Kent Gøran Moen

A longitudinal MRI study of traumatic axonal injury in patients with moderate and severe traumatic brain injury

Objective To study the evolution of traumatic axonal injury (TAI) detected by structural MRI in patients with moderate and severe traumatic brain injury (TBI) during the first year and relate findings to outcome. Methods 58 patients with TBI (Glasgow Coma Scale score 3–13) were examined with MRI at a median of 7 days, 3 months and 12 months post injury. TAI lesions were evaluated blinded and categorised into three stages based on location: hemispheres, corpus callosum and brainstem. Lesions in T2* weighted gradient echo (GRE), fluid attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI) were counted and FLAIR lesion volumes were estimated. Inter-rater reliability score was calculated. Outcome was assessed 12 months post injury using the Glasgow Outcome Scale Extended. Results In the initial MRI, 31% had brainstem lesions compared with 17% at 3 months (p=0.008). In the FLAIR sequences, number and volumes of lesions were reduced from early to 3 months (p<0.001). In T2*GRE sequences, the number of lesions persisted at 3 months but was reduced at 12 months (p=0.007). The number of lesions in DWI and volume of FLAIR lesions on early MRI predicted worse clinical outcome in adjusted analyses (p<0.05). Conclusion This is the first study to demonstrate and quantify attenuation of non-haemorrhagic TAI lesions on structural MRI during the first 3 months after TBI; most importantly, the disappearance of brainstem lesions. Haemorrhagic TAI lesions attenuate first after 3 months. Only early MRI findings predicted clinical outcome after adjustment for other prognostic factors. Hence valuable clinical information may be missed if MRI is performed too late after TBI.

Prospective longitudinal MRI study of brain volumes and diffusion changes during the first year after moderate to severe traumatic brain injury

The objectives of this prospective study in 62 moderate–severe TBI patients were to investigate volume change in cortical gray matter (GM), hippocampus, lenticular nucleus, lobar white matter (WM), brainstem and ventricles using a within subject design and repeated MRI in the early phase (1–26 days) and 3 and 12 months postinjury and to assess changes in GM apparent diffusion coefficient (ADC) in normal appearing tissue in the cortex, hippocampus and brainstem. The impact of Glasgow Coma Scale (GCS) score at admission, duration of post-traumatic amnesia (PTA), and diffusion axonal injury (DAI) grade on brain volumes and ADC values over time was assessed. Lastly, we determined if MRI-derived brain volumes from the 3-month scans provided additional, significant predictive value to 12-month outcome classified with the Glasgow Outcome Scale—Extended after adjusting for GCS, PTA and age. Cortical GM loss was rapid, largely finished by 3 months, but the volume reduction was unrelated to GCS score, PTA, or presence of DAI. However, cortical GM volume at 3 months was a significant independent predictor of 12-month outcome. Volume loss in the hippocampus and lenticular nucleus was protracted and statistically significant first at 12 months. Slopes of volume reduction over time for the cortical and subcortical GGM were significantly different. Hippocampal volume loss was most pronounced and rapid in individuals with PTA > 2 weeks. The 3-month volumes of the hippocampus and lentiform nucleus were the best independent predictors of 12-month outcome after adjusting for GCS, PTA and age. In the brainstem, volume loss was significant at both 3 and 12 months. Brainstem volume reduction was associated with lower GCS score and the presence of DAI. Lobar WM volume was significantly decreased first after 12 months. Surprisingly DAI grade had no impact on lobar WM volume. Ventricular dilation developed predominantly during the first 3 months, and was strongly associated with volume changes in the brainstem and cortical GM, but not lobar WM volume. Higher ADC values were detected in the cortex in individuals with severe TBI, DAI and PTA > 2 weeks, from 3 months. There were no associations between ADC values and brain volumes, and ADC values did not predict outcome.

Intensive care and traumatic brain injury after the introduction of a treatment protocol: a prospective study

Traumatic brain injury (TBI) treatment protocols have been introduced in the intensive care unit (ICU) to avoid secondary brain injury. In this study, we aimed to evaluate the deviations from such a treatment protocol and the frequency of extracranial complications, and relate these findings to outcome.

White matter microstructure in chronic moderate-to-severe traumatic brain injury: Impact of acute-phase injury-related variables and associations with outcome measures

This study examines how injury mechanisms and early neuroimaging and clinical measures impact white matter (WM) fractional anisotropy (FA), mean diffusivity (MD), and tract volumes in the chronic phase of traumatic brain injury (TBI) and how WM integrity in the chronic phase is associated with different outcome measures obtained at the same time. Diffusion tensor imaging (DTI) at 3 T was acquired more than 1 year after TBI in 49 moderate‐to‐severe‐TBI survivors and 50 matched controls. DTI data were analyzed with tract‐based spatial statistics and automated tractography. Moderate‐to‐severe TBI led to widespread FA decreases, MD increases, and tract volume reductions. In severe TBI and in acceleration/deceleration injuries, a specific FA loss was detected. A particular loss of FA was also present in the thalamus and the brainstem in all grades of diffuse axonal injury. Acute‐phase Glasgow Coma Scale scores, number of microhemorrhages on T2*, lesion volume on fluid‐attenuated inversion recovery, and duration of posttraumatic amnesia were associated with more widespread FA loss and MD increases in chronic TBI. Episodes of cerebral perfusion pressure <70 mmHg were specifically associated with reduced MD. Neither episodes of intracranial pressure >20 mmHg nor acute‐phase Rotterdam CT scores were associated with WM changes. Glasgow Outcome Scale Extended scores and performance‐based cognitive control functioning were associated with FA and MD changes, but self‐reported cognitive control functioning was not. In conclusion, FA loss specifically reflects the primary injury severity and mechanism, whereas FA and MD changes are associated with objective measures of general and cognitive control functioning.

Moderate and severe traumatic brain injury: effect of blood alcohol concentration on Glasgow Coma Scale score and relation to computed tomography findings

OBJECT The influence of alcohol is assumed to reduce consciousness in patients with traumatic brain injury (TBI), but research findings are divergent. The aim of this investigation was to study the effects of different levels of blood alcohol concentration (BAC) on the Glasgow Coma Scale (GCS) scores in patients with moderate and severe TBI and to relate the findings to brain injury severity based on the admission CT scan. METHODS In this cohort study, 265 patients (age range 16-70 years) who were admitted to St. Olavs University Hospital with moderate and severe TBI during a 7-year period were prospectively registered. Of these, 217 patients (82%) had measured BAC. Effects of 4 BAC groups on GCS score were examined with ordinal logistic regression analyses, and the GCS scores were inverted to give an OR > 1. The Rotterdam CT score based on admission CT scan was used to adjust for brain injury severity (best score 1 and worst score 6) by stratifying patients into 2 brain injury severity groups (Rotterdam CT scores of 1-3 and 4-6). RESULTS Of all patients with measured BAC, 91% had intracranial CT findings and 43% had BAC > 0 mg/dl. The median GCS score was lower in the alcohol-positive patients (6.5, interquartile range [IQR] 4-10) than in the alcohol-negative patients (9, IQR 6-13; p < 0.01). No significant differences were found between alcohol-positive and alcohol-negative patients regarding other injury severity variables. Increasing BAC was a significant predictor of lower GCS score in a dose-dependent manner in age-adjusted analyses, with OR 2.7 (range 1.4-5.0) and 3.2 (range 1.5-6.9) for the 2 highest BAC groups (p < 0.01). Subgroup analyses showed an increasing effect of BAC group on GCS scores in patients with Rotterdam CT scores of 1-3: OR 3.1 (range 1.4-6.6) and 6.7 (range 2.7-16.7) for the 2 highest BAC groups (p < 0.01). No such relationship was found in patients with Rotterdam CT scores of 4-6 (p = 0.14-0.75). CONCLUSIONS Influence of alcohol significantly reduced the GCS score in a dose-dependent manner in patients with moderate and severe TBI and with Rotterdam CT scores of 1-3. In patients with Rotterdam CT scores of 4-6, and therefore more CT findings indicating increased intracranial pressure, the brain injury itself seemed to overrun the depressing effect of the alcohol on the CNS. This finding is in agreement with the assumption of many clinicians in the emergency situation.

Direct transport versus interhospital transfer of patients with severe head injury in Norway.

Objective This study compares injury severity and outcome of patients with severe head injury admitted directly to a neurosurgical department with those initially transferred to a local hospital. Methods A retrospective analysis of all patients with severe head injury admitted to the Department of Neurosurgery at St Olav University Hospital, Norway, was carried out from 1998 throughout 2002. Results The study included 146 patients with a median age of 34 (1–88) years. Patients transported directly (57%) had lower field Glasgow Coma Scale (fGCS) [5.5 (3–15) vs. 7 (3–15), P=0.002], higher Injury Severity Score [31.8 (9–75) vs. 27.0 (9–75), P=0.023], higher mortality rates (31 vs. 15%, P=0.042) and reached the neurosurgical department earlier [1.8 (0.3–15.8) vs. 5.5h (0.8–23.0), P<0.001] than those undergoing transfer to a local hospital. Significantly more patients in the direct admission group with a fGCS ≤8 (83%) were intubated at the scene of accident than in the transfer group (38%) (P<0.001). Multiple regression analysis adjusting for age, GCS and pupillary abnormalities did not predict increased mortality for the transfer group [odds ratio 0.43 (0.16, 1.14), P=0.09]. Conclusion Patients with a severe head injury admitted directly to the neurosurgical department are more severely injured, more frequently get advanced medical treatment in the field, and are undergoing surgery earlier than transferred patients.

A Longitudinal Magnetic Resonance Imaging Study of the Apparent Diffusion Coefficient Values in Corpus Callosum during the First Year after Traumatic Brain Injury

The objective of this study was to explore the evolution of apparent diffusion coefficient (ADC) values in magnetic resonance imaging (MRI) in normal-appearing tissue of the corpus callosum during the 1st year after traumatic brain injury (TBI), and relate findings to outcome. Fifty-seven patients (mean age 34 [range 11-63] years) with moderate to severe TBI were examined with diffusion weighted MRI at three time points (median 7 days, 3 and 12 months), and a sex- and age-matched control group of 47 healthy individuals, were examined once. The corpus callosum was subdivided and the mean ADC values computed blinded in 10 regions of interests without any visible lesions in the ADC map. Outcome measures were Glasgow Outcome Scale Extended (GOSE) and neuropsychological domain scores at 12 months. We found a gradual increase of the mean ADC values during the 12 month follow-up, most evident in the posterior truncus (r=0.19, p<0.001). Compared with the healthy control group, we found higher mean ADC values in posterior truncus both at 3 months (p=0.021) and 12 months (p=0.003) post-injury. Patients with fluid-attenuated inversion recovery (FLAIR) lesions in the corpus callosum in the early MRI, and patients with disability (GOSE score ≤6) showed evidence of increased mean ADC values in the genu and posterior truncus at 12 months. Mean ADC values in posterior parts of the corpus callosum at 3 months predicted the sensory-motor function domain score (p=0.010-0.028). During the 1st year after moderate and severe TBI, we demonstrated a slowly evolving disruption of the microstructure in normal appearing corpus callosum in the ADC map, most evident in the posterior truncus. The mean ADC values were associated with both outcome and ability to perform speeded, complex sensory-motor action.

Traumatic axonal injury: Relationships between lesions in the early phase and diffusion tensor imaging parameters in the chronic phase of traumatic brain injury

This prospective study of traumatic brain injury (TBI) patients investigates fractional anisotropy (FA) from chronic diffusion tensor imaging (DTI) in areas corresponding to persistent and transient traumatic axonal injury (TAI) lesions detected in clinical MRI from the early phase. Thirty‐eight patients (mean 24.7 [range 13–63] years of age) with moderate‐to‐severe TBI and 42 age‐ and sex‐matched healthy controls were included. Patients underwent 1.5‐T clinical MRI in the early phase (median 7 days), including fluid‐attenuated inversion recovery (FLAIR) and T2* gradient echo (T2*GRE) sequences. TAI lesions from the early phase were characterized as nonhemorrhagic or microhemorrhagic. In the chronic phase (median 3 years), patients and controls were imaged at 3 T with FLAIR, T2*GRE, T1, and DTI sequences. TAI lesions were classified as transient or persistent. The FLAIR/T2*GRE images from the early phase were linearly registered to the FA images from the chronic phase and lesions manually segmented on the FA‐registered FLAIR/T2*GRE images. For regions of interest (ROIs) from both nonhemorrhagic and microhemorrhagic lesion, we found a significant linear trend of lower mean FA from ROIs in healthy controls to ROIs in patients without either nonhemorrhagic or microhemorrhagic lesions and further to transient and finally persistent lesion ROIs (P < 0.001). Histogram analyses showed lower FA in persistent compared with transient nonhemorrhagic lesion ROIs (P < 0.001), but this was not found in microhemorrhagic lesion ROIs (P = 0.08–0.55). The demonstrated linear trend of lower FA values from healthy controls to persistent lesion ROIs was found in both nonhemorrhagic and microhemorrhagic lesions and indicates a gradual increasing disruption of the microstructure. Lower FA values in persistent compared with transient lesions were found only in nonhemorrhagic lesions. Thus, clinical MRI techniques are able to depict important aspects of white matter pathology across the stages of TBI.

No growth on serial MRI scans of a low grade glioma?

Dear Editor, Early resection is now considered the optimal surgical strategy for low-grade glioma (LGG) [2]. However, some are still reluctant because of potential iatrogenic injury during removal of tumors that allegedly may remain stable for years. However, we and others question the notion of stable disease in LGG [3]. We, therefore, would like to briefly present a typical patient with so-called stable disease. A 29-year-old female patient had an MRI scan that led to the incidental discovery of a subcortical hyperintense lesion on FLAIR (fluid attenuated inversion recovery) images. The lesion was located within the left insula and was followedwith a wait-and-scan approach. Repeated MRI scans were performed after 12 and 22 months, and a stable lesion with “no sign of growth” was described. A scan performed 32 months after the index scan described possible growth of the lesion and the patient was thereafter referred for surgery. We re-assessed the “no growth” evaluation in collaboration with an experienced neuroradiologist. We used a manual segmentation of the lesion in the transverse FLAIR images (Brain Voyager QX software V.1.2.) [1]. The results are presented in Table 1. We observed a continuous growth with an accelerated growth rate between the 22-month and 32month scans. The volumetric growth in the “no growth” images was approximately 10 % for each time point. The volume increase at 22 months is a 24 % volume increase compared with the index scan, but still unnoticed by crude image assessments. The volume was doubled 32 months after the index scan. The patient had surgery with gross total resection of the tumor. The postoperative recovery was uneventful. Histopathology confirmed a WHO grade 2 astrocytoma. A considerable growth measured in diameters or other crude measures can go unnoticed unless detailed volume estimations are performed. It is also important to remember to use the index MRI as a reference in slow-growing lesions and not only compare the two last scans. In addition, it is important to remember that diffuse lowgrade gliomas grow [3–5], although growth may be difficult to assess in smaller lesions. In suspected or alleged stationary brain lesions followed with subsequent imaging, we suggest performing detailed volume assessments to assess growth. Tools for performing detailed volumetric assessment are now widely available. A. S. Jakola (*) :K. G. Moen :O. Solheim Department of Neurosurgery, St.Olavs University Hospital, 7006 Trondheim, Norway e-mail: asgeir.s.jakola@ntnu.no

Evaluation of the Scandinavian guidelines for head injuries based on a consecutive series with computed tomography from a Norwegian university hospital

BackgroundThis study prospectively assesses clinical characteristics and management of consecutive minimal, mild and moderate head injury patients referred for CT scans. Compliance with the Scandinavian head injury guidelines and possible reasons for non-compliance is explored.MethodsFrom January 16th 2006 to January 15th 2007, 1325 computed tomography (CT) examinations due to minimal, mild or moderate head injury according to the Head Injury Severity Scale (HISS) were carried out at our University Hospital. When ordering a CT scan due to head trauma, physicians were asked to fill out a questionnaire.ResultsGuideline compliance was impossible to assess in 49.5% of all cases. This was due to non-assessable or missing key variables necessary in the decision making algorithm. One or more key variables for HISS classification were not assessable in 34.4% as it was unknown whether there had been loss of consciousness (LOC), duration of LOC was unknown or it was impossible to assess amnesia or focal neurologic deficits. Definite compliance with both CT and admittance recommendations in guidelines was seen in only 31.2%. In 54.2% of patients with minimal head injuries who underwent CT scans, imaging was not necessary according to guidelines. 59.1% of all patients were admitted to hospital, however only 23.7% of these were admitted because of the head-injury alone. Age < 4 years, possible medical cause of injuries, severe headache/nausea or vomiting and the presence of non-traumatic CT findings were independently associated with non-assessable compliance with Scandinavian guidelines. Suspicion of influence of alcohol was inversely associated to non-compliance.ConclusionsDespite the prospective study design, guideline compliance was not assessable in nearly half of the patients. Patients with isolated head injuries and available and obtainable complete clinical information necessary for guideline-based decision making are not dominating in a head injury population.