Growth and Resorption of Chronic Subdural Hematomas: Gardner, Weir, and the Osmotic Hypothesis Revisited.

BACKGROUND: To explain why some chronic subdural hematomas (CSDHs) grow and/or resorb, a physically decreasing outer membrane (OM) surface area (SA) to CSDH volume (V) ratio has been reexplored, and a critical CSDH size inferred (OM SA ≈ V). Gardner showed that since CSDH protein exceeded cerebrospinal fluid (CSF) protein, CSF→CSDH osmosis occurred across a semipermeable inner membrane (n = 1). By contrast, Zollinger and Gross demonstrated that serum→CSDH osmosis could also occur across the OM (n = 1). Notably, Weir refuted Zollinger and Gross by finding equal CSDH and serum total protein (n = 20); however, Weir did not refute Gardner. Although all extant mechanisms, especially rehemorrhages, explain CSDH growth, only OM SA ≥ V simultaneously permits resorption. We aimed to reevaluate the osmotic hypothesis. METHODS: Paired serum and CSDH samples were measured in a prospective cohort. RESULTS: Results were consecutively obtained in 116 patients (87 men; mean age, 73 ± 13 years). Serum osmolality and CSDH osmolality were similar (285.70 ± 7.99 vs. 283.85 ± 7.52 mmol/kg, respectively; P = 0.11) and significantly correlated (r = 0.75, P < 0.0001). Serum total protein significantly exceeded CSDH total protein (66.6 ± 6.8 vs. 43.68 ± 20.24 g/L, P < 0.0001) as did serum albumin (35.62 ± 4.46 vs. 30.85 ± 8.5 g/L, P < 0.0001) and serum total globulins (31.5 ± 6 vs. 18.6 ± 11.4 g/L, P < 0.0001). Serum and CSDH proteins were not correlated (total protein: r = 0.003; albumin: r = 0.08; globulins: r = 0.21). CONCLUSIONS: Only crystalloids equilibrated. CSDH colloids were significantly decreased. CSDH dilution or colloidal flocculation is implied. CSDH dilution (by CSF→CSDH inner membrane [IM] osmosis or OM transudation/exudation) could favor CSDH growth, as would repeated OM hemorrhages. Contrariwise, isolated colloidal flocculation could favor CSDH shrinkage by OM CSDH→serum osmosis. The latter may result in OM SA ≥ V favorable for ultimate resolution. Our results refute Weir and Zollinger and Gross, but not Gardner. Osmotic gradients simultaneously exist for both CSDH growth and resorption. Each equilibrium could depend on each gradient relative to each IM/OM semipermeability.

Early Postoperative Morbidity After Chronic Subdural Hematoma: Predictive Usefulness of the Physiological and Operative Severity Score for Enumeration of Mortality and Morbidity, American College of Surgeons National Surgical Quality Improvement Program, and American Society of Anesthesiologists Grade in a Prospective Cohort.

BACKGROUND: Although chronic subdural hematoma (CSDH) is generally benign, long-term survival (LTS) after CSDH is poor in a significant subgroup. This dichotomy has been compared to fractured neck of femur. However, although early postoperative mortality (within 30 days of CSDH) is well recorded with CSDH and similar to fractured neck of femur (4%-8%), scant accurate data exist regarding early postoperative morbidity (POMB). POMB, which prolongs length of stay (LOS) after major nonneurosurgery, is associated with decreased LTS. One recent CSDH study suggested a POMB standard of 10% i.e., notably less than with fractured neck of femur (45%). METHODS: POMB was recorded in a novel prospective single-center cohort after CSDH. The POSSUM (Physiological and Operative Severity Score for Enumeration of Mortality and Morbidity), American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) score, and American Society of Anesthesiologists (ASA) grade were assessed as tools for potentially predicting POMB. Receiver operating characteristic (ROC) curves were calculated. RESULTS: Early postoperative mortality (within 30 days of CSDH) occurred in 3 of 114 patients (3%). Seventy-one POMB events occurred in 54 of 114 patients (47%), with 27 of 54 (50%) having a Clavien-Dindo grade ≥2. Most POMB was neurologic (n = 47/71, 66%). Age (P = 0.01), Glasgow Coma Scale (GCS) score (P = 0.001), Markwalder grade (P = 0.01), hypertension (P = 0.047), and/or ≥1 preexistent comorbidity (P = 0.041) were predictive. LOS (P = 0.01) and discharge modified Rankin Scale score (P < 0.001) were significantly associated. Predicted and observed POMB with POSSUM were significantly disparate (χ2 = 15.23; P = 0.001): POSSUM area under ROC (AUROC = 0.611) was also nondiscriminatory. ACS-NSQIP (χ2 = 18.51; P < 0.001; AUROC = 0.629) and ASA grades (P = 0.25) were also nonpredictive. CONCLUSIONS: POMB was frequently disabling, mostly neurologic, and as frequent and diverse as with fractured neck of femur. POMB was significantly correlated with LOS and discharge modified Rankin Scale score. Surprisingly, POSSUM, ACS-NSQIP, and ASA grades were not predictive and would not aid consent. Simple parameters (age, Glasgow Coma Scale, Markwalder grade, hypertension, and/or ≥1 other comorbidity) were instead predictive. Longitudinal follow-up will determine whether POMB affects LTS. CSDH, like fractured neck of femur, is distinct.

Management of Giant Calcified Thoracic Disks and Description of the Trench Vertebrectomy Technique.

STUDY DESIGN: Case series and review of the literature. OBJECTIVE: To review the management of giant calcified disks in our large cohort and compare with the existing literature. We discuss our surgical technique. METHODS: Twenty-nine cases of herniated thoracic disk between 2000 and 2013 were reviewed. Eighteen patients were identified as having giant calcified thoracic disks, defined as diffusely calcified disks occupying at least 40% of the spinal canal. Demographic data was collected in addition to presentation, imaging findings, operative details, and outcomes using the modified Japanese Orthopaedic Association (mJOA) scale. RESULTS: Giant calcified thoracic disks (GCTDs) are unique clinical entities that require special neurosurgical consideration owing to significant (≥40%) involvement of the spinal canal and compression of the spinal cord, often leading to myelopathy. The median age at diagnosis was 51.2 years (range 37 to 70) with the mean duration of presenting symptoms being 9.9 months (range 2 weeks to 3 years). Seventeen (94.4%) patients presented with at least one sign of myelopathy (hyperreflexia, hypertonia, bladder or bowel dysfunction) with the remaining 1 (5.6%) patient presenting with symptoms in keeping with radiculopathy. Thoracotomy was performed on 17 (94.4%) patients, and 1 (5.6%) patient had a costotransverse approach. Mean follow-up was 19.8 months (range 7 months to 2 years). mJOA score improved in 15 (83.3%) patients. mJOA scores in the other patients remained stable. CONCLUSIONS: GCTDs are difficult neurosurgical challenges owing to their size, degree of spinal cord compression, and consistency. We recommend a trench vertebrectomy via a thoracotomy in their surgical management. This procedure safely allows the identification of normal dura on either side of the compressed segment prior to performing a diskectomy. Excellent fusion rates were achieved with insertion of rib head autograft in the trench.

Outcome of microsurgical excision of unruptured brain arteriovenous malformations in ARUBA-eligible patients.

OBJECTIVES: To determine the outcome of microsurgical excision of selected unruptured brain arteriovenous malformations (AVMs), and to compare the results with those of the ARUBA trial. METHODS: Prospective data collection for all patients undergoing microsurgical excision of unruptured brain AVMs by two neurovascular surgeons. Outcome measures similar to those assessed in the ARUBA trial (death and stroke) as well as modified Rankin scores (mRS) at 6 months were assessed. RESULTS: Between September 2004 and September 2014, 45 patients with unruptured brain AVMs underwent microsurgical excision. 11 patients (eight children and three with mRS >2 at presentation) were excluded to match ARUBA eligibility criteria. 34 patients were included in this study. AVM characteristics closely matched those in the ARUBA trial with 70.5% Spetzler-Martin (SM) grade I or II AVMs, 68% AVM size <3 cm. However, compared to ARUBA, a larger proportion of our patients presented with seizures, and a lower proportion with headaches. 8(23%) had preoperative embolization. There were no deaths and no strokes (as defined in ARUBA). 5 (14.7%) had permanent neurological deficit related to surgery within/near eloquent cortex. At 6 months follow-up, 32 (94%) had mRS score of 0-1. Two (6%) had mRS 2 and none had mRS> 2. Postoperative digital DSA confirmed complete AVM excision in all cases. None of the patients have suffered intracranial hemorrhage during the follow-up period of 6-126 (median 69) months. CONCLUSIONS: Microsurgical excision of unruptured brain AVMs can be performed with low morbidity in selected cases. Our study has limitations particularly the small number of patients with selected AVMs for microsurgical excision. However, our results suggest that ARUBA results may not be applicable to microsurgical excision when cases are appropriately selected for this treatment modality.