Firearm-Related Traumatic Brain Injuries in Adults: A Scoping Review

BACKGROUND AND OBJECTIVES

Firearm-related traumatic brain injury (TBI) has emerged as a significant public health issue in the United States, coinciding with a rapid increase in gun-related deaths. This scoping review aims to update our understanding of firearm-related TBI in adult populations.

METHODS

A comprehensive search of 6 online databases yielded 22 studies that met the inclusion criteria. The reviewed studies predominantly focused on young adult men who were victims of assault, although other vulnerable populations were also affected.

RESULTS

Key factors in evaluating patients with firearm-related TBI included low Glasgow Coma Scale scores, central nervous system involvement, hypotension, and coagulopathies at presentation. Poor outcomes in firearm-related TBIs were influenced by various factors, including the location and trajectory of the gunshot wound, hypercoagulability, hemodynamic instability, insurance status, and specific clinical findings at hospital admission.

CONCLUSION

Proposed interventions aimed to reduce the incidence and mortality of penetrating TBIs, including medical interventions such as coagulopathy reversal and changes to prehospital stabilization procedures. However, further research is needed to demonstrate the effectiveness of these interventions. The findings of this scoping review hope to inform future policy research, advocacy efforts, and the training of neurosurgeons and other treating clinicians in the management of firearm-related TBI.

Cerebral microdialysis and glucopenia in traumatic brain injury: A review

Traditionally, intracranial pressure (ICP) and partial brain tissue oxygenation (PbtO₂) have been the primary invasive intracranial measurements used to guide management in patients with severe traumatic brain injury (TBI). After injury however, the brain develops an increased metabolic demand which may require an increment in the oxidative metabolism of glucose. Simultaneously, metabolic, and electrical dysfunction can lead to an inability to meet these demands, even in the absence of ischemia or increased intracranial pressure. Cerebral microdialysis provides the ability to accurately measure local concentrations of various solutes including lactate, pyruvate, glycerol and glucose. Experimental and clinical data demonstrate that such measurements of cellular metabolism can yield critical missing information about a patient's physiologic state and help limit secondary damage. Glucose management in traumatic brain injury is still an unresolved question. As cerebral glucose metabolism may be uncoupled from systemic glucose levels due to the metabolic dysfunction, measurement of cerebral extracellular glucose concentrations could provide more predictive information and prove to be a better biomarker to avoid secondary injury of at-risk brain tissue. Based on data obtained from cerebral microdialysis, specific interventions such as ICP-directed therapy, blood glucose increment, seizure control, and/or brain oxygen optimization can be instituted to minimize or prevent secondary insults. Thus, microdialysis measurements of parenchymal metabolic function provides clinically valuable information that cannot be obtained by other monitoring adjuncts in the standard ICU setting.

Neurolymphomatosis of the brachial plexus from atypical primary central nervous system lymphoma lesions: A case report and review of the literature

Background:

Primary central nervous system lymphoma (PCNSL) is an aggressive and extranodal non-Hodgkin lymphoma limited to the neuroaxis. In immunocompetent individuals, PCNSL is more common in older adults and lacks the association with the Epstein–Barr virus found in individuals with AIDS-associated PCNSL. Because the clinical presentation and radiographic findings of PCNSL are highly variable, stereotactic brain biopsy is typically required for definitive diagnosis. High-dose methotrexate, in combination with other chemotherapeutic agents with or without whole brain radiation, is the mainstay of treatment.

Case Description:

A 70-year-old HIV-negative woman presented with confusion, acute flaccid left arm weakness, and left hand numbness. Head computed tomography without contrast demonstrated a 1 cm hyperdense round lesion in the suprasellar cistern that prompted further evaluation. Gadolinium-enhanced brain magnetic resonance imaging demonstrated enhancing lesions with heterogeneous signal intensity in the suprasellar, pineal, and right periatrial regions that did not explain the limb weakness and numbness. Serum and cerebrospinal fluid (CSF) studies were unrevealing, and a diagnosis of PCNSL was made following stereotactic biopsy. The patient’s liver cirrhosis precluded chemotherapy, but treatment with whole-brain radiation was pursued.

Conclusion:

The myriad clinical presentations and insidious course of PCNSL contribute to diagnostic difficulties, delays in treatment, and poor outcomes. Stereotactic brain biopsy is the primary method of PCNSL diagnosis since malignant cells are typically not detected in CSF. PCNSL should be considered in the differential diagnosis when immunocompetent elderly patients present with multiple intracranial lesions, even in the presence of lower motor neuron findings.

The impact of a night float system on operative experience in neurosurgery residency

OBJECTIVE

Since the Accreditation Council for Graduate Medical Education (ACGME) implemented duty-hour restrictions in 2003, many residency programs have adopted a night float system to comply with time constraints. However, some surgical subspecialities have been concerned that use of a night float system deprives residents of operative experience. In this study, the authors describe their training program's transition to a night float system and its impact on resident operative experience.

METHODS

The authors conducted a single-program study of resident surgical case volume before and after implementing the night float system at 3 of their 5 hospitals from 2014 to 2020. The authors obtained surgical case numbers from the ACGME case log database.

RESULTS

Junior residents received a concentrated educational experience, whereas senior residents saw a significant decrease from 112 calls/year to 17. Logged cases significantly increased after implementation of the night float system (8846 vs 10,547, p = 0.04), whereas cases at non-night float hospitals remained the same. This increase was concurrent with an increase in hospital cases. This difference was mainly driven by senior resident cases (p = 0.010), as junior and chief residents did not show significant differences in logged cases (p > 0.40). Lead resident cases increased significantly after implementation of the night float system (6852 vs 8860, p = 0.04). When normalized for increased hospital cases, resident case increases were not statistically significant.

CONCLUSIONS

Transitioning to a night float call system at the authors' institution increased overall resident operative cases, particularly for lead resident surgeons. Based on the results of this study, the authors recommend the use of a night float call system to consolidate night calls, which increases junior resident-level educational opportunities and senior resident cases.

Racial and Socioeconomic Disparities in Patients With Meningioma: A Retrospective Cohort Study

BACKGROUND

Meningiomas are the most common intracranial neoplasms. Although genomic analysis has helped elucidate differences in survival, there is evidence that racial disparities may influence outcomes. African Americans have a higher incidence of meningiomas and poorer survival outcomes. The etiology of these disparities remains unclear, but may include a combination of pathophysiology and other factors.

OBJECTIVE

To determine factors that contribute to different clinical outcomes in racial populations.

METHODS

We retrospectively reviewed 305 patients who underwent resection for meningiomas at a single tertiary care facility. We used descriptive statistics and univariate, multivariable, and Kaplan-Meier analyses to study clinical, radiographical, and histopathological differences.

RESULTS

Minority patients were more likely to present through the emergency department than an outpatient clinic (P < .0001). They were more likely to present with more advanced clinical symptoms with lower Karnofsky Performance scores, more frequently had peritumoral edema (P = .0031), and experienced longer postoperative stays in the hospital (P = .0053), and African-American patients had higher hospitalization costs (P = .046) and were more likely to be publicly insured. Extent of resection was an independent predictor of recurrence freedom (P = .039). Presentation in clinic setting trended toward an association with recurrence-free survival (P = .055). We observed no significant difference in gross total resection rates, postoperative recurrence, or recurrence-free survival.

CONCLUSION

Minority patients are more likely to present with severe symptoms, require longer perioperative hospitalization, and generate higher hospitalization costs. This may be due to socioeconomic factors that affect access to health care. Targeting barriers to access, especially to subspecialty care, may facilitate more appropriate and timely diagnosis, thereby improving patient care and outcomes.

Intracranial Solitary Fibrous Tumor of the Skull Base: 2 Cases and Systematic Review of the Literature

BACKGROUND

Intracranial solitary fibrous tumors (ISFTs) are rare neoplasms of mesenchymal origin that originate from the meninges. ISFTs of the skull base can be challenging to treat, as resection can be complicated by skull base anatomy. We present 2 cases of ISFT, the first manifesting with compressive cranial neuropathy from Meckel cave involvement and the second a posterior fossa lesion causing symptomatic hydrocephalus.

METHODS

A systematic review was performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The PubMed database was queried with title/abstract keywords "intracranial," "solitary fibrous tumor," "hemangiopericytoma," "SFT," and "HPC." Search results were reviewed to exclude cases not involving the skull base. References from all selected articles were reviewed for potential additional cases. Patient demographic and clinical data from 58 identified skull base cases were collected for qualitative synthesis.

RESULTS

Visual disturbances were the most common presenting symptom (30 cases, 52%) followed by headache (22 cases, 38%). The most common site of involvement was the sellar/parasellar region (18 cases, 31%) followed by middle fossa/temporal bone (14 cases, 24%). Resection was performed in 55 cases; gross total resection was reported in 26 cases (45%) and subtotal resection was reported in 21 cases (36%). Tumor recurrence was documented in 15 cases (26%) with median and mean follow-up periods of 16 and 29.9 months, respectively.

CONCLUSIONS

We discuss presentation, imaging, histopathology, and management considerations for ISFTs while highlighting the potentially complex nature of skull base lesions and need for multidisciplinary approach to treatment.

Morbidity and mortality associated with hypernatremia in patients with severe traumatic brain injury

OBJECTIVE

Hypernatremia is independently associated with increased mortality in critically ill patients. Few studies have evaluated the impact of hypernatremia on early mortality in patients with severe traumatic brain injury (TBI) treated in a neurocritical care unit.

METHODS

A retrospective review of patients with severe TBI (admission Glasgow Coma Scale score ≤ 8) treated in a single neurocritical care unit between 1986 and 2012 was performed. Patients with at least 3 serum sodium values were selected for the study. Patients with diabetes insipidus and those with hypernatremia on admission were excluded. The highest serum sodium level during the hospital stay was recorded, and hypernatremia was classified as none (≤ 150 mEq/L), mild (151–155 mEq/L), moderate (156–160 mEq/L), and severe (> 160 mEq/L). Multivariate Cox regression analysis was performed to determine independent predictors of early mortality.

RESULTS

A total of 588 patients with severe TBI were studied. The median number of serum sodium measurements for patients in this study was 17 (range 3–190). No hypernatremia was seen in 371 patients (63.1%), mild hypernatremia in 77 patients (13.1%), moderate hypernatremia in 50 patients (8.5%), and severe hypernatremia in 90 patients (15.3%). Hypernatremia was detected within the 1st week of admission in 79.3% of patients (n = 172), with the majority of patients (46%) being diagnosed within 72 hours after admission. Acute kidney injury, defined as a rise in creatinine of ≥ 0.3 mg/dl, was observed in 162 patients (27.6%) and was significantly associated with the degree of hypernatremia (p < 0.001). At discharge, 148 patients (25.2%) had died. Hypernatremia was a significant independent predictor of mortality (hazard ratios for mild: 3.4, moderate: 4.4, and severe: 8.4; p < 0.001). Survival analysis showed significantly lower survival rates for patients with greater degrees of hypernatremia (log-rank test, p < 0.001).

CONCLUSIONS

Hypernatremia after admission in patients with severe TBI was independently associated with greater risk of early mortality. In addition to severe hypernatremia, mild and moderate hypernatremia were significantly associated with increased early mortality in patients with severe TBI.

Quantitative cerebral blood flow using xenon-enhanced CT after decompressive craniectomy in traumatic brain injury

OBJECTIVE Few studies have reported on changes in quantitative cerebral blood flow (CBF) after decompressive craniectomy and the impact of these measures on clinical outcome. The aim of the present study was to evaluate global and regional CBF patterns in relation to cerebral hemodynamic parameters in patients after decompressive craniectomy for traumatic brain injury (TBI). METHODS The authors studied clinical and imaging data of patients who underwent xenon-enhanced CT (XeCT) CBF studies after decompressive craniectomy for evacuation of a mass lesion and/or to relieve intractable intracranial hypertension. Cerebral hemodynamic parameters prior to decompressive craniectomy and at the time of the XeCT CBF study were recorded. Global and regional CBF after decompressive craniectomy was measured using XeCT. Regional cortical CBF was measured under the craniectomy defect as well as for each cerebral hemisphere. Associations between CBF, cerebral hemodynamics, and early clinical outcome were assessed. RESULTS Twenty-seven patients were included in this study. The majority of patients (88.9%) had an initial Glasgow Coma Scale score ≤ 8. The median time between injury and decompressive surgery was 9 hours. Primary decompressive surgery (within 24 hours) was performed in the majority of patients (n = 18, 66.7%). Six patients had died by the time of discharge. XeCT CBF studies were performed a median of 51 hours after decompressive surgery. The mean global CBF after decompressive craniectomy was 49.9 ± 21.3 ml/100 g/min. The mean cortical CBF under the craniectomy defect was 46.0 ± 21.7 ml/100 g/min. Patients who were dead at discharge had significantly lower postcraniectomy CBF under the craniectomy defect (30.1 ± 22.9 vs 50.6 ± 19.6 ml/100 g/min; p = 0.039). These patients also had lower global CBF (36.7 ± 23.4 vs 53.7 ± 19.7 ml/100 g/min; p = 0.09), as well as lower CBF for the ipsilateral (33.3 ± 27.2 vs 51.8 ± 19.7 ml/100 g/min; p = 0.07) and contralateral (36.7 ± 19.2 vs 55.2 ± 21.9 ml/100 g/min; p = 0.08) hemispheres, but these differences were not statistically significant. The patients who died also had significantly lower cerebral perfusion pressure (52 ± 17.4 vs 75.3 ± 10.9 mm Hg; p = 0.001). CONCLUSIONS In the presence of global hypoperfusion, regional cerebral hypoperfusion under the craniectomy defect is associated with early mortality in patients with TBI. Further study is needed to determine the value of incorporating CBF studies into clinical decision making for severe traumatic brain injury.

Clinical characteristics and temporal profile of recovery in patients with favorable outcomes at 6 months after severe traumatic brain injury

OBJECTIVE Early withdrawal of life-sustaining treatment due to expected poor prognosis is responsible for the majority of in-house deaths in severe traumatic brain injury (TBI). With increased focus on the decision and timing of withdrawal of care in patients with severe TBI, data on early neurological recovery in patients with a favorable outcome is needed to guide physicians and families. METHODS The authors reviewed prospectively collected data obtained in 1241 patients with head injury who were treated between 1986 and 2012. Patients with severe TBI, motor Glasgow Coma Scale (mGCS) score < 6 on admission, and those who had favorable outcomes (Glasgow Outcome Scale [GOS] score of 4 or 5, indicating moderate disability or good recovery) at 6 months were selected. Baseline demographic, clinical, and imaging data were analyzed. The time from injury to the first record of following commands (mGCS score of 6) after injury was recorded. The temporal profile of GOS scores from discharge to 6 months after the injury was also assessed. RESULTS The authors studied 218 patients (183 male and 35 female) with a mean age of 28.9 ± 11.2 years. The majority of patients were able to follow commands (mGCS score of 6) within the 1st week after injury (71.4%), with the highest percentage of patients in this group recovering on Day 1 (28.6%). Recovery to the point of following commands beyond 2 weeks after the injury was seen in 14.8% of patients, who experienced significantly longer durations of intracranial pressure monitoring (p = 0.001) and neuromuscular blockade (p < 0.001). In comparison with patients with moderate disability, patients with good recovery had a higher initial GCS score (p = 0.01), lower incidence of anisocoria at admission (p = 0.048), and a shorter ICU stay (p < 0.001) and total hospital stay (p < 0.001). There was considerable improvement in GOS scores from discharge to follow-up at 6 months. CONCLUSIONS Up to 15% of patients with a favorable outcome after severe TBI may begin to follow commands beyond 2 weeks after the injury. These data caution against early withdrawal of life-sustaining treatment in patients with severe TBI.

Factors associated with shunt-dependent hydrocephalus after decompressive craniectomy for traumatic brain injury

OBJECTIVE Posttraumatic hydrocephalus (PTH) affects 11.9%-36% of patients undergoing decompressive craniectomy (DC) and is an important cause of morbidity after traumatic brain injury (TBI). Early diagnosis and treatment of PTH can prevent further neurological compromise in patients who are recovering from TBI. There is limited data on predictors of shunting for PTH after DC for TBI. METHODS Prospectively collected data from the erythropoietin severe TBI randomized controlled trial were studied. Demographic, clinical, and imaging data were analyzed for enrolled patients who underwent a DC. All head CT scans during admission were reviewed and assessed for PTH by the Gudeman criteria or the modified Frontal Horn Index ≥ 33%. The presence of subdural hygromas was categorized as unilateral/bilateral hemispheric or interhemispheric. Using L1-regularized logistic regression to select variables, a multiple logistic regression model was created with ventriculoperitoneal shunting as the binary outcome. Statistical significance was set at p < 0.05. RESULTS A total of 60 patients who underwent DC were studied. Fifteen patients (25%) underwent placement of a ventriculoperitoneal shunt for PTH. The majority of patients underwent unilateral decompressive hemicraniectomy (n = 46, 77%). Seven patients (12%) underwent bifrontal DC. Unilateral and bilateral hemispheric hygromas were noted in 31 (52%) and 7 (11%) patients, respectively. Interhemispheric hygromas were observed in 19 patients (32%). The mean duration from injury to first CT scan showing hemispheric subdural hygroma and interhemispheric hygroma was 7.9 ± 6.5 days and 14.9 ± 11.7 days, respectively. The median duration from injury to shunt placement was 43.7 days. Multivariate analysis showed that the presence of interhemispheric hygroma (OR 63.6, p = 0.001) and younger age (OR 0.78, p = 0.009) were significantly associated with the need for a shunt after DC. CONCLUSIONS The presence of interhemispheric subdural hygromas and younger age were associated with shunt-dependent hydrocephalus after DC in patients with severe TBI.

Management of Acute Unilateral Nondisplaced Subaxial Cervical Facet Fractures

BACKGROUND

Few studies have focused on the management of patients with nondisplaced cervical facet fractures.

OBJECTIVE

To determine the rate of successful nonoperative management and risk factors for instability in patients with acute traumatic, unilateral, nondisplaced cervical facet fractures.

METHODS

We reviewed patients with single or multilevel unilateral nondisplaced or minimally displaced subaxial cervical facet fractures between 2008 and 2014. Facet fractures were classified as type A1 fractures: superior facet fracture of caudal vertebra; type A2: inferior facet fracture of rostral vertebral; and type A3: floating lateral mass (fracture of pedicle and vertical laminar fracture). All patients were given a trial of nonoperative management with external immobilization using a hard cervical collar. Follow-up clinical data and cervical spine radiographs were analyzed to determine factors associated with instability.

RESULTS

Thirty-five patients (34 males, mean age 40.2 ± 2.4 yr) were reviewed. The mean follow-up duration was 2.7 ± 0.4 mo. The distribution of fracture types was type A1 (n = 15), type A2 (n = 4), type A3 (n = 5), type A1 and A2 fractures (n = 10), and type A1 and A3 fractures (n = 1). Nonoperative management was successful in 29 patients (82.9%), and 6 patients developed instability requiring surgery. All patients who failed nonoperative management had associated injuries suggesting a more severe mechanism of injury. No significant association was found between the type of facet fracture and outcome (Fisher's exact test, P = .18).

CONCLUSION

In our series, more than 80% of the patients with unilateral, nondisplaced cervical facet fractures underwent successful nonoperative management in the short term.

Occipital Artery Pseudoaneurysm After Posterior Fossa Craniotomy

BACKGROUND

Pseudoaneurysms of scalp arteries have been reported in rare cases after iatrogenic injury; however, they are far more commonly seen after traumatic injuries. They are usually associated with the superficial temporal artery; however, there have been a few reports of psuedoaneurysms of the occipital artery (OA).

CASE DESCRIPTION

We present a unique case of an OA pseudoaneurysm presenting with delayed postoperative hemorrhage after a retrosigmoid craniotomy. The pseudoaneurysm was treated by coil embolization.

CONCLUSIONS

The patient recovered fully after endovascular embolization. Other treatment options for pseudoaneurysms of facial, temporal, and scalp arteries include surgical clipping/trapping with excision, Hunterian ligation, or direct compression. Pseudoaneurysms of extracranial scalp arteries are rare and most often caused by traumatic compression of the artery against a bony ridge. Despite their rarity, pseudoaneurysms secondary to iatrogenic injury to extracranial arteries should be considered in the differential diagnosis in patients presenting with delayed incisional pain, redness, and swelling.

Clinical application of near-infrared spectroscopy in patients with traumatic brain injury: a review of the progress of the field

Near-infrared spectroscopy (NIRS) is a technique by which the interaction between light in the near-infrared spectrum and matter can be quantitatively measured to provide information about the particular chromophore. Study into the clinical application of NIRS for traumatic brain injury (TBI) began in the 1990s with early reports of the ability to detect intracranial hematomas using NIRS. We highlight the advances in clinical applications of NIRS over the past two decades as they relate to TBI. We discuss recent studies evaluating NIRS techniques for intracranial hematoma detection, followed by the clinical application of NIRS in intracranial pressure and brain oxygenation measurement, and conclude with a summary of potential future uses of NIRS in TBI patient management.

Intracranial Hypertension Caused by Occipital Calvarial Hemangioma: Case Report

BACKGROUND

Primary intraosseous calvarial hemangiomas (PICHs) are generally rare and predominate (3:1) in women. Occurrence in the frontal and parietal bones is most common, but involvement of the occipital bone is exceedingly rare, representing 3 of 125 cases in a series of PICHs studied by Heckl et al. in 2000. Histopathology establishes the diagnosis of cavernous hemangioma, which represents the most common subtype of intraosseous hemangiomas. Others include sclerosing, cellular, and capillary. When they do occur in the calvarium, they are most often asymptomatic and discovered incidentally or due to a palpable defect in the skull.

CASE DESCRIPTION

In this case, a calvarial hemangioma was found to be the cause of elevated intracranial pressure in a 35-year-old woman. Resection of the hemangioma and reconstruction of the calvarium provided a complete cure for her symptoms.

CONCLUSIONS

Primary intraosseous hemangiomas are rarely symptomatic but must be considered in the differential for calvarial lesions as part of safe surgical planning. Formulating an accurate differential diagnosis by acquiring proper imaging studies and specifically recognizing the classical "starburst" appearance, as well as considering the highly vascular pathology to avoid excess blood loss, is important. This unique case of a hemangioma-induced venous sinus compression and subsequent elevated intracranial pressure illustrates that hemangiomas can arise from any part of the calvarium and cause a wide variety of clinical symptoms.

Progressive hemorrhagic injury after severe traumatic brain injury: effect of hemoglobin transfusion thresholds

OBJECT There is limited literature available to guide transfusion practices for patients with severe traumatic brain injury (TBI). Recent studies have shown that maintaining a higher hemoglobin threshold after severe TBI offers no clinical benefit. The present study aimed to determine if a higher transfusion threshold was independently associated with an increased risk of progressive hemorrhagic injury (PHI), thereby contributing to higher rates of morbidity and mortality. METHODS The authors performed a secondary analysis of data obtained from a recently performed randomized clinical trial studying the effects of erythropoietin and blood transfusions on neurological recovery after severe TBI. Assigned hemoglobin thresholds (10 g/dl vs 7 g/dl) were maintained with packed red blood cell transfusions during the acute phase after injury. PHI was defined as the presence of new or enlarging intracranial hematomas on CT as long as 10 days after injury. A severe PHI was defined as an event that required an escalation of medical management or surgical intervention. Clinical and imaging parameters and transfusion thresholds were used in a multivariate Cox regression analysis to identify independent risk factors for PHI. RESULTS Among 200 patients enrolled in the trial, PHI was detected in 61 patients (30.5%). The majority of patients with PHI had a new, delayed contusion (n = 29) or an increase in contusion size (n = 15). The mean time interval between injury and identification of PHI was 17.2 ± 15.8 hours. The adjusted risk of severe PHI was 2.3 times higher for patients with a transfusion threshold of 10 g/dl (95% confidence interval 1.1-4.7; p = 0.02). Diffuse brain injury was associated with a lower risk of PHI events, whereas higher initial intracranial pressure increased the risk of PHI (p < 0.001). PHI was associated with a longer median length of stay in the intensive care unit (18.3 vs 14.4 days, respectively; p = 0.04) and poorer Glasgow Outcome Scale scores (42.9% vs 25.5%, respectively; p = 0.02) at 6 months. CONCLUSIONS A higher transfusion threshold of 10 g/dl after severe TBI increased the risk of severe PHI events. These results indicate the potential adverse effect of using a higher hemoglobin transfusion threshold after severe TBI.

Shunting in cryptococcal meningitis

OBJECT Patients with cryptococcal meningitis often develop symptomatic intracranial hypertension. The need for permanent CSF diversion in these cases remains unclear. METHODS Cases of cryptococcal meningitis over a 5-year period were reviewed from a single, large teaching hospital. Sources of identification included ICD-9 codes, operative logs, and microscopy laboratory records. RESULTS Fifty cases of cryptococcal meningitis were identified. Ninety-eight percent (49/50) of patients were HIV positive. Opening pressure on initial lumbar puncture diagnosing cryptococcal meningitis was elevated (> 25 cm H2O) in 33 cases and normal (≤ 25 cm H2O) in 17 cases. Thirty-eight patients ultimately developed elevated opening pressure over a follow-up period ranging from weeks to years. Serial lumbar punctures for relief of intracranial hypertension were performed in 29 cases. Thirteen of these patients ultimately had shunting procedures performed after failing to improve clinically. Two factors were significantly associated with the need for shunting: patients undergoing shunt placement were more likely to be women (5/13 vs 0/16; p = 0.01) and to have a pattern of increasing CSF cryptococcal antigen (10/13 vs 3/16 cases; p = 0.003). All patients re-presenting with mycological relapse either underwent or were offered shunt placement. CONCLUSIONS Neurosurgeons are often asked to consider CSF diversion in cases of cryptococcal meningitis complicated by intracranial hypertension. Most patients do well with serial lumbar punctures combined with antifungal therapy. When required, shunting generally provided sustained relief from intracranial hypertension symptoms. Ventriculoperitoneal shunts are the favored method of diversion. To the authors' knowledge, the present study is the largest series on diversionary shunts in primarily HIV-positive patients with this problem.

Predictors of outcome in civilians with gunshot wounds to the head upon presentation

OBJECT

Prediction of outcome from initial presentation after a gunshot wound to the head (GSWH) is essential to further clinical decision making. The authors' goals are to report the survival and functional outcomes of these patients, to identify prognostic factors, and to propose a scoring system that can predict their outcome.

METHODS

The records of 199 patients admitted with a GSWH with dural penetration between 1990 and 2008 were retrospectively reviewed. The inclusion criterion was a CT scan available for review. Patients declared brain dead on presentation were excluded, which yielded a series of 119 patients. Statistical analysis was performed using a logistic regression model.

RESULTS

Fifty-eight (49%) of the 119 patients died. Twenty-three patients (19%) had a favorable outcome defined as a 6-month Glasgow Outcome Scale (GOS) score of moderate disability or good recovery, 35 (29%) had a poor outcome (GOS of persistent vegetative state or severe disability), and 3 (3%) were lost to follow-up. Significant prognostic factors for mortality were age older than 35 years, nonreactive pupils, bullet trajectory of bihemispheric (excluding bifrontal), and posterior fossa involvement compared with unihemispheric and bifrontal. Factors that were moderately associated with higher mortality included intracranial pressure (ICP) above 20 mm Hg and Glasgow Coma Scale (GCS) score at presentation of 3 or 4. Upon multivariate analysis, the significant factors for mortality were bullet trajectory and pupillary response. Variables found to be significant for good functional outcome were admission GCS score greater than or equal to 5, pupillary reactivity, and bullet trajectory of unihemispheric or bifrontal. Factors moderately associated with good outcome included age of 35 years or younger, initial ICP 20 mm Hg or lower, and lack of transventricular trajectory. In the multivariate analysis, significant factors for good functional outcome were bullet trajectory and pupillary response, with age moderately associated with improved functional outcomes. The authors also propose a scoring system to estimate survival and functional outcome.

CONCLUSIONS

Age, pupils, GCS score, and bullet trajectory on CT scan can be used to determine likelihood of survival and good functional outcome. The authors advocate assessing patients based on these parameters rather than pronouncing a poor prognosis and withholding aggressive resuscitation based upon low GCS score alone.

Open craniotomy for brain abscess: A forgotten experience?

Background:

Brain abscess carries a high morbidity and mortality despite medical advances. In this paper, we present a single institution's experience with the surgical treatment of brain abscess.

Methods:

We retrospectively analyzed 33 cases of intracranial abscess who underwent surgical treatment between January 2001 and December 2009. Patients were treated with aspiration through a single burr hole, open aspiration with ultrasound guidance, or complete abscess resection. The medical records were analyzed for demographics, clinical presentation, predisposing factors, imaging, microbiological investigations, treatment, and outcomes.

Results:

There were 26 male and 7 female patients, aged between 12 and 78 years. The most common predisposing factor was head trauma. Surgical excision of the abscess was performed in 22 patients, open aspiration in 9 patients, and burr-hole aspiration in 2 patients. Repeat surgical procedure was required in six patients. Mortality in this series was 21%. A favorable outcome (Glasgow outcome scale 4 and 5) was achieved in 54%. There was no significant correlation between outcome and age, predisposing factor, treatment modality, or culture results.

Conclusions:

In this series, most patients were treated with an open technique, either by surgical excision or open aspiration of brain abscess. An open technique may reduce the need for additional imaging, surgical treatment, and length of antibiotic therapy. In resource-limited settings, excision of brain abscess may play a more important role in patient management while maintaining favorable outcomes.

Outcome prediction within twelve hours after severe traumatic brain injury by quantitative cerebral blood flow

We measured quantitative cortical mantle cerebral blood flow (CBF) by stable xenon computed tomography (CT) within the first 12 h after severe traumatic brain injury (TBI) to determine whether neurologic outcome can be predicted by CBF stratification early after injury. Stable xenon CT was used for quantitative measurement of CBF (mL/100 g/min) in 22 cortical mantle regions stratified as follows: low (0-8), intermediate (9-30), normal (31-70), and hyperemic (>70) in 120 patients suffering severe (Glasgow Coma Scale [GCS] score ≤8) TBI. For each of these CBF strata, percentages of total cortical mantle volume were calculated. Outcomes were assessed by Glasgow Outcome Scale (GOS) score at discharge (DC), and 1, 3, and 6 months after discharge. Quantitative cortical mantle CBF differentiated GOS 1 and GOS 2 (dead or vegetative state) from GOS 3-5 (severely disabled to good recovery; p<0.001). Receiver operating characteristic (ROC) curve analysis for percent total normal plus hyperemic flow volume (TNHV) predicting GOS 3-5 outcome at 6 months for CBF measured <6 and <12 h after injury showed ROC area under the curve (AUC) cut-scores of 0.92 and 0.77, respectively. In multivariate analysis, percent TNHV is an independent predictor of GOS 3-5, with an odds ratio of 1.460 per 10 percentage point increase, as is initial GCS score (OR=1.090). The binary version of the Marshall CT score was an independent predictor of 6-month outcome, whereas age was not. These results suggest that quantitative cerebral cortical CBF measured within the first 6 and 12 h after TBI predicts 6-month outcome, which may be useful in guiding patient care and identifying patients for randomized clinical trials. A larger multicenter randomized clinical trial is indicated.

Intraventricular brain abscess

Unlike an intraventricular rupture of a brain abscess, a primary intraventricular abscess is rare. While the former usually presents with acute clinical deterioration and carries a high rate of mortality, the latter tends to present in a subacute fashion. In this paper, we present a 62-year-old female with an intraventricular brain abscess. We discuss the pathogenesis of this clinical entity, describe the management options and review the literature on this topic.

Pulmonary embolus from acute superior sagittal sinus thrombosis secondary to skull fracture: case report

BACKGROUND AND IMPORTANCE

Pulmonary embolus (PE) occurring concurrent with-and as a result of-traumatic superior sagittal sinus thrombosis (SSST) has never before been reported. We report the first case of a patient who presented with acute traumatic SSST and concomitant PE.

CLINICAL PRESENTATION

A 30-year-old man presented with altered mental status after a motorcycle collision, and subsequently developed respiratory distress. Computed tomography (CT) scanning of the head revealed multiple calvarial and skull base fractures, contusions, and hemorrhages. Air was noted within the superior sagittal sinus, indicating a fracture involving the sinus and suggesting thrombus formation. A chest CT scan obtained at the time of presentation revealed a PE in the right pulmonary artery. The patient had no personal or family history of hypercoagulability, and all coagulation study results were within normal limits. Work-up revealed no evidence of long bone fractures or deep venous thrombosis. Initial intervention involved placement of an external ventricular drain, brain tissue oxygen saturation probe, internal jugular venous oxygen saturation monitor, arterial line, and central venous line with extensive treatment of all abnormal values according to established standards. Ultimately, pentobarbital coma was initiated for persistently elevated intracranial pressure (ICP) refractory to conservative measures. Aggressive pulmonary resuscitation was required to maintain adequate oxygenation. Anticoagulation was begun 3 weeks after admission.

CONCLUSION

Our patient had good neurological recovery. This report highlights the possibility of acute PE in the setting of traumatic SSST.

Variants of the endothelial nitric oxide gene and cerebral blood flow after severe traumatic brain injury

Experimental studies suggest that nitric oxide produced by endothelial nitric oxide synthase (NOS3) plays a role in maintaining cerebral blood flow (CBF) after traumatic brain injury (TBI). The purpose of this study was to determine if common variants of the NOS3 gene contribute to hypoperfusion after severe TBI. Fifty-one patients with severe TBI were studied. Cerebral hemodynamics, including global CBF by the stable xenon computed tomography (CT) technique, internal carotid artery flow volume (ICA-FVol), and flow velocity in intracranial vessels, were measured within 12 h of injury, and at 48 h after injury. A blood sample was collected for DNA analysis, and genotyping of the following variants of the NOS3 gene was performed: -786T>C, 894G>T, and 27bp VNTR. Cerebral hemodynamics were most closely related to the-786T>C genotype. CBF averaged 57.7±3.0 mL/100 g/min with the normal T/T genotype, 47.0±2.5 mL/100 g/min with the T/C, and 37.3±8.8 mL/100 g/min with the C/C genotype (p=0.0146). Cerebrovascular resistance followed an inverse pattern with the highest values occurring with the C/C genotype (p=0.0027). The lowest ICA-FVol of 124±43 mL/min was found at 12 h post-injury in the more injured hemisphere of the patients with the C/C genotype (p=0.0085). The mortality rate was 20% in patients with the T/T genotype and 17% with the T/C genotype. In contrast, both of the patients with the C/C genotype were dead at 6 months post-injury (p=0.022). The findings in this study support the importance of NO produced by NOS3 activity in maintaining CBF after TBI, since lower CBF values were found in patients having the -786C allele. The study suggests that a patient's individual genetic makeup may contribute to the brain's response to injury and determine the patient's chances of surviving the injury. The results here will need to be studied in a larger number of patients, but could explain some of the variability in outcome that occurs following severe TBI.

Role of extracellular glutamate measured by cerebral microdialysis in severe traumatic brain injury

OBJECT

Authors of several studies have implied a key role of glutamate, an excitatory amino acid, in the pathophysiology of traumatic brain injury (TBI). However, the place of glutamate measurement in clinical practice and its impact on the management of TBI has yet to be elucidated. The authors' objective in the present study was to evaluate glutamate levels in TBI, analyzing the factors affecting them and determining their prognostic value.

METHODS

A prospective study of patients with severe TBI was conducted with an inclusion criterion of a Glasgow Coma Scale score < or = 8 within 48 hours of injury. Invasive monitoring included intracranial pressure measurements, brain tissue PO(2), jugular venous O(2) saturation, and cerebral microdialysis. Patients received standard care including mass evacuation when indicated and treatment of elevated intracranial pressure values. Demographic data, CT findings, and outcome at 6 months of follow-up were recorded.

RESULTS

One hundred sixty-five patients were included in the study. Initially high glutamate values were predictive of a poor outcome. The mortality rate was 30.3% among patients with glutamate levels > 20 micromol/L, compared with 18% among those with levels < or = 20 micromol/L. Two general patterns were recognized: Pattern 1, glutamate levels tended to normalize over the monitoring period (120 hours); and Pattern 2, glutamate levels tended to increase with time or remain abnormally elevated. Patients showing Pattern 1 had a lower mortality rate (17.1 vs 39.6%) and a better 6-month functional outcome among survivors (41.2 vs 20.7%).

CONCLUSIONS

Glutamate levels measured by microdialysis appear to have an important role in TBI. Data in this study suggest that glutamate levels are correlated with the mortality rate and 6-month functional outcome.

Increased intracranial pressure is associated with elevated cerebrospinal fluid ADH levels in closed-head injury

OBJECTIVES

Head injury frequently results in increased intracranial pressure and brain edema. Investigators have demonstrated that ischemic injury causes an increase in cerebrospinal fluid (CSF) levels of antidiuretic hormone (ADH); increased CSF ADH levels exacerbate cerebral edema, and inhibition of the ADH system with specific ADH antagonists reduces cerebral edema. The current study was designed to test the hypothesis that elevated levels of ADH are present in the CSF of subjects with head injury.

METHODS

Ventricular CSF and blood samples were taken from 11 subjects with head injury and 12 subjects with no known head trauma or injury. ADH levels were analyzed using radioimmunoassay. Severity of increased intracranial pressure (ICP) was rated in head-injured subjects using a four-point ordinal scale, based on which treatments were necessary to reduce ICP.

RESULTS

Subjects with head injury had higher CSF (3.2 versus 1.2 pg/ml; P<0.02) and plasma (4.1 versus 1.4 pg/ml; P<0.02) levels of ADH than did control subjects. In head-injured subjects, CSF ADH levels positively correlated with severity of ICP.

DISCUSSION

The results of this study suggest that ADH plays a role in brain edema associated with closed head injury.

Multiple myeloma presenting as solitary mass in the posterior fossa

Intracranial plasma cell tumors are extremely rare and can either be solitary lesions or part of systemic multiple myeloma. We report a 42-year-old woman who presented with a posterior fossa mass and successfully underwent surgical resection, leading to the diagnosis of multiple myeloma. To our knowledge, this is the first reported case of multiple myeloma presenting as a posterior fossa mass lesion. This report highlights the importance of maintaining plasma cell tumor in the differential of intracranial mass with bony involvement. Furthermore, once the diagnosis is established, further work up is critical to evaluate for systemic disease.

Vacuum-assisted en bloc resection of large convexity meningiomas. Technical note

Convexity meningiomas are common tumors encountered by neurosurgeons. Retracting, grasping, and mobilizing large convexity meningiomas can be difficult and awkward as well as place unwanted forces on surrounding neurovascular structures. The authors present a safe alternative to traditional retraction and manipulation methods by using a modified bulb syringe connected to standard surgical suction to function as a vacuum retractor. This technique allows for rapid, safe, en bloc resection of large convexity meningiomas with little to no pressure on the surrounding brain. The authors present an illustrative case and describe and discuss the technique.

Whipple disease of the central nervous system: an unusual occurrence in association with acquired immune deficiency syndrome

Whipple disease is a multisystem infectious disease caused by Tropheryma whippleii. It commonly affects the CNS and produces neurological symptoms in 10–20% of cases. Central nervous system Whipple disease occurring in patients with AIDS is extremely rare. The authors present a case of a newly diagnosed AIDS patient in whom intracranial Whipple disease was diagnosed by stereotactic brain biopsy.

Outcome in patients with blunt head trauma and a Glasgow Coma Scale score of 3 at presentation

OBJECT

A Glasgow Coma Scale (GCS) score of 3 on presentation in patients with severe traumatic brain injury due to blunt trauma has been recognized as a bad prognostic factor. The reported mortality rate in these patients is very high, even approaching 100% in the presence of fixed and dilated pupils in some series. Consequently, there is often a tendency to treat these patients less aggressively because of the low expectations for a good recovery. In this paper, the authors' purpose is to report their experience in the management of this patient population, analyzing the mortality rate, prognostic factors, and functional outcome of survivors.

METHODS

The authors performed a retrospective review of patients who presented between 1997 and 2007 with blunt head trauma and a GCS score of 3. Demographics, mechanism of injury, examination, blood alcohol level, associated injury, intracranial pressure (ICP), surgical procedures, and outcome were all recorded.

RESULTS

A total of 189 patients met the inclusion criteria and were included in this study. The overall mortality rate was 49.2%. At the 6-month follow-up, 13.2% of the entire series achieved a good functional outcome (Glasgow Outcome Scale [GOS] score of 1 or 2). The patient population was then divided into 2 groups: Group 1 (patients who survived [96]) and Group 2 (patients who died [93]). Patients in Group 1 were younger (mean 33.3 +/- 12.8 vs 40.3 +/- 16.97 years; p = 0.002) and had lower ICP on admission (mean 16.3 +/- 11.1 vs 25.7 +/- 12.7 mm Hg; p < 0.001) than those in Group 2. The difference between the 2 groups regarding sex, mechanism of injury, hypotension on admission, alcohol, surgery, and associated injuries was not statistically significant. The presence of bilateral fixed, dilated pupils was found to be associated with the highest mortality rate (79.7%). Although not statistically significant because of the sample size, pupil status was also a good predictor of the functional outcome at the 6-month follow-up; a good functional outcome (GOS Score 1 or 2) was achieved in 25.5% of patients presenting with bilateral reactive pupils, and 27.6% of patients presenting with a unilateral fixed, dilated pupil, compared with 7.5% for those presenting with bilateral fixed, nondilated pupils, and 1.4% for patients with bilateral fixed, dilated pupils.

CONCLUSIONS

Overall, 50.8% of patients survived their injury and 13.2% achieved a good functional outcome after at 6 months of follow-up (GOS Score 1 or 2). Age, ICP on admission, and pupil status were found to be significant predictive factors of outcome. In particular, pupil size and reactivity appeared to be the most important prognostic factor since the mortality rate was 23.5% in the presence of bilateral reactive pupils and 79.7% in the case of bilateral fixed, dilated pupils. The authors believe that patients having suffered traumatic brain injury and present with a GCS score of 3 should still be treated aggressively initially since a good functional outcome can be obtained in some cases.

Contemporary neurosurgical approaches to neurocysticercosis

Neurocysticercosis (NCC) includes a wide spectrum of illnesses. Newer neurosurgical approaches are being applied to NCC. Although clinical trials are leading to a consensus on medical management, fewer data address neurosurgical approaches. We reviewed all neurocysticercosis patients evaluated by neurosurgery at Ben Taub General Hospital, Houston, Texas, between August 1997 and December 2005. From 31 patients that had a neurosurgical evaluation, 16 patients were treated with shunts (5 had shunt failure requiring revision), 13 by surgical resection of cysts (9 underwent craniotomy and 4 endoscopy), and 2 by medical therapy. A fifth endoscopy was performed in one patient with shunt failure. None of the endoscopic patients needed another intervention. Despite the availability of anti-parasitic and anti-inflammatory therapies, neurosurgery continues to play an important role in the management of selected cases of NCC. In contrast to the high rate of shunt failure, neuroendoscopy seems to be associated with higher success rate than any other neurosurgical approach.

Brain tissue oxygen tension response to induced hyperoxia reduced in hypoperfused brain

Object

Increasing PaO2 can increase brain tissue PO2 (PbtO2). Nevertheless, the small increase in arterial O2 content induced by hyperoxia does not increase O2 delivery much, especially when cerebral blood flow (CBF) is low, and the effectiveness of hyperoxia as a therapeutic intervention remains controversial. The purpose of this study was to examine the role of regional (r)CBF at the site of the PO2 probe in determining the response of PbtO2 to induced hyperoxia.

Methods

The authors measured PaO2 and PbtO2 at baseline normoxic conditions and after increasing inspired O2 concentration to 100% on 111 occasions in 83 patients with severe traumatic brain injury in whom a stable xenon–enhanced computed tomography measurement of CBF was available. The O2 reactivity was calculated as the change in PbtO2 × 100/change in PaO2.

Results

The O2 reactivity was significantly different (p < 0.001) at the 5 levels of rCBF (<10, 11–15, 16–20, 21–40, and > 40 ml/100 g/min). When rCBF was < 20 ml/100 g/min, the increase in PbtO2 induced by hyperoxia was very small compared with the increase that occurred when rCBF was > 20 ml/100 g/min.

Conclusions

Although the level of CBF is probably only one of the factors that determines the PbtO2 response to hyperoxia, it is apparent from these results that the areas of the brain that would most likely benefit from improved oxygenation are the areas that are the least likely to have increased PbtO2.

Adult respiratory distress syndrome: a complication of induced hypertension after severe head injury

OBJECT

The factors involved in the development of adult respiratory distress syndrome (ARDS) after severe head injury were studied. The presence of ARDS complicates the treatment of patients with severe head injury, both because hypoxia causes additional injury to the brain and because therapies that are used to protect the lungs and improve oxygenation in patients with ARDS can reduce cerebral blood flow (CBF) and increase intracranial pressure (ICP). In a recent randomized trial of two head-injury management strategies (ICP-targeted and CBF-targeted), a fivefold increase in the incidence of ARDS was observed in the CBF-targeted group.

METHODS

Injury severity, physiological data, and treatment data in 18 patients in whom ARDS had developed were compared with the remaining 171 patients in the randomized trial in whom it had not developed. Logistic regression analysis was used to study the interaction of the factors that were related to the development of ARDS. In the final exact logistic regression model, several factors were found to be significantly associated with an increased risk of ARDS: administration of epinephrine (5.7-fold increased risk), administration of dopamine in a larger than median dose (10.8-fold increased risk), and a history of drug abuse (3.1-fold increased risk).

CONCLUSIONS

Although this clinical trial was not designed to study the association of management strategy and the occurrence of ARDS, the data strongly indicated that induced hypertension in this high-risk group of patients is associated with the development of symptomatic ARDS.

Extracellular glutamate and aspartate in head injured patients

Eighty-six patients in coma from a severe head injury underwent monitoring of extracellular concentrations of glutamate and aspartate by a microdialysis technique during the first few days after injury. The median value for glutamate was 7.4 microM (interquartile range 3.6-18.8 microM). The median value for aspartate was 2.4 microM (interquartile range 1.1-5.0 microM). Average values for the dialysate concentrations of glutamate and aspartate, were closely related to outcome (p < .001 and p = .002, respectively). Patients who died of their head injury had significantly higher dialysate glutamate and aspartate concentrations compared to patients who recovered to a Glasgow Outcome Score of good recovery or moderate disability. Dialysate glutamate and aspartate levels were also significantly related to type of injury (p = .008 and p = .004, respectively). The highest values were found in patients with gunshot wounds, followed by patients with evacuated and unevacuated mass lesions. Patients with diffuse injuries had the lowest values of glutamate and aspartate. These results suggest that excitatory amino acids may play a role in the evolution of injury to the brain after trauma.

Interstitial brain adenosine and xanthine increase during jugular venous oxygen desaturations in humans after traumatic brain injury

OBJECTIVE

Adenosine decreases the cerebral metabolic rate for oxygen and increases cerebral blood flow, and it may play an important role in cerebrometabolic and cerebrovascular responses to hypoperfusion after traumatic brain injury. Jugular venous oxygen saturation is monitored after traumatic brain injury to assess brain oxygen extraction, and desaturations may reflect secondary brain insults. We hypothesized that brain interstitial adenosine and related purine metabolites would be increased during jugular venous oxygen saturation desaturations (<50%) and determined associations between the purines, lactate, and glucose to assess the role of adenosine during secondary insults in humans.

DESIGN

Study of critically ill adults with severe traumatic brain injury.

SETTING

Adult neurointensive care unit.

PATIENTS

We prospectively defined periods of normal saturation and desaturation in six patients after severe traumatic brain injury.

INTERVENTIONS

During these periods, cerebral microdialysis samples of brain interstitial fluid were collected, and adenosine and purine metabolites were measured by high-pressure liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

Adenosine increased 3.1-fold and xanthine increased 2.5-fold during desaturation periods (both p <.05 vs. normal saturation period, signed rank). Adenosine, xanthine, hypoxanthine, and cyclic-adenosine monophosphate correlated with lactate over both study periods (r(2) =.32,.14,.31,.07, and.26, respectively, all p <.05, Pearson product moment correlation).

CONCLUSION

The marked increases in interstitial brain adenosine that occur during jugular venous oxygen desaturations suggest that adenosine may play an important role during periods of secondary insults after traumatic brain injury. The correlation of these metabolites with lactate further suggests that adenosine is increased during periods of enhanced glycolytic metabolism.

Midline shift after severe head injury: pathophysiologic implications

OBJECTIVE

To investigate the mechanism of the adverse effect of midline shift after severe traumatic brain injury.

METHODS

This study compared averaged cerebral metabolic parameters of patients with midline shift > 5 mm (S) on initial computerized tomography scan to those of patients with shift < or = 5 mm (NS). The effect of an acute subdural hematoma (SDH) was determined by separating patients into those with and those without SDH and then re-examining the effect of shift in these subgroups.

RESULTS

Four hundred fifty-four patients were studied. Cerebral metabolic rate of oxygen (CMRO2, in mL/100 g per min) was always lower with shift: 1.74 for SDH-S versus 2.21 for SDH-NS (p < 0.001), and 1.80 for non-SDH-S versus 2.24 for non-SDH-NS (p < 0.001). No other major effects of shift were seen in SDH patients. Among non-SDH patients, shift was associated with higher intracranial pressure (ICP): 23.1 mm Hg versus 16.3 mm Hg (p < 0.001). Other differences between shift and nonshift patients in the non-SDH group were due at least in part to interventions to treat the elevated ICP.

CONCLUSION

Midline shift after severe traumatic brain injury is associated with reduced CMRo2, regardless of whether or not SDH is present. The deleterious effects of subdural blood may be related more to the mass effect of large SDHs than to the biochemical abnormalities caused by small amounts of blood in the subdural space.

Simultaneous measurement of cortical potassium, calcium, and magnesium levels measured in head injured patients using microdialysis with ion chromatography

Potassium, calcium and magnesium were measured in 3717 microdialysate samples in 43 patients with head injury experiencing refractory increased ICP, episodes of jugular venous oxygen desaturation and brain death. Cation analysis was performed with 'ion chromatography'. Potassium levels remained stable until severe physiological deterioration occurred, whereupon they increased 100-400%, usually associated with release of amino-acids including glutamate, aspartate, and taurine into the extracellular space. The magnesium and calcium levels remained unchanged, regardless of the severity of physiological deterioration.

Similarities between civilian gunshot wounds to the head and nongunshot head injuries

BACKGROUND

This investigation compared the cerebral pathophysiologic status of gunshot wounds to the head (GSWH) with that of severe head injury of other causes (non-GSWH).

METHODS

Data were collected prospectively from 71 GSWH and 541 non-GSWH patients. The two groups had similar demographic characteristics and injury severities. Cerebral metabolic parameters for each patient were averaged for the entire period of monitoring. These per-patient averages were compared between GSWH and non-GSWH groups.

RESULTS

Median intracranial pressure was 21.4 mm Hg in GSWH patients vs. 16.7 mm Hg in non-GSWH patients (p < 0.001). Mean arterial pressures were similar, but the higher intracranial pressure in GSWH patients produced a lower median cerebral perfusion pressure. Cerebral blood flow, cerebrovascular resistance, cerebral metabolic rate of oxygen, average jugular venous oxygen saturation, and number of jugular venous desaturations did not differ significantly between the groups. Three-month outcome was death in 43% of GSWH patients and 32% of non-GSWH patients, persistent vegetative state or severe disability in 33% and 32%, respectively, and moderate disability or good recovery in 24% and 36%, respectively. These outcomes were not significantly different (p = 0.11).

CONCLUSION

GSWH patients suffer global cerebral metabolic disturbances that are at least as severe as those seen in non-GSWH patients with injuries of comparable severity. This selected population of GSWH patients may enjoy outcomes comparable to those of non-GSWH patients if they are treated by the same aggressive protocols.

Comparison of jugular venous oxygen saturation and brain tissue Po2 as monitors of cerebral ischemia after head injury

OBJECTIVE

To compare the characteristics of jugular venous oxygen saturation (Sjvo2) and brain tissue Po2 (Pbto2) as monitors for cerebral ischemia after severe head injury. Sjvo2 has been useful as a monitor for cerebral ischemia, but it is limited by its inability to identify regional cerebral ischemia. Pbto2 may be superior to Sjvo2 for this purpose, because oxygenation in localized areas of the brain can be monitored.

DESIGN

Sjvo2 and Pbto2 were successfully monitored in 58 patients with severe head injury. The changes in Sjvo2 and Pbto2 were compared during ischemic episodes.

SETTING

Neurosurgical intensive care unit of a level I trauma center.

MEASUREMENTS AND MAIN RESULTS

During the monitoring period, which averaged 90 hrs/patient, there were 54 episodes during which Sjvo2 decreased to <50% and/or Pbto2 decreased to <8 torr. Two of these episodes were caused by an infarction in the area of the Po2 probe, leaving 52 episodes of global hypoxia/ischemia that were identified by one of the two monitors. The sensitivities of the two monitors for detecting ischemia, using the thresholds of 50% and 8 torr for Sjvo2 and Pbto2, respectively, were similar. The Sjvo2 catheter detected 69.7% of the episodes and the Pbto2 catheter detected 63.5% of the episodes. In most of the remaining episodes, both probes reflected a decrease in oxygenation, but not to levels below the defined thresholds. The major differences in the two measures of oxygenation included the following: a) Sjvo2 more consistently reflected a reduction in oxygenation during hyperventilation; b) Pbto2 was affected more by changes in arterial Po2; and c) during severe global ischemia, Pbto2 decreased to 0 and remained at 0, whereas Sjvo2 initially decreased but then increased again as cerebral blood flow ceased, and the only blood in the jugular bulb was of extracerebral origin.

CONCLUSIONS

The two monitors provide complimentary information, and neither monitor alone identifies all episodes of ischemia. The best strategy for using these monitors is to take advantage of the unique features of each monitor. Sjvo2 should be used as a monitor of global oxygenation; but Pbto2 should be used as a monitor of local oxygenation, ideally with the catheter placed in an area of the brain that is vulnerable to ischemia but that may be salvageable with appropriate treatment.

Prevention of secondary ischemic insults after severe head injury

OBJECTIVE

The purpose of this study was to compare the effects of two acute-care management strategies on the frequency of jugular venous desaturation and refractory intracranial hypertension and on long-term neurologic outcome in patients with severe head injury.

DESIGN

Randomized clinical trial.

SETTING

Level I trauma hospital.

PATIENTS

One hundred eighty-nine adults admitted in coma because of severe head injury.

INTERVENTIONS

Patients were assigned to either cerebral blood flow (CBF)-targeted or intracranial pressure (ICP)-targeted management protocols during randomly assigned time blocks. In the CBF-targeted protocol, cerebral perfusion pressure was kept at >70 mm Hg and PaCO2 was kept at approximately 35 torr (4.67 kPa). In the ICP-targeted protocol, cerebral perfusion pressure was kept at >50 mm Hg and hyperventilation to a PaCO2 of 25-30 torr (3.33-4.00 kPa) was used to treat intracranial hypertension.

MEASUREMENTS AND MAIN RESULTS

The CBF-targeted protocol reduced the frequency of jugular desaturation from 50.6% to 30% (p = .006). Even when the frequency of jugular desaturation was adjusted for all confounding factors that were significant, the risk of cerebral ischemia was 2.4-fold greater with the ICP-targeted protocol. Despite the reduction in secondary ischemic insults, there was no difference in neurologic outcome. Failure to alter long-term neurologic outcome was probably attributable to two major factors. A low jugular venous oxygen saturation was treated in both groups, minimizing the injury that occurred in the ICP-targeted group. The beneficial effects of the CBF-targeted protocol may have been offset by a five-fold increase in the frequency of adult respiratory distress syndrome.

CONCLUSIONS

Secondary ischemic insults caused by systemic factors after severe head injury can be prevented with a targeted management protocol. However, potential adverse effects of this management strategy may offset these beneficial effects.

Cerebral hemodynamic effects of pentobarbital coma in head-injured patients

The purpose of this study was to examine the changes in cerebral hemodynamics of head-injured patients undergoing barbiturate treatment of refractory intracranial hypertension. Cerebral blood flow (CBF) and metabolism variables were measured in 67 severely head-injured patients at the following times: before the loading dose of pentobarbital; after the loading dose of pentobarbital (average pentobarbital level 28.1+/-8.3 microg/mL); and 3 days later, when the peak pentobarbital level averaged 42.5+/-17.2 microg/mL. Intracranial pressure (ICP) and mean arterial blood pressure (MAP) were decreased by the loading dose of pentobarbital by an average of 12 and 9 mm Hg, respectively. Cerebral perfusion pressure (CPP) was unchanged when the entire group was analyzed together. CBF, cerebral oxygen consumption (CMR(O)2), and arteriovenous oxygen difference (AVD(O)2) were significantly decreased after the loading dose of pentobarbital, by 20%, 31%, and 11%, respectively. The average cerebrovascular resistance (CVR) was increased by 20%. The change in CMR(O)2 with the loading dose of pentobarbital was closely related to the pretreatment value (n = 67, r2 = 0.65, p < .001). Thirty (45%) of the patients had a "good ICP response," with a reduction in ICP from 34+/-9 to 15+/-5 mm Hg after the initial loading dose of pentobarbital. Twenty-seven (40%) of the patients had a "partial ICP response," with ICP decreasing but still remaining above 20 mm Hg after the loading dose of pentobarbital. In the remaining 10 patients, ICP did not change or even increased after pentobarbital. In the 30 patients with a good ICP response, pretreatment CMR(O)2 and AVD(O)2 were greater before administration of pentobarbital, and CMR(O)2 and AVD(O)2 decreased more with the loading dose of pentobarbital, than in the patients with partial or no ICP response. The outcome was significantly better in the patients with a good or partial ICP response to pentobarbital, with 21% of these patients having a good recovery or moderate disability at 3 months after injury, compared with 100% persistent vegetative state or death in the nonresponders. In summary, barbiturate coma can be a useful treatment modality for acutely reducing ICP in selected patients. Patients with overwhelmingly severe injuries are not likely to benefit, partly because their CMR(O)2 is already markedly reduced by the injury and partly because their outcome is already predetermined by the injury. Patients with systemic hypotension are not likely to have a good response because hypotension limits the amount of barbiturates that can be given.

Extracellular lactate and glucose alterations in the brain after head injury measured by microdialysis

OBJECTIVE

To study cerebral glucose and lactate metabolism in head-injured patients using microdialysis.

DESIGN

Prospective, nonrandomized, clinical study.

SETTING

Neurosurgical intensive care unit in a university-affiliated county hospital.

PATIENTS

One hundred twenty-six head-injured patients.

INTERVENTIONS

Cerebral cortical neurochemical monitoring using microdialysis coupled with systemic hemodynamic and oxygenation monitoring, measurement of cerebral perfusion pressure and intracranial pressure, and measurement of global cerebral oxygenation using jugular venous oxygen saturation in all 126 patients. In selected cases, cerebral blood flow was also measured using cortical thermodilution probes in 33 patients, and regional cerebral oxygenation was measured using PO2 probes in 65 patients.

MEASUREMENTS AND MAIN RESULTS

Elevated extracellular lactate, reduced glucose, and an elevated lactate/glucose ratio were observed with cerebral hypoxia and ischemia. Elevated lactate and an increased lactate/glucose ratio strongly correlated with death. Other more subtle alterations of lactate and glucose were seen early after injury that may reflect compensatory alterations in cerebral metabolism.

CONCLUSIONS

Clinical neurochemical monitoring of glucose and lactate levels in the extracellular space of the cerebral cortex is technically feasible and provides insight into the bioenergetic status of the brain. Increased lactate and decreased glucose, indicating accelerated glycolysis, commonly occurred with cerebral ischemia or hypoxia, and increased anaerobic glycolysis in this setting is associated with a poor outcome.

Relationship of brain tissue PO2 to outcome after severe head injury

OBJECTIVE

To determine thresholds of brain tissue PO2 (PbtO2) that are critical for survival after severe head injury.

DESIGN

Prospective data collection.

SETTING

Neurosurgical intensive care unit of Ben Taub General Hospital, a comprehensive academic neurosurgical facility and Level I trauma center.

PATIENTS

Forty-three severely head-injured patients who were not obeying commands on presentation or whose condition deteriorated to this level shortly after admission.

INTERVENTIONS

Intracerebral placement of Licox (n=39) or Paratrend (n=4) PO2 probes during craniotomy or in the intensive care unit.

MEASUREMENTS AND MAIN RESULTS

PbtO2 monitoring continued for an average of 84.6+/-41.8 hrs. The probes were calibrated before insertion according to the manufacturer's specifications. After removal, probes were tested in room air and in blood gas standard calibration solutions. PbtO2 data were analyzed by comparing the average time that PbtO2 was below the values of 20, 15, 10, 8, 6, 4, and 2 torr (2.7, 2.0, 1.3, 1.0, 0.8, 0.5, and 0.3 kPa, respectively) in patients who were living 3 mos after injury vs. those who died. A Tobit regression analysis using maximum likelihood methods was utilized. Both Licox and Paratrend probes functioned well in room air and in the Level I control. However, in the zero-oxygen solution, the Paratrend probes gave an average reading of 7.0+/-1.4 torr (0.9+/-0.2 kPa), compared with 0.3+/-0.3 torr (0.04+/-0.04 kPa) for the Licox probes.

CONCLUSIONS

Analysis of the PbtO2 monitoring data suggested that the likelihood of death increased with increasing duration of time at or below a PbtO2 of 15 torr (2.0 kPa) or with the occurrence of any PbtO2 values of < or =6 torr (< or =0.8 kPa).

Comparison of brain tissue oxygen tension to microdialysis-based measures of cerebral ischemia in fatally head-injured humans

This study investigated the relationship between brain tissue oxygen tension (PbtO2) and cerebral microdialysate concentrations of several compounds in five patients with refractory intracranial hypertension after severe head injury. The following substances were assayed: lactate and glucose; the excitatory amino acids glutamate and aspartate; and the cations potassium, calcium, and magnesium. Glucose concentrations did not correlate with PbtO2, but lactate increased as PbtO2 decreased. The lactate/glucose ratio exhibited a close relationship to PbtO2, increasing sharply only when oxygen tension reached zero. Although glucose and oxygen eventually reached very low levels and zero, respectively, in these fatally head-injured patients, the terminal decrease in PbtO2 slightly preceded that of glucose in four of the five patients. This time lag is the cause of the poor correlation between glucose and PbtO2. Glutamate and aspartate concentrations both demonstrated a close relationship to PbtO2, with sharp increases not occurring until PbtO2 was zero. Concentrations of these amino acids exhibited a similar pattern in response to decreasing glucose concentrations. Potassium concentrations began increasing at a PbtO2 of 35 mm Hg, which is not generally considered indicative of hypoxia. Sharper increases began occurring once PbtO2 dropped below 15 mm Hg, with a slight rise in the minimum potassium concentrations recorded at these low PbtO2 values. Calcium and magnesium concentrations did not vary in response to PbtO2. In summary, the most robust biochemical indicators of cerebral anoxia were elevations in the lactate/glucose ratio and in the concentrations of lactate and of the excitatory amino acids glutamate and aspartate. Furthermore, the fact that glucose concentrations continue to decrease for a short period after oxygen levels reach zero suggests that cells continue to utilize glucose anaerobically for such functions as maintenance of cellular integrity, with collapse of the cell membrane as evidenced by increases of extracellular glutamate and aspartate not occurring until both oxygen and glucose concentrations reach zero.

Metabolic changes in the brain during transient ischemia measured with microdialysis

Forty-four patients with severe head injury were monitored for episodes of cerebral ischemia using jugular venous oxygen saturation (sjvO2), brain tissue pO2 (ti-pO2), and a microdialysis probe. The concentration of lactate and glucose were measured in the microdialysate. A total of 10 episodes of global ischemia were observed. The characteristic pattern of a simultaneous decrease in sjvO2 and brain ti-pO2 with an increase in the concentration of lactate occurred in all 10 patients. In addition, 3 episodes of regional ischemia were observed. Although brain ti-pO2 decreased to very low values and the concentration of lactate increased in the microdialysate, sjvO2 remained unchanged. Brain ti-pO2 adds another dimension to our cerebral monitoring by allowing the detection of regional cerebral ischemia.

Brain temperature exceeds systemic temperature in head-injured patients

OBJECTIVE

To identify the temperature differences in readings taken from the brain, jugular bulb, and core body in head-injured patients.

DESIGN

Prospective, observational study.

SETTING

Neurosurgical intensive care unit of a university-affiliated county hospital.

PATIENTS

Thirty patients with severe head injuries had measurements of brain and core body temperatures. Fourteen patients also had measurements of jugular venous blood at the level of the jugular bulb.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Brain temperature was increased an average of 2.0 degrees F (1.1 degrees C) over the core body temperature. In individual patients, the average brain temperature increase over the core body temperature ranged from -0.5 degrees to 3.8 degrees F (-0.30 degrees to 2.1 degrees C). Jugular vein and core body temperatures were similar. The difference in the brain and body temperatures increased when cerebral perfusion pressure decreased to between 20 and 50 mm Hg. The difference in the brain and body temperatures decreased in those patients treated with barbiturate coma.

CONCLUSIONS

Direct measurement of temperature in head-injured patients is a safe procedure. Temperatures in the brain are typically increased over the core body temperature and the jugular bulb temperatures. Jugular vein temperature measurement is not a good measurement of brain temperature since it reflects body, not brain temperature. These findings support the potential importance of monitoring brain temperature and the importance of controlling fever in severely head-injured patients since brain temperature may be higher than expected.