O-C1-C2 joint complex reflected by the presence of displacement of the condyle, computed tomographic or radiographic evidence of O-C1-C2 instability, and magnetic resonance evidence of ligamentous injury. OCFs are divided into the following types: Type 1 (stable), undisplaced fracture; Type 2A (stable), displaced fracture with no ligamentous instability; and Type 2B (unstable), displaced fracture with ligamentous instability.

CSF shunts 50 years on--past, present and future.

Abstract Cerebrospinal fluid (CSF) shunts were invented almost 50 years ago. While their introduction revolutionized the treatment of hydrocephalus, their complications have become legendary, and the focus of much investigation and development of new devices. New devices have been based upon improved understanding of the pathophysiology of hydrocephalus or shunt complications. Despite the rational, or frequently ”more physiological,” functioning of these devices, all too often unexpected complications have ensued, and the initial enthusiasm for the devices has waned. Assessing the efficacy of the devices has been difficult, owing to the lack of properly conducted studies. Nevertheless, the overall impact of shunt design improvements has seemed very limited. A recent randomized trial of CSF shunt design, examining the failure rates of two new and widely used valves (the Cordis Orbis Sigma and the Medtronic PS Medical Delta valves) failed to find any advantage of these over standard valve designs, many of which have been used almost since the inception of CSF shunts. A search for risk factors for failure, in a post hoc analysis of the data, indicated only that the etiology of the hydrocephalus and the position and local environment of the ventricular catheter tip were probably important. Remarkably, the rate of change in the size of the ventricles and the final ventricular size were not different despite the substantial differences in flow characteristics of the two new valves. Shunt failure rates of less than 5% at 1 year, with infection rates of less than 1%, seem like reasonable goals for the next decade in the new millenium. This can be achieved through basic research into the pathophysiology of shunt failure with improved mathematical models, and perhaps animal models of shunt failure. Efficacy of new devices or treatments must be scrutinized scientifically so as not to waste valuable resources and time on unproven treatments. Uncontrolled series and testimonial assertions about new treatments or devices, especially from proponents with a vested interest, should be regarded with great skepticism. Nevertheless, our best efforts are likely to result in a major advance in the management of pediatric hydrocephalus, which now seems tantalizingly close.

Third Ventriculostomy versus Cerebrospinal Fluid Shunt as a First Procedure in Pediatric Hydrocephalus

Background: Third ventriculostomy (TV) has been reported to be efficacious for diverse causes of obstructive hydrocephalus in pediatric patients, and preferable to a first CSF shunt (CS) in those eligible. We reviewed the respective failure rates in a prospective cohort of patients at our institution. Method: All patients having either TV or CS (i.e ventriculoperitoneal shunt) over the period 1987 to 1997 were prospectively entered into a database. To compare homogeneous patients, only diagnoses of either aqueductal stenosis or tumor were considered. Failure was defined as any subsequent surgical procedure for CSF diversion. Kaplan-Meier curves were constructed to determine survivorship. A multivariable Cox model using time-dependent covariates was constructed. Results: There were 32 TV and 210 CS patients: 14 (44%) and 95 (45%) failed, respectively. TV patients were older (median age = 8.1 vs. 3.6 years) and had a higher incidence of aqueductal stenosis (53 vs. 25%). There was no statistically significant difference between the two procedures based on bivariate analysis (p = 0.87) and on multivariable analysis using the Cox model after adjusting for the potential confounders (p = 0.66, hazard ratio = 1.19, 95% confidence interval = 0.55-2.56). Conclusion: Failure from TV is not unlike that of CS when analyzed by survival methods. Larger prospective series are needed to look at specific subgroups who may benefit from TV. Quality of life and clinical outcome measures are also required to analyze the difference between these two procedures.

Multiple shunt failures: an analysis of relevant factors.

Ventricular shunts that require multiple revisions are familiar to pediatric neurosurgeons. We conducted a retrospective study to determine whether patients who require repeated shunt revisions represent a particular cohort within shunted hydrocephalic children. The clinical records of 244 children who had undergone shunt procedures between January 1990 and January 1996 were examined. They were divided into group 1: children with no shunt failure (n=136), group 2: children with one shunt revision (n=52), group 3: children with 2 or 3 shunt revisions (n=34), and group 4: patients who had 4 or more shunt revisions (n=22). Patients in groups 3 and 4 accounted for 54.8% of the total of 531 shunt procedures. Etiology of hydrocephalus, nature of the dysfunction, CSF characteristics, and variables related to the surgical procedure were analyzed for each group. We observed a progressive shortening of the intervals between revisions as the numbers of surgeries increased, indicating that shunts that tended to fail repeatedly did so sooner than those that did not. A Kaplan-Meier shunt survival curve showed that group 2 had a slower rate of failure than either group 3 (χ2=7.13, P<0.01) or group 4 (χ2=4.76, P<0.05). The etiologies of the hydrocephalus were not randomly distributed among the four groups (χ2=81.4, P<0.001); there was a predominance of congenital conditions in group 1. Repeated shunt revisions were associated with a progressive increase in the concentration of monocytes in the CSF (Kruskal-Wallis, P<0.05). Our data suggest that multiple shunt revisions constitute a phenomenon that may be caused by specific, still unidentified, biological factors.

Reliability of radiologic assessment of fusion: cervical fibular allograft model.

Study Design. Prospective assessment of the reliability of determining cervical fusion success based on plain radiographs. Objectives. Determination of the reliability of plain static radiographs in predicting the presence or absence of fusion. Summary of Background Data. The ability of plain radiographs to assess the presence of fusion is limited. In addition, variations in the definition of “fusion” make this entity an important aspect for study. Methods. A study was carried out to determine the reliability of plain radiographs in predicting bony fusion. Cases of cervical spondylosis undergoing a single or multilevel corpectomy with an allograft fusion and anterior instrumentation were chosen for the model. The definition of “bony fusion” was obtained from the literature. Bony fusion was defined by the presence of bony trabeculation across the graft–host interfaces, the assessment of the change in strut height over time, and the development of a kyphotic angulation over time. Data were collected at a tertiary care institution over a 5-year period. Descriptive statistics regarding baseline patient characteristics, the underlying disease process, and the surgical intervention, were obtained. Reliability of plain static radiographs in assessing fusion was evaluated by two independent neuroradiologists blinded to any subsequent clinical outcome. The Cohen Kappa statistic was used to determine the degree of agreement regarding the presence or absence of fusion at the superior and inferior aspect of the graft at the 6-week and the 12-week follow-up. Results. The study involved 57 patients (30 males and 27 females), with a median age of 49 years. The number of levels decompressed was 1, 2, and 3 in 36, 20, and 1 patients, respectively. Fourteen patients had a history of smoking. The Cohen Kappa statistic revealed variable results depending on the time period and aspect evaluated. The degree of agreement at 6 weeks was 0.61 (95% confidence interval = 0.32–0.89) and 0.44 (95% confidence interval = 0.017–0.86) and at 12 weeks was 0.18 (95% confidence interval = –0.21–0.58) and 1.00 for the superior and inferior aspect of the graft, respectively. Conclusions. Plain radiographs are generally quite unreliable in predicting fusion based on presence or absence of trabeculation.

Lhermitte-Duclos disease: literature review and novel treatment strategy.

BACKGROUND Lhermitte-Duclos disease (LDD) is a rare pathologic entity involving the cerebellum. The fundamental nature of the entity and its pathogenesis remain unknown, and considerable debate has centered on whether it represents a neoplastic, malformative or hamartomatous lesion. The cell or cells of origin remain incompletely defined. Previous reports of cases in the English literature have dealt predominantly with the clinical and pathological aspects yet few address issues of treatment. METHODS A case of Lhermitte-Duclos disease (LDD) in a 54-year-old female leading to local compressive symptoms and obstructive hydrocephalus is presented. A craniectomy, in addition to a C1 laminectomy followed by a decompressive duroplasty (using autologous fascia lata graft) was performed. RESULTS The patient clinically improved and follow-up MRI 11 months post-operatively revealed improvement in hydrocephalus. CONCLUSION The histological and immunohistochemical features of the lesion are described, emphasizing the role of an abnormal dysplastic granule cell layer. The evidence in favor of each of the major theories of pathogenesis, malformative and neoplastic is discussed. Based on these facts a form of surgical intervention involving decompressive duroplasty is proposed.

Predictors of survival in patients with prostate cancer and spinal metastasis. Presented at the 2009 Joint Spine Section Meeting. Clinical article.

OBJECT Prostate cancer is the second most common malignancy to cause death in men, with metastases to the spine being the most common site of metastatic burden. A retrospective observational study was performed to determine survival of patients in whom spinal metastasis from prostate cancer had been diagnosed. METHODS The patient population was obtained from the Prostate Clinical Research Information System (CRIS) at the Dana-Farber Cancer Institute. Patients were observed over a period of 19 years, between June 1990 and April 2009. Clinical covariates were studied in their relationship to overall survival, the primary outcome, by using the Kaplan-Meier method and Cox regression. RESULTS Of a total of 9010 patients in the Prostate CRIS database, 333 were identified as having developed spinal metastases. The median overall survival after diagnosis of spinal metastasis was 24 months (95% CI 21-28 months). The estimated 1-year overall survival was 73% (95% CI 67%-77%). In 85% of patients, at least 1 additional site of metastasis was documented. Among 28 patients who had no additional sites of metastases, the median survival was 55.9 months, whereas an increasing burden of disease was associated with shorter survival (p = 0.0001). The association was observed regardless of whether the metastatic burden was characterized as the presence of additional (nonspinal) bone metastasis, the presence of additional nonbone metastasis, or as the number of concomitant metastatic sites (all p = 0.0001). In multivariate analysis, a higher prostate-specific antigen level at the diagnosis of spinal metastasis, a longer duration between the diagnosis of prostate cancer and spinal metastasis, and the presence of additional metastasis at the time of diagnosis of spinal metastasis (all p = 0.0001) were independently associated with a shorter overall survival. CONCLUSIONS The results of this study are important for oncologists, neurosurgeons, and primary care physicians who have patients with prostate cancer that metastasizes to the spine, because these results can be used to form a prognosis and guide the physician in making appropriate decisions regarding the patients treatment. Future work should include building a predictive model that accurately determines survival in patients with metastatic disease, because this would guide the physician in devising the most appropriate treatment plan for each patient.

A comparison of long-term outcomes of translaminar facet screw fixation and pedicle screw fixation: a prospective study

OBJECT In this paper, the authors compare the long-term outcomes of translaminar facet screw fixation (TFSF) and pedicle screw fixation (PSF) in the treatment of degenerative lumbosacral disease. METHODS This prospective analytical study was performed to compare the long-term outcomes of TFSF and PSF for degenerative lumbosacral disease. Outcomes were defined as the need for reoperation for the development of a nonunion, end-fusion degeneration, or for explantation of hardware. RESULTS A total of 77 patients were analyzed. Thirty-seven patients underwent PSF and 40 received TFSF. Twenty-three of the 77 patients required a reoperation: 13 (32.5%) of the 40 patients in the TFSF group and 10 (27%) of the 37 the patients in the PSF group. The overall mean time to reoperation (regardless of outcome) was 4.05 years. For patients in the TFSF group the mean time to reoperation was 2.94 years, whereas it was 4.35 years in the PSF group (p = 0.34). Nonunion was noted in seven of the 40 patients in the TFSF group and one of 37 in the PSF group. The mean time to surgery for nonunion for patients in the TFSF group was 3.46 years and for those in the PSF group it was 6.27 years (p = 0.04). Surgery for end-fusion degeneration was performed in two patients in the TFSF group and five in the PSF group (p = 0.43). Explantation of hardware was performed in two patients with TFSF and four patients with PSF. Multivariable analysis revealed a statistically significant difference in the time to surgery for nonunion between PSF and TFSF (p = 0.048), with a hazard ratio of 0.097 (95% confidence interval 0.01-0.98). CONCLUSIONS Findings from the current prospective study suggest that there is an increased risk of requirement for a reoperation for nonunion among TFSF cases compared with PSF cases.

Comparison of perioperative morbidity in translaminar facet versus pedicle screw fixation.

This retrospective study evaluated the perioperative morbidity of patients undergoing lumbar, sacral, or lumbosacral fusion using either pedicle or translaminar facet screw fixation following interbody fusion. Hospital charts of all patients who presented to a single tertiary care institution during a 4-year period were reviewed. Findings indicated translaminar facet screw fixation was a less invasive spinal fixation method with decreased perioperative morbidity compared to pedicle screw fixation.