Development of a mapping function ("crosswalk") for the conversion of scores between the Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI)

INTRODUCTION

The Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) are two commonly used self-rating outcome instruments in patients with lumbar spinal disorders. No formal crosswalk between them exists that would otherwise allow the scores of one to be interpreted in terms of the other. We aimed to create such a mapping function.

METHODS

We performed a secondary analysis of ODI and COMI data previously collected from 3324 patients (57 ± 17y; 60.3% female) at baseline and 1y after surgical or conservative treatment. Correlations between scores and Cohen's kappa for agreement (κ) regarding achievement of the minimal clinically important change (MCIC) score on each instrument (ODI, 12.8 points; COMI, 2.2 points) were calculated, and regression models were built. The latter were tested for accuracy in an independent set of registry data from 634 patients (60 ± 15y; 56.8% female).

RESULTS

All pairs of measures were significantly positively correlated (baseline, 0.73; 1y follow-up (FU), 0.84; change-scores, 0.73). MCIC for COMI was achieved in 53.9% patients and for ODI, in 52.4%, with 78% agreement on an individual basis (κ = 0.56). Standard errors for the regression slopes and intercepts were low, indicating excellent prediction at the group level, but root mean square residuals (reflecting individual error) were relatively high. ODI was predicted as COMI × 7.13-4.20 (at baseline), COMI × 6.34 + 2.67 (at FU) and COMI × 5.18 + 1.92 (for change-score); COMI was predicted as ODI × 0.075 + 3.64 (baseline), ODI × 0.113 + 0.96 (FU), and ODI × 0.102 + 1.10 (change-score). ICCs were 0.63-0.87 for derived versus actual scores.

CONCLUSION

Predictions at the group level were very good and met standards justifying the pooling of data. However, we caution against using individual values for treatment decisions, e.g. attempting to monitor patients over time, first with one instrument and then with the other, due to the lower statistical precision at the individual level. The ability to convert scores via the developed mapping function should open up more centres/registries for collaboration and facilitate the combining of data in meta-analyses.

Development of a machine-learning based model for predicting multidimensional outcome after surgery for degenerative disorders of the spine

BACKGROUND

It is clear that individual outcomes of spine surgery can be quite heterogeneous. When consenting a patient for surgery, it is important to be able to offer an individualized prediction regarding the likely outcome. This study used a comprehensive set of data collected over 12 years in an in-house registry to develop a parsimonious model to predict the multidimensional outcome of patients undergoing surgery for degenerative pathologies of the thoracic, lumbar or cervical spine.

METHODS

Data from 8374 patients (mean age 63.9 (14.9-96.3) y, 53.4% female) were used to develop a model to predict the 12-month scores for the Core Outcome Measures Index (COMI) and its subdomain scores. The data were split 80:20 into a training and test set. The top predictors were selected by applying recursive feature elimination based on LASSO cross validation models. Based on the 111 top predictors (contained within 20 variables), Ridge cross validation models were trained, validated, and tested for each of 9 outcome domains, for patients with either "Back" (thoracic/lumbar spine) or "Neck" (cervical spine) problems (total 18 models).

RESULTS

Among the strongest outcome predictors in most models were: preoperative scores for almost all COMI items (especially axial pain (back or neck) and peripheral pain (leg/buttock or arm/shoulder)), catastrophizing, fear avoidance beliefs, comorbidity, age, BMI, nationality, previous spine surgery, type and spinal level of intervention, number of affected levels, and surgeon seniority. The R² of the models on the validation/test sets averaged 0.16/0.13. A preliminary online tool was programmed to present the predicted outcomes for individual patients, based on their presenting characteristics. https://linkup.kws.ch/prognostictool .

CONCLUSION

The models provided estimates to enable a bespoke prediction of the outcome of surgery for individual patients with varying degenerative pathologies and baseline characteristics. The models form the basis of a simple, freely-available online prognostic tool developed to improve access to and usability of prognostic information in clinical practice. It is hoped that, following confirmation of its validity and practical utility, the tool will ultimately serve to facilitate decision-making and the management of patients' expectations.

Patient-rated outcome after atlantoaxial (C1-C2) fusion: more than a decade of evaluation of 2-year outcomes in 126 patients

INTRODUCTION

Various surgical techniques have been introduced for atlantoaxial (C1-C2) fusion, the most common being Magerl's (transarticular) or the Harms/Goel screw fixation. Common indications include degenerative osteoarthritis (OA), trauma or rheumatoid arthritis (RA). Only few, small studies have evaluated patient-reported outcomes after C1-C2 fusion. We investigated 2-year outcomes in a large series of consecutive patients undergoing isolated C1-C2 fusion.

METHODS

We analysed prospectively collected data (2005-2016) from our Spine outcomes database, collected within the framework of EUROSPINE's Spine Tango Registry. It included 126 patients (34 (27%) men, 92 (73%) women; mean (SD) age 67 ± 19 y) who had undergone first-time isolated C1-C2 fusion (61% Magerl, 39% Harms(-Goel)) at least 2 years ago for OA (83 (66%)), RA (20 (16%)), fracture (15 (12%)) or other (8 (6%)). Patients completed the multidimensional Core Outcome Measures Index (COMI; 0-10) and various single item outcomes.

RESULTS

Questionnaires were returned by 118/126 (94%) patients, 2 years post-operative. Mean COMI scores showed a significant reduction from baseline: 6.9 ± 2.4 to 2.7 ± 2.5 (p < 0.0001). Overall, 75% patients achieved the MCIC of ≥ 2.2 points reduction in COMI and 88% reported a good global outcome. 91% patients were satisfied/very satisfied with their care. Self-reported complications were declared by 16% patients and further surgery at the same segment, by 2.5%.

CONCLUSION

In this large series with almost complete follow-up, C1-C2 fusion showed extremely good results. Despite the complexity of the intervention, outcomes surpassed those typically reported for simple procedures such as ACDF and lumbar discectomy, suggesting reservations about the procedure should perhaps be reviewed.

How does patient-rated outcome change over time following the surgical treatment of degenerative disorders of the thoracolumbar spine?

PURPOSE

Patient-rated measures are considered the gold standard for assessing the outcome of spine surgery, but there is no consensus on the appropriate timing of follow-up. Journals often demand a minimum 2-year follow-up, but the indiscriminate application of this principle may not be warranted. We examined the course of change in patient outcomes up to 5 years after surgery for degenerative spinal disorders.

METHODS

The data were evaluated from 4287 consecutive patients (2287 women, 2000 men; aged 62 ± 15 years) with degenerative disorders of the thoracolumbar spine, undergoing first-time surgery at the given level between 01/01/2005 and 31/12/2011. The Core Outcome Measures Index (COMI; scored 0-10) was completed by 4012 (94%) patients preoperatively, 4008 (93%) at 3-month follow-up, 3897 (91%) at 1-year follow-up, 3736 (87%) at 2-year follow-up, and 3387 (79%) at 5-year follow-up. 2959 (69%) completed the COMI at all five time-points.

RESULTS

The individual COMI change scores from preoperatively to the various follow-up time-points showed significant correlations ranging from r = 0.50 (for change scores at the earliest vs the latest follow-up) to r = 0.75 (for change scores after 12- vs 24-month follow-up). Concordance with respect to whether the minimum clinically important change score was achieved at consecutive time-points was also good (70-82%). COMI decreased significantly (p < 0.05) from preop to 3 months (by 3.6 ± 2.8 points) and from 3 to 12 months (by 0.3 ± 2.4 points), then levelled off up to 5 years (0.04-0.05 point change; p > 0.05). The course of change up to 12 months differed slightly (p < 0.05) depending on pathology/whether fusion was carried out. For patients undergoing simple decompression, 3-month follow-up was sufficient; those undergoing fusion continued to show further slight but significant change up to 12 months.

CONCLUSIONS

Stable group mean COMI scores were observed for all patients from 12 months postoperatively onwards. The early postoperative results appeared to herald the longer term outcome. As such, a 'wait and see policy' in patients with a poor initial outcome at 3 months is not advocated. The insistence on a 2-year follow-up could result in a failure to intervene early to achieve better long-term outcomes.

A novel use of the Spine Tango registry to evaluate selection bias in patient recruitment into clinical studies: an analysis of patients participating in the Lumbar Spinal Stenosis Outcome Study (LSOS)

PURPOSE

Patients enrolled in clinical studies typically represent a sub-set of all who are eligible, and selection bias may compromise the generalizability of the findings. Using Registry data, we evaluated whether surgical patients recruited by one of the referring centres into the Lumbar Spinal Stenosis Outcome Study (LSOS; a large-scale, multicentre prospective observational study to determine the probability of clinical benefit after surgery) differed in any significant way from those who were eligible but not enrolled.

METHODS

Data were extracted for all patients with lumbar spinal stenosis registered in our in-house database (interfaced to Eurospine's Spine Tango Registry) from 2011 to 2013. Patient records and imaging were evaluated in relation to the admission criteria for LSOS to identify those who would have been eligible for participation but were not enrolled (non-LSOS). The Tango surgery data and Core Outcome Measures Index (COMI) data at baseline and 3 and 12 months after surgery were analysed to evaluate the factors associated with LSOS enrolment or not.

RESULTS

514 potentially eligible patients were identified, of which 94 (18%) were enrolled into LSOS (range 2-48% for the 6 spine surgeons involved in recruiting patients) and 420 (82%) were not; the vast majority of the latter were due to non-referral to the study by the surgeon, with only 5% actually refusing participation. There was no significant difference in gender, age, BMI, smoking status, or ASA score between the two groups (p ≥ 0.18). Baseline COMI was significantly (p = 0.002) worse in the non-LSOS group (7.4 ± 1.9) than the LSOS group (6.7 ± 1.9). There were no significant group differences in any Tango surgery parameters (additional spine patholothegies, operation time, blood loss, complications, etc.) although significantly more patients in the non-LSOS group had a fusion procedure (38 vs 18% in LSOS; p = 0.0004). Postoperatively, neither the COMI nor its subdomain scores differed significantly between the groups (p > 0.05). Multiple logistic regression revealed that worse baseline COMI (p = 0.021), surgeon (p = 0.003), and having fusion (p = 0.014) predicted non-enrolment in LSOS.

CONCLUSION

A high proportion of eligible patients were not enrolled in the study. Non-enrolment was explained in part by the specific surgeon, worse baseline COMI status, and having a fusion. The findings may reflect a tendency of the referring surgeon not to overburden more disabled patients and those undergoing more extensive surgery with the commitments of a study. Beyond these factors, non-enrolment appeared to be somewhat arbitrary, and was likely related to surgeon forgetfulness, time constraints, and administrative errors. Researchers should be aware of potential selection bias in their clinical studies, measure it (where possible) and discuss its implications for the interpretation of the study's findings.

Validity of a single-item measure to assess leg or back pain as the predominant symptom in patients with degenerative disorders of the lumbar spine

PURPOSE

Recent studies suggest that the location of predominant pain (back or leg) can be a significant predictor of the outcome of surgery for degenerative spinal disorders. However, others challenge the notion that the predominant symptom can be reliably identified. This study examined the validity of a single item used to determine the most troublesome symptom.

METHODS

A total of 2,778 patients with degenerative disorders of the lumbar spine scheduled for surgery with the goal of pain relief completed a questionnaire enquiring as to their most troublesome symptom ["main symptom"; back pain (BACK) or leg/buttock pain (LEG)]. They also completed separate 0-10 graphic rating scales for back pain (LBP) and leg/buttock pain (LP) intensity. Receiver operating characteristics (ROC) analysis was used to determine the accuracy with which the "LP minus LBP" score was able to classify patients into their declared "main symptom" group. Sub-studies evaluated the test-retest reliability of the patients' self-rated pain scores (N = 45) and the agreement between the main symptom declared by the patient in the questionnaire and that documented by the surgeon after the clinical consultation (N = 118).

RESULTS

Test-retest reliability of the back and leg pain scores was good (ICC₂,₁ of 0.8 for each), as was patient-surgeon agreement regarding the main symptom (BACK or LEG) (κ value 0.79). In the BACK group, the mean values for pain intensity were 7.3 ± 2.0 (LBP) and 5.2 ± 2.9 (LP); in the LEG group, they were 4.3 ± 2.9 (LBP) and 7.5 ± 1.9 (LP). The area under the curve for the ROC was 0.95 (95 % CI 0.94-0.95), indicating excellent discrimination between the BACK and LEG groups based on the "LP minus LBP" scores. A cutoff score >0.0 for "LP minus LBP" score gave optimal sensitivity and specificity for indicating membership of the LEG group (sensitivity 79.1%, specificity 95.7%).

CONCLUSIONS

The responses on the single item for the "main symptom" were in good agreement with the differential ratings on the 0-10 pain scales for LBP and LP intensity. The cutoff >0 for "LP minus LBP" for classifying patients as LEG pain predominant seemed appropriate and suggests good concurrent validity for the single-item measure. The single item may be of use in sub-grouping patients with the same disorder (e.g. spondylolisthesis) or as an indication in surgical decision-making.

Surgery in lumbar degenerative spondylolisthesis: indications, outcomes and complications. A systematic review

PURPOSE

This systematic review summarises the literature on patient selection, decision-making, effectiveness and outcomes in the surgical treatment of lumbar degenerative spondylolisthesis (LDS).

INTRODUCTION

In daily practice, decision-making in the treatment of LDS is challenging. There is little consensus on either the precise indications or prognostic factors for any specific therapy (operative or non-operative).

METHODS

We searched for LDS trials published between 01.01.1990 and 16.11.2011 in Medline, Embase, Cochrane Library and Cinahl. Two independent reviewers selected studies according to the inclusion criteria. Data were then extracted by two of the authors. Quality assessment was performed using the Downs and Black list for the clinical trials/studies and AMSTAR for the reviews.

RESULTS

DATA SYNTHESIS

21 papers met the inclusion criteria (2 studies comprising both a RCT and a concurrent observational analysis, 1 RCT, 6 prospective studies, 8 retrospective studies, 3 reviews, 1 review guideline). The quality of the clinical studies was on average "fair" [mean score 15.6 points (range 10-19) out of 24 points (Downs and Black)]. The quality of the reviews ranged from 1 to 7 out of 11 points with an average of 5 points (AMSTAR). The study outcomes could not be subject to meta-analysis due to heterogeneity of study design and variable measure used.

CONCLUSIONS

Despite there being many articles describing and/or comparing different surgical options for LDS, there was insufficient evidence to draw conclusions concerning clear indications for specific types of surgical treatment, predictors of outcome or complication rates. There remains a need to establish a decision-making tool to facilitate daily clinical practice and to assure appropriate treatment for patients with LDS.

The bothersomeness of patient self-rated "complications" reported 1 year after spine surgery

PURPOSE

The last few decades have witnessed a paradigm shift in the assessment of outcome in spine surgery, with patient-centred questionnaires superseding traditional surgeon-based assessments. The assessment of complications after surgery and their impact on the patient has not enjoyed this same enlightened approach. This study sought to quantify the incidence and bothersomeness of patient-rated complications 1 year after surgery.

METHODS

Patients with lumbar degenerative disorders, operated with the goal of pain relief between October 2006 and September 2010, completed a questionnaire 1 year postoperatively enquiring about complications arising as a consequence of their operation. They rated the bothersomeness of any such complications on a 5-point scale. Global outcome of surgery and satisfaction at the 12-month follow-up were also rated on 5-point Likert scales. The multidimensional Core Outcome Measures Index (COMI) was completed preoperatively and at the 12-month follow-up.

RESULTS

Of 2,282 patients completing the questionnaire (92% completion rate), 687 (30.1%) reported complications, most commonly sensory disturbances (36% of those with complications) or ongoing/new pain (26%), followed by motor problems (8%), pain plus neurological disturbances (11%), and problems with wound healing (6%). The corresponding "bothersomeness" ratings for these were: 1% not at all, 23% slightly, 27% moderately, 31% very, and 18% extremely bothersome. The greater the bothersomeness, the worse the global outcome (Rho = 0.51, p < 0.0001), patient satisfaction (Rho = 0.44, p < 0.0001) and change in COMI score (Rho = 0.52, p < 0.0001).

CONCLUSION

Most complications reported by the patient are perceived to be at least moderately bothersome and hence are not inconsequential. Complications and their severity should be assessed from both the patient's and the surgeon's perspectives--not least to better understand the reasons for poor outcome and dissatisfaction with treatment.

To fuse or not to fuse in lumbar degenerative spondylolisthesis: do baseline symptoms help provide the answer?

INTRODUCTION

Clinical symptoms in lumbar degenerative spondylolisthesis (LDS) vary from predominantly radiating pain to severe mechanical low back pain. We examined whether the outcome of surgery for LDS varied depending on the predominant baseline symptom and the treatment administered [decompression with fusion (D&F) or decompression alone (D)].

METHODS

213 consecutive patients (69 ± 9 years; 155f, 58 m) participated. Inclusion criteria were LDS, maximum three affected levels, no previous surgery at the affected level, and D (N = 56) or D&F (N = 157) as the operative procedure. Pre-op and at 12 months' follow-up (FU), patients completed the multidimensional Core Outcome Measures Index (COMI) including 0-10 leg-pain (LP) and LBP scales. At 12 months' FU, patients rated global outcome which was then dichotomised into "good" and "poor".

RESULTS

Pre-operatively, LBP and COMI scores were significantly worse (p < 0.05) in the D&F group than in the D group. The improvement in COMI at 12 months' FU was significantly greater for D&F than for D (p < 0.001) and was not influenced by the patient's declared "main problem" at baseline (back pain, leg pain, or neurological disturbances) (p > 0.05). There was a higher proportion (p = 0.01) of "good" outcomes at 12 months' FU in D&F (86%) than in D (70%). Multiple regression analysis, controlling for possible confounders, revealed treatment group to be the only significant predictor of outcome (adding fusion = better outcome).

DISCUSSION

Our study indicated that LDS patients showed better patient-based outcome with instrumented fusion and decompression than with decompression alone, regardless of baseline symptoms. This may be due to the fact that the underlying slippage as the cause of the stenosis is better addressed with fusion.

Microdiscectomy compared with standard discectomy: an old problem revisited with new outcome measures within the framework of a spine surgical registry

Studies comparing the relative merits of microdiscectomy and standard discectomy report conflicting results, depending on the outcome measure of interest. Most trials are small, and few have employed validated, multidimensional patient-orientated outcome measures, considered essential in outcomes research. In the present study, data were collected prospectively from six surgeons participating in a surgical registry. Inclusion criteria were: lumbar/lumbosacral degenerative disease; discectomy/sequestrectomy without additional fusion/stabilisation; German or English-speaking. Before and 3 and 12 months after surgery, patients completed the Core Outcome Measures Index comprising questions on leg/buttock pain, back pain, back-related function, symptom-specific well-being, general quality-of-life, and social and work disability. At follow-up, they rated overall satisfaction, global outcome, and perceived complications. Compliance with the registry documentation was excellent: 87% for surgeons (surgery forms), 91% for patients (for 12 months follow-up). 261 patients satisfied the inclusion criteria (225 microdiscectomy, 36 standard discectomy). The standard discectomy group had significantly greater blood-loss than the microdiscectomy (P < 0.05). There were no group differences in the proportion of surgical complications or duration of hospital stay (P > 0.05). The groups did not differ in relation to any of the patient-orientated outcomes or individual outcome domains (P > 0.05). Though not equivalent to an RCT, the study included every single eligible patient in our Spine Center and allowed surgeons to use their regular procedure; it hence had extremely high external validity (relevance/generalisability). There was no clinically relevant difference in outcome after lumbar disc excision dependent on the use of the microscope. The decision to use the microscope should rest with the surgeon.

The quality of spine surgery from the patient's perspective. Part 1: the Core Outcome Measures Index in clinical practice

The Core Outcome Measures Index (COMI) is a short, multidimensional outcome instrument, with excellent psychometric properties, that has been recommended for use in monitoring the outcome of spinal surgery from the patient's perspective. This study examined the feasibility of implementation of COMI and its performance in clinical practice within a large Spine Centre. Beginning in March 2004, all patients undergoing spine surgery in our Spine Centre (1,000-1,200 patients/year) were asked to complete the COMI before and 3, 12 and 24 months after surgery. The COMI has one question each on back (neck) pain intensity, leg/buttock (arm/shoulder) pain intensity, function, symptom-specific well being, general quality of life, work disability and social disability, scored as a 0-10 index. At follow-up, patients also rated the global effectiveness of surgery, and their satisfaction with their treatment in the hospital, on a five-point Likert scale. After some fine-tuning of the method of administration, completion rates for the pre-op COMI improved from 78% in the first year of operation to 92% in subsequent years (non-response was mainly due to emergencies or language or age issues). Effective completion rates at 3, 12 and 24-month follow-up were 94, 92 and 88%, respectively. The 12-month global outcomes (from N = 3,056 patients) were operation helped a lot, 1,417 (46.4%); helped, 860 (28.1%); helped only little, 454 (14.9%); did not help, 272 (8.9%); made things worse, 53 (1.7%). The mean reductions in COMI score for each of these categories were 5.4 (SD2.5); 3.1 (SD2.2); 1.3 (SD1.7); 0.5 (SD2.2) and -0.7 (SD2.2), respectively, yielding respective standardised response mean values ("effect sizes") for each outcome category of 2.2, 1.4, 0.8, 0.2 and 0.3, respectively. The questionnaire was feasible to implement on a prospective basis in routine practice, and was as responsive as many longer spine outcome questionnaires. The shortness of the COMI and its multidimensional nature make it an attractive option to comprehensively assess all patients within a given Spine Centre and hence avoid selection bias in reporting outcomes.

Multimodal intraoperative monitoring (MIOM) during surgical decompression of thoracic spinal stenosis in 36 patients

A prospective study of 36 patients who received multimodal intraoperative monitoring (MIOM) during decompression of thoracic spinal stenosis between March 2000 and December 2005 was chosen as the study design. The objective was to determine the sensitivity and specificity of MIOM techniques used for monitoring spinal cord during surgical thoracic decompression. The background data revealed that the surgical decompression for thoracic spinal stenosis is less frequent than in other regions of the spine. However, due to the relative narrow spinal canal, neurological complications could be severe. The combination of monitoring ascending and descending pathways may provide an early alert to the surgeon in order to alter the surgical procedure, and avoid neurological complications. The methods involved evaluation of intraoperative somatosensory spinal and cerebral evoked potentials and motor evoked potentials of the spinal cord and muscles that were compared with post operative clinical neurological changes. 36 consecutive patients with thoracic spinal stenosis of different aetiologies were monitored by the means of MIOM during the surgical procedure. 31 patients had true negative while one patient had false positive findings. Three patients had true positive and one patient had false negative findings. This indicates a sensitivity of 75% and a specificity of 97%. The one case of false negative findings recovered completely within 3 months. In conclusion, the MIOM is an effective method of monitoring the spinal cord during surgical decompression of the thoracic spine.

Cerebral vascular autoregulation assessed by perfusion-CT in severe head trauma patients

PURPOSE

To use perfusion-CT technique in order to characterize cerebral vascular autoregulation in a population of severe head trauma patients with features of cerebral edema either on the admission or on the follow-up conventional noncontrast cerebral CT.

MATERIAL AND METHODS

A total of 80 perfusion-CT examinations were obtained in 42 severe head trauma patients with features of cerebral edema on conventional noncontrast cerebral CT, either on admission or during follow-up. Perfusion-CT results, i.e. the regional cerebral blood volume (rCBV) and flow (rCBF), were correlated with the mean arterial pressure (MAP) measured during each perfusion-CT examination. Ratios were defined to integrate the concept of cerebral vascular autoregulation, and cluster analysis performed, which allowed identification of different subgroups of patients. MAP values and perfusion-CT results in these groups were compared using Kruskal-Wallis and Wilcoxon (Mann-Whitney) tests. Moreover, the functional outcome of the 42 patients was evaluated 3 months after trauma on the basis of the Glasgow Outcome Scale (GOS) score and similarly compared between groups.

RESULTS

Three main groups of patients were identified: 1) 22 perfusion-CT examinations were collected in 13 patients, characterized by high rCBV and rCBF values and by significant dependence of perfusion-CT rCBV and rCBF results on MAP values (p<0.001), 2) 23 perfusion-CT examinations collected in 19 patients showing perfusion-CT results similar to control trauma subjects, and 3) 33 perfusion-CT collected in 16 patients, with low rCBV and rCBF values and near-independence of perfusion-CT results with respect to MAP values. The first group was interpreted as showing impaired cerebral vascular autoregulation, which was preserved in the third group. The second group was associated with the best functional outcome; it was linked to the first group, because eight patients went from one group to the other from admission to follow-up.

CONCLUSION

Perfusion-CT in severe head trauma patients was able to provide direct and quantitative assessment of cerebral vascular autoregulation with a single measurement. It could hence be used as a guide for brain edema therapy, as well as to monitor the treatment efficiency.

Early surgery for brainstem cavernomas

BACKGROUND

The purpose was to review our experience with the surgical management of brainstem cavernomas (BSCs) and especially the impact of the surgical timing on the clinical outcome.

METHOD

We retrospectively reviewed 22 patients harboring a BSC, who underwent 23 procedures.

FINDINGS

Surgery was carried out during the early stage after the last haemorrhage, with a mean delay of 21.6 days (range 4-90 days). Sixteen procedures were performed after a first bleeding event while seven after multiple bleedings. Complete resection was achieved in 19 patients (86.4%). Early after surgery, 12 patients (52.2%) improved neurologically, 5 (21.7%) were stable and 6 (26.1%) worsened. New postoperative deficits were noted after 9 procedures (39.1%). Statistically significant factors for postoperative aggravation were: late surgery (P = 0.046) and multiple bleedings (P = 0.043). No patient operated on within the first 19 days after bleeding did worsen (n = 11), as opposed to 6 out of 12 who did when operated on later. After a mean follow-up of 44.9 months, 20 patients (90.9%) were improved, 1 patient (4.6%) was worse and 1 patient was lost to follow-up (4.6%), after reoperation for rebleeding of a previously completely resected cavernoma. Late morbidity was reduced to 8.6%. The mean Glasgow Outcome Scale (GOS) at the end of the follow-up period was 4.24, compared to a mean preoperative GOS of 3.22 (P<0.001). Complete neurological recovery of motor deficits, sensory disturbances, cranial nerves (CNs), internuclear ophtalmoplegia and cerebellar dysfunction were respectively 41.7%, 38.5%, 52.6%, 60.0% and 58.3%. Among the most affected CNs: CN 3, CN 5 and CN 7 were more prone to completely recover, respectively in 60.0%, 70.0% and 69.2%.

CONCLUSIONS

Surgical removal of BSCs is feasible in experienced hands with acceptable morbidity and good outcome. Early surgery and single bleeding were associated with better surgical results.

Interdisciplinary communication

After an introduction clarifying the notion of interdisciplinarity, this chapter focuses on the importance of specific roles and mutual responsibilities within the interdisciplinary team, as well as basic rules of communication respecting the values of the concerned partners and professionals, as well as patient and family. Finally, the communication structure for efficient teamwork, and the importance of building a common vision, sharing leadership and learning to work together will be discussed.

The role of posterior fossa decompression in acute cerebellitis

BACKGROUND

We present two cases of children who were diagnosed with cerebellitis with acute cerebellar swelling. This rare pathology is potentially fatal, and no clear treatment guidelines are described in the literature.

DISCUSSION

Considering our experience, we discuss the different therapeutic strategies and propose aggressive surgical measures consisting of external ventricular drainage and posterior fossa decompression in case of failure of early response to medical treatment to limit secondary cerebellar and brainstem lesions.

The origin of brain metastases in patients with an undiagnosed primary tumour

BACKGROUND

In patients presenting brain metastases as the first manifestation of a previously undiagnosed primary tumour (UDP) histopathological confirmation of the diagnosis can be obtained by either direct surgical sampling of the brain lesion or paraclinical search for an accessible primary tumour. The sequence of the diagnostic work-up and the timing of an eventual neurosurgical intervention are a matter of debate and are mainly influenced by the distribution of primary tumours in UDP patients. The aim of this study was to verify the hypothesis that the distribution of primary tumours differs between UDP patients and the rest of the patients with brain metastases (DP), and to propose a diagnostic work-up specifically tailored to the UDP population.

METHODS

Retrospective study on 342 patients admitted to the Lausanne University hospital between 1983 and 1998 with the diagnosis of cerebral metastases.

FINDINGS

UDP patients represented 36% of the whole group. Primary tumour location was significantly different between the two groups (p=0.001). Although the lung was the most frequent primary tumour location in both groups (UDP: 60%, DP: 43%), in UDP 14% only of the primaries were found outside of the lung and as much as 26% remained unknown despite thorough investigations.

CONCLUSIONS

Our study confirmed the hypothesis that the relative frequency of primary tumours differs between DP and UDP patients. This difference therefore mandates a diagnostic strategy specifically tailored for UDP patients: if a radiological lung investigation clearly remains the best initial step in the work-up of these patients, extensive paraclinical investigations without a clear clinical suspicion should probably not be undertaken if this first survey fails to disclose the primary tumour as only 14% of the patients will actually benefit from it. In this situation, a neurosurgical procedure should probably be considered the most appropriate next step to be taken in order to provide a definitive diagnosis without unnecessary delays.

[Spinal tumors: clinical aspects, classification and surgical treatment]

Spinal tumors are classified in intradural and extradural tumors. Most extradural spinal tumors are metastasis. The other spinal tumors are rare and mostly benign. Only about 5% of tumors of the nervous system are spinal tumors. Their symptomatology is often insidious and the diagnosis can be difficult. Magnetic resonance imaging has revolutionized their diagnosis. The lesions within the spinal cord can now be directly visualized. The treatment of these tumors mostly require surgery. It has been proven that surgical results are better if these tumors are operated as soon as neurological symptoms have appeared. In our series of 39 operated intradural tumors we noted a functional improvement in 46.5% of the cases, a stabilisation in 43.5% and a deterioration in 10%.

Current strategies in the management of spinal metastatic disease

The treatment of metastatic spinal cord compression is complex. The three treatment modalities that are currently applied (in a histologically non-specific manner) are surgery, radiotherapy and the administration of steroids. The development of new spinal instrumentations and surgical approaches considerably changed the extent of therapeutic options in this field. These new surgical techniques have made it possible to resect these tumours totally, with subsequent vertebral reconstruction and spinal stabilization. In this respect, it is important to clearly identify those patients who can benefit from such an extensive surgery. We present our management algorithm to help select patients for surgery and at the same time identifying those for whom primary non-surgical therapy would be indicated. The retrospective review of surgically treated patients in our department in the last four years reveals a meagre application of conventional guidelines for the selection of the appropriate operative approach in the surgical management of these patients. The reasons for this discrepancy are discussed.

Spontaneous bilateral subdural haematomas in the posterior cranial fossa revealed by MRI

A 52-year-old woman treated for acute myeloproliferative disease developed progressive stupor. CT showed obstructive hydrocephalus resulting from unexplained mass effect on the fourth ventricle. MRI revealed bilateral extra-axial collections in the posterior cranial fossa, giving high signal on T1- and T2-weighted images, suggesting subacute subdural haematomas. Subdural haematomas can be suspected on CT when there is unexplained mass effect. MRI may be essential to confirm the diagnosis and plan appropriate treatment.

[Role of surgical treatment of low back pain and lumbo-sciatica]

Low back pain alone without any sciatica is not an appropriate indication for lumbar disc surgery. The only exception might be a clinically and radiologically proven segmental instability. However a conservative multidisciplinary treatment should precede surgery. Good and excellent results of lumbar disc surgery are achieved in 80-90% of cases. The appropriate surgical indication and the postoperative reeducation are of utmost importance for good results. The patients history, neurological examination, neuroradiological imaging and failed conservative treatment modalities are key elements to define appropriate surgical candidates. Microdisectomy remains the "gold standard" for surgical treatment of lumbar disc disease assuring a better quality of life at long term follow up.

Surgical treatment of lumbar spinal stenosis. Five-year follow-up

We carried out a retrospective review of 155 patients with lumbar spinal stenosis who had been treated surgically and followed up regularly: 77 were evaluated at a mean of 6.5 years (5 to 8) after surgery by two independent observers. The outcome was assessed using the scoring system of Roland and Morris, and the rating system of Prolo, Oklund and Butcher. Instability was determined according to the criteria described by White and Panjabi. A significant decrease in low back pain and disability was seen. An excellent or good outcome was noted in 79% of patients; 9% showed secondary radiological instability. Surgical decompression is a safe and efficient procedure. In the absence of preoperative radiological evidence of instability, fusion is not required.

Surgical treatment of lumbar spinal stenosis

We carried out a retrospective review of 155 patients with lumbar spinal stenosis who had been treated surgically and followed up regularly: 77 were evaluated at a mean of 6.5 years (5 to 8) after surgery by two independent observers. The outcome was assessed using the scoring system of Roland and Morris, and the rating system of Prolo, Oklund and Butcher. Instability was determined according to the criteria described by White and Panjabi.

A significant decrease in low back pain and disability was seen. An excellent or good outcome was noted in 79% of patients; 9% showed secondary radiological instability.

Surgical decompression is a safe and efficient procedure. In the absence of preoperative radiological evidence of instability, fusion is not required.

Appropriateness of surgery for sciatica: reliability of guidelines from expert panels

STUDY DESIGN

Reliability study of guidelines development.

OBJECTIVE

To compare criteria for low back surgery between two expert panels.

BACKGROUND

Reliability of expert panels for determining appropriateness of indications for surgical procedures has heretofore received little attention.

METHODS

Two multidisciplinary expert panels of similar composition were convened, in the United States and in Switzerland, to evaluate the appropriateness of 720 distinct clinical scenarios involving sciatica. Each indication was assigned to a category of appropriate, uncertain, and inappropriate. The appropriateness of the 720 theoretical scenarios were compared between the two panels, and both sets of criteria were applied to two series of actual cases.

RESULTS

Seventy-nine percent (n = 566) of the 720 theoretical indications were assigned to identical categories of appropriateness by both panels (kappa = 0.63; P < 0.001). Only 2 of the 720 scenarios elicited frank disagreement. The percentage of the 720 indications that were considered appropriate differed between the two panels (U.S.: 3%; Swiss: 11%, P < 0.001), as did the percentage of intrapanel agreement for indications (U.S.: 51%, Swiss: 64%, P < 0.001). When the same theoretical scenarios were matched with two series of actual cases (n = 181 and 149) agreement was moderate (kappa = 0.46) to fair (kappa = 0.30).

CONCLUSION

There was substantial agreement on the appropriateness of surgery for theoretical cases of sciatica between independent expert panels from two countries. A better understanding of discordant ratings, especially for actual cases, should precede attempts at transposing recommendations emanating from a panel in one country to another.

Cytochrome P-450 activities in human and rat brain microsomes

The role of cytochrome P450 in the metabolism of dextromethorphan, amitriptyline, midazolam, S-mephenytoin, citalopram, fluoxetine and sertraline was investigated in rat and human brain microsomes. Depending on the parameters, the limit of quantification using gas chromatography-mass spectrometry methods was between 1.6 and 20 pmol per incubation, which generally contained 1500 microg protein. Amitriptyline was shown to be demethylated to nortriptyline by both rat and human microsomes. Inhibition studies using ketoconazole, furafylline, sulfaphenazole, omeprazole and quinidine suggested that CYP3A4 is the isoform responsible for this reaction whereas CYP1A2, CYP2C9, CYP2C19 and CYP2D6 do not seem to be involved. This result was confirmed by using a monoclonal antibody against CYP3A4. Dextromethorphan was metabolized to dextrorphan in rat brain microsomes and was inhibited by quinidine and by a polyclonal antibody against CYP2D6. Only the addition of exogenous reductase allowed the measurement of this activity in human brain microsomes. Metabolites of the other substrates could not be detected, possibly due to an insufficiently sensitive method. It is concluded that cytochrome P450 activity in the brain is very low, but that psychotropic drugs could undergo a local cerebral metabolism which could have pharmacological and/or toxicological consequences.

Statistical approaches in the development of clinical practice guidelines from expert panels: the case of laminectomy in sciatica patients

BACKGROUND

Variation in expert opinion and lack of a systematic methodology hinder the development of reliable clinical practice guidelines. However standardized protocols have been defined to quantify, combine, and summarize expert judgments. In addition, statistical methods may help to outline guidelines based on simplified models of these judgments.

METHODS

To test this hypothesis, stepwise logistic regression (SLR) and classification tree pruning (CTP) were used to predict the results of two expert panels (USA 1992 and Switzerland 1995) on laminectomy in sciatica conditions. Both panels, using the RAND-UCLA explicit method, assessed whether the procedure would be inappropriate or of potential use in 720 case scenarios combining 7 relevant factors.

RESULTS

Laminectomy was rated as inappropriate in 60% and 70% of the scenarios by the US and Swiss panels, respectively. Either statistical method, in both panels, based its simplest model on the same 4 factors, as follows: imaging test results; disability; neurological findings; and conservative treatment trials (in decreasing order); the influence of 2 other factors, duration of pain and nerve root irritation, were only marginal. The correct classification rates of the models were 89% and 93% for SLR and 93% and 85% for CTP. Adopting the CTP US algorithm as a guideline would lead to consider performing laminectomy only in patients with imaging evidence of hernia, relatively severe disability, reflex abnormalities, and previous nonsurgical treatment. Adherence to the corresponding CTP Swiss algorithm would result in less restrictive conditions.

CONCLUSION

The statistical techniques proved as useful instruments to structure and simplify appropriateness criteria developed by expert panels and to outline parsimonious decision models for clinical practice.

Can the decision to operate be judged retrospectively? A study of medical records

OBJECTIVE

To examine the precision and completeness of information in medical records for evaluating the appropriateness of operative indications for lumbar disc surgery.

DESIGN

Retrospective review of records.

SETTING

University department of neurosurgery, Switzerland.

SUBJECT

100 patients.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Proportion of pre-defined, detailed appropriateness criteria present in the records. Proportion of cases that could unequivocally be classified as to the appropriateness of the indication for operation.

RESULTS

The criteria were present and precise for 52 of the items (range 9-90); present but imprecise for 38 of the items, and absent for 10. Because of this imprecision, the appropriateness of only 7 of the operative indications could be unequivocally assessed retrospectively.

CONCLUSION

Medical records are of limited use in assessing the appropriate management of care. The process of care should therefore be evaluated prospectively.

Inhibition of epidural fibrosis with ADCON-L: effect on clinical outcome one year following re-operation for recurrent lumbar radiculopathy

In a prospective multicenter study, 20 patients underwent re-operation for recurrent radiculopathy after lumbo-sacral discectomy, and were treated with ADCON-L (Adhesion Control in a Barrier Gel) to inhibit epidural fibrosis following secondary surgery. Outcomes after re-operation were assessed at six and 12 months using: Visual Analog Scales to measure radicular and back pain, straight leg raising exams, and self-assessment of activity-related radicular pain. Each parameter was compared to baseline values, obtained immediately prior to the re-operation. The long term clinical results at 12 months after re-operation (summarized below) demonstrate a significant improvement of all clinical parameters, and correlated with the results seen at six months. Radicular pain, measured when most severe, was reduced from an average pre-operative score of 8.1-3.7 (p < 0.005). The straight leg raising angle increased from an average pre-operative value of 41 degrees-67 degrees (p < 0.005). Activity-related pain mean score was 4.6, vs. 17.0 pre-operatively (p < 0.005). Low back pain, measured when most severe, was reduced from an average pre-operative score of 6.1 to 3.1 (p < 0.012). These clinical findings compare very favorably with data reported in the literature. There were no adverse events or complications related to the use of ADCON-L.

The assessment of appropriate indications for laminectomy

We have developed criteria to determine the appropriate indications for lumbar laminectomy, using the standard procedure developed at the RAND corporation and the University of California at Los Angeles (RAND-UCLA). A panel of five surgeons and four physicians individually assessed 1000 hypothetical cases of sciatica, back pain only, symptoms of spinal stenosis, spondylolisthesis, miscellaneous indications or the need for repeat laminectomy. For the first round each member of the panel used a scale ranging from 1 (extremely inappropriate) to 9 (extremely appropriate). After discussion and condensation of the results into three categories laminectomy was considered appropriate in 11% of the 1000 theoretical scenarios, equivocal in 26% and inappropriate in 63%. There was some variation between the six categories of malalignment, but full agreement in 64% of the hypothetical cases. We applied these criteria retrospectively to the records of 196 patients who had had surgical treatment for herniated discs in one Swiss University hospital. We found that 48% of the operations were for appropriate indications, 29% for equivocal reasons and that 23% were inappropriate. The RAND-UCLA method is a feasible, useful and coherent approach to the study of the indications for laminectomy and related procedures, providing a number of important insights. Our conclusions now require validation by carefully designed prospective clinical trials, such as those which are used for new medical techniques.

The assessment of appropriate indications for laminectomy

We have developed criteria to determine the appropriate indications for lumbar laminectomy, using the standard procedure developed at the RAND corporation and the University of California at Los Angeles (RAND-UCLA). A panel of five surgeons and four physicians individually assessed 1000 hypothetical cases of sciatica, back pain only, symptoms of spinal stenosis, spondylolisthesis, miscellaneous indications or the need for repeat laminectomy. For the first round each member of the panel used a scale ranging from 1 (extremely inappropriate) to 9 (extremely appropriate). After discussion and condensation of the results into three categories laminectomy was considered appropriate in 11% of the 1000 theoretical scenarios, equivocal in 26% and inappropriate in 63%. There was some variation between the six categories of malalignment, but full agreement in 64% of the hypothetical cases.

We applied these criteria retrospectively to the records of 196 patients who had had surgical treatment for herniated discs in one Swiss University hospital. We found that 48% of the operations were for appropriate indications, 29% for equivocal reasons and that 23% were inappropriate.

The RAND-UCLA method is a feasible, useful and coherent approach to the study of the indications for laminectomy and related procedures, providing a number of important insights. Our conclusions now require validation by carefully designed prospective clinical trials, such as those which are used for new medical techniques.

Long-term follow up of patients surgically treated by the far-lateral approach for foraminal and extraforaminal lumbar disc herniations

OBJECT

This study was undertaken to evaluate the long-term benefit in 202 patients who were surgically treated via a microsurgical far-lateral approach for foraminal or extraforaminal lumbar disc herniations.

METHODS

All patients underwent surgery at the authors' institute since 1987 and represented 6.5% of all lumbar spinal disc surgeries. There were 67 women and 135 men who ranged in age from 19 to 78 years (mean age 58 years). All patients had unilateral leg pain due to lumbar disc herniations into or lateral to the lateral interpedicular compartment. One patient underwent surgery at the L1-2 level, nine at L2-3, 48 at L3-4, 86 at L4-5, and 58 at the L5-S1 level. The mean follow-up period was 50 months (range 12-120 months). Outcome was defined as excellent (no pain), good (some back pain), fair (moderate radiculopathy), and poor (unchanged or worse) based on Macnab classification. Overall, excellent and good results were achieved in 62 (31%) and 85 (42%) patients, respectively, and fair and poor results in 40 (20%) and 15 (7%) patients, respectively. Of 11 recurrent disc herniations, four presented in an extreme-lateral position, five in a paramedian location, and two on the contralateral side. There were three minor complications related to surgery, seven general complications, and no case of spinal instability.

CONCLUSIONS

The far-lateral approach is a safe, effective procedure that avoids the risk of secondary spinal instability.

[The effect of position on intracranial pressure]

The question as to whether the head and trunk of neurosurgery patients should be elevated remains controversial. This question is particularly important when intracranial hypertension is present. Head up position may have beneficial effects on intracranial pressure (ICP) via changes in mean arterial pressure (MAP), airway pressure, central venous pressure and cerebro spinal fluid displacement. However, in some circumstances, head up position may decrease MAP which in turn will result in a paradoxical rise in ICP through autoregulation mechanisms. Therefore, the degree of head elevation has to be titrated by evaluating the most adequate cerebral perfusion pressure (CPP) for each patient by means of transcranial Doppler or measurement of jugular venous blood oxygen saturation. Head elevation above 30 degrees should be avoided in all cases. In most patients with intracranial hypertension, head and trunk elevation up to 30 degrees is useful in helping to decrease ICP, providing that a safe CPP of at least 70 mmHg or even 80 mmHg is maintained. Patients in poor haemodynamic conditions are best nursed flat. CPP is thus the most important factor in assessment and monitoring when considering head elevation in patients with increased ICP.

Clinical assessment of a novel antiadhesion barrier gel: prospective, randomized, multicenter, clinical trial of ADCON-L to inhibit postoperative peridural fibrosis and related symptoms after lumbar discectomy

A prospective, multicenter, randomized, double-blind, controlled study of ADCON-L Anti-Adhesion Barrier Gel (a medical device by Gliatech Inc, Cleveland, OH) was conducted in 298 patients undergoing first-time lumbar discectomy to evaluate the safety and effectiveness of ADCON-L in preventing postoperative peridural fibrosis and in improving patient clinical outcome. After lumbar discectomy, patients were randomized to receive either ADCON-L gel or nothing (control group) at the conclusion of the surgical procedure. Six months after surgery, peridural scar was evaluated by magnetic resonance imaging, and postoperative pain and straight-leg-raise angle were assessed. No statistically significant differences between the ADCON-L and control groups were observed in terms of adverse events or wound healing characteristics. ADCON-L gel was shown to be safe and to significantly inhibit peridural scar compared with the control group (P = 0.002). That peridural scarring was reduced with ADCON-L gel was further supported by direct visualization of scar tissue at reoperation in both groups. ADCON-L-treated patients had better clinical outcomes than did control patients. The incidence of activity-related pain was significantly reduced (P = 0.013), straight-leg-raise examination scores were significantly improved (P = 0.024 on the operative side and P = 0.015 on the nonoperative side), and ADCON-L reduced low back pain when it was most severe (P = 0.047) and at the end of the day (P = 0.044).

Cervical amyloidoma of C2. Case report and review of the literature

STUDY DESIGN

Second published report of a patient with amyloidoma of the upper cervical spine.

OBJECTIVES

To describe a patient with rare radiculopathy to alert other physicians to consider amyloid tumor as a differential diagnosis of locally destructive spine lesions.

SUMMARY OF BACKGROUND DATA

Localized amyloid tumor of the bone is a rare disease. Only seven cases of spine involvement have been reported. Appropriate tissue sampling is required to establish the diagnosis. Histopathologic examination shows pathognomonic apple-green birefringence under polarized light. When bone is involved with amyloid, it is most commonly associated with multiple myeloma or other plasma cell-dyscrasias.

METHOD

This case was described, and pertinent literature was reviewed.

RESULTS

The patient showed persistent neurologic improvement after transoral complete tumor removal, followed by a secondary posterior stabilization procedure using transarticular C1-C2 screws.

CONCLUSIONS

Amyloidomas are benign lesions with no associated documented risk for the development of plasmocytoma-related diseases. The clinical and radiographic manifestations of this lesion are nonspecific. A cure is possible with complete resection of the tumor and no adjuvant management procedures.

Unusual complications at iliac crest bone graft donor site: experience with two cases

OBJECTIVE AND IMPORTANCE

Two cases of fracture of the iliac crest after graft harvesting are presented. Only six such cases have been reported in the literature, although more than 100,000 such procedures are performed each year in the United States alone. This complication adds to the morbidity of the procedure for which the graft is taken. Its avoidance by an appropriate harvesting technique will reduce patient disability and shorten hospital stay.

CLINICAL PRESENTATION

A 56-year-old man who worked as a mechanic underwent anterior cervical discectomies and fusion at C5-C6 and C6-C7 for spondylotic radiculopathies. Another patient, a 48-year-old man, required mandibular reconstruction for squamous cell carcinoma. Both grafts were harvested from the iliac crest using osteotomies. On the 9th and 3rd postoperative days, respectively, each patient developed groin pain while walking, associated with marked tenderness over the graft donor sites. X-rays showed fractured iliac crests.

INTERVENTION

Apart from bed rest for pain, no specific treatment was required.

CONCLUSION

The use of the osteotome weakens the iliac crest, leading to stress fractures caused by the pulling action of the attached muscles. To prevent this from happening, we recommend the use of the oscillating saw, leaving a 3-cm spike of iliac crest anteriorly. Nevertheless, this complication has a good long-term outcome.