The Neuroradiology Journal 19: 569-576, 2006

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Early Brain Spect in Patients after Minor Craniocerebral Trauma W. MARKS*, J. LASEK*, Z. WITKOWSKI*, P. LASS**, W. DEJA*, M. BIAŁKO*, M. STASIAK* * Department of Trauma Surgery, Medical University of Gdańsk; Poland ** Department of Nuclear Medicine, Medical University of Gdańsk; Poland

Key words: focal perfusion deficits, minor craniocerebral trauma, regional cerebral blood flow, single photon emission computed tomography

SUMMARY – A prospective study made 57 measurements of cerebral blood flow (CBF) by Single Photon Emission Computed Tomography (SPECT) in post-traumatic patients. The aim of the investigation was to evaluate CBF in patients after minor craniocerebral trauma (mCCT) to ascertain the clinicotopographic correlation of the CBF changes, and to study SPECT in comparison with computed tomography (CT) findings. In addition, evaluation of the usefulness of SPECT for forensic medicine, assessment of secondary brain injury by SPECT and the predictive value of hypofrontalism were performed. A direct correlation was shown between mCCT and the observed CBF disorders, and between the CBF disorders and clinical symptoms as well as better SPECT sensitivity in comparison with CT. The usefulness of SPECT for forensic medicine purposes was also shown. Secondary brain injuries were disclose and the predictive value of hypofrontalism was confirmed. No correlation between GCS and CBF changes was found.

Introduction Craniocerebral trauma (CCT) is the most frequent result of serious trauma, especially following traffic accidents. Patients after CCT need to be hospitalised mainly in case of diagnostic uncertainty. In the USA 60% of patients experience minor injuries after head injury 9. A post-traumatic syndrome develops in about one third of patients and 11-15% patients cannot return to work after trauma 5. Not only do patients with severe CCT create considerable diagnostic, economic and legal problems, but this also applies to those with mCCT who are defined as having brain concussion 5. Most authors accept values between 13 and 15 points on the Glasgow Coma Scale (GCS) as a criterion qualifying patients as mCCT 2. Nowadays CT and MRI are the most important diagnostic methods recommended in patients following CCT. These methods are recognised as sensitive and specific enough in severe injuries but not sufficient in mCCT.

Examination by means of SPECT was introduced to diagnose mCCT in the early 1980s. The method is based on recording the radiation emitted by isotopes (e.g. technetium) using gammacameras and the computed reconstruction and imaging of thin layers of the examined organ. Depending on the mechanism of head trauma the patient experiences acceleration, deceleration or rotation. In the case of injury to a motionless head (assaults) acceleration causes damage to the cortex and subcortical structures close to the soft tissue injury (contusion of the scalp), without distance changes - contre-coup 10. In cases of acceleration and deceleration typical changes are present below the soft tissue injury and in the opposite area (road traffic accidents and falls). Rotational acceleration acting in many directions causes disseminated (multifocal) changes 10. A clinical consequence of traumatic brain injury is brainstem concussion. This may result in temporary loss of reticular formation func569

Early Brain Spect in Patients after Minor Craniocerebral Trauma

tion and blocking of reticular-thalamic-cortical junctions which finally cause disorders or loss of consciousness. One of the most important consequences of mCCT is changes to cerebral blood flow (CBF). Total blood flow in the cerebral vascular bed is about 55-60±5 ml/100g tissue/minute. Wellfunctioning autoregulation mechanisms are necessary to maintain physiological CBF. Nearly 30% of patients develop changes to CBF after mCCT due to impaired autoregulation. Autoregulation of CBF may affect both traumatized areas and regions distant from the initial injury site. Dysfunction of brainstem structures may be responsible for pathological autoregulation. Constriction of blood vessels may be another cause of CBF decrease. CBF changes caused by diffuse axonal injury (DAI), mainly due to rotational-acceleration mechanisms with a multifocal pattern, are found in some 30% of patients after CCT 4. Another theory explaining rCBF changes and the presence of focal perfusion deficits (FPDs) assumes the existence of selective neuronal loss. Particular susceptibility of the frontal lobes to a diffuse reduction of perfusion probably results from its vascularization by long terminal branches of the anterior and middle cerebral arteries and also from their specific cytoarchitecture 4. The aim of the study was to: 1. Evaluate SPECT as an enhancing and complementary diagnostic method in patients after mCCT and establish a possible correlation between clinical symptoms and disturbances of CBF. 2. Assess the usefulness of SPECT in forensic medicine. 3. Evaluate early post-traumatic secondary brain injuries and assess the predictive value of hypofrontalism by SPECT. Material and Methods During 12 months (from 1.5.1997 to 30.4.1998) 495 patients were admitted to the Department of Trauma Surgery because of CCT. Out of 454 patients with isolated head injuries 31 were studied by SPECT of whom six were women (19.4%) and 25 men (80.06%); with an average age 34.8 years (range 18 - 75 years). A control group consisted of 26 people (17 women and 9 men) aged 20-74 years (average 42.1) who were healthy volunteers, mostly medical personnel from our University. 570

W. Marks

Fifty-seven studies of CBF with SPECT were performed. Post-traumatic patients and controls agreed in writing to be examined after having been informed about the purposes of the study and possible side effects. The project was approved by the Local Ethical Committee of the Medical University of Gdańsk (MUG). SPECT examinations were carried out by the Department of Nuclear Medicine, MUG. Studies were carried out in the head-injured group up to the 14th day after trauma (on average after 8.81±4.38 days). Only patients diagnosed mCCT were included (i.e. persons with initial GCS≥13, mean value 14.39±1.26). All patients experienced closed head trauma without injuries in other regions. In 24 patients various autonomic symptoms were recorded (bradycardia, tachycardia, bradypnoea, tachypnoea, changes in systolic blood pressure, nausea, vomiting, dizziness). Neurological deficits (paresis, pyramidal symptoms, nystagmus, central hypoacusis, motor aphasia, diplopia, focal paraesthesia, cerebellar ataxia) were observed in 12 patients. Thirty CT scans were performed in 20 patients. Before the study the patients stayed in a dark quiet room for 20 minutes. A tomographic CBF examination was performed 20 minutes later following an intravenous injection of technetium-99m linked with HMPAO (Amersham, UK) of 20 mCi activity (740 MBq) was injected intravenously. Triprobing Multispect-3 gammacameras (Siemens, Erlangen, Germany) equipped with a special collimator for neurological examinations (Neurofocal) were used. Acquisition and reconstruction of images was performed with an ICON computer (Siemens). Two independent observers, ‘blind’ to clinical details, carried out a qualitative evaluation to identify the areas of decreased perfusion. Focal perfusion deficits (FPDs) have been defined as local blood flow changes measured by means of AI (Asymmetry Index; AI=(R-L/(R+L)/2x100%). For each focus identified by quality analysis as hypoperfused a semi-quantitative analysis was carried out with AI. Regional CBF deficit was recorded as a diffuse symmetrical decrease of blood flow measured by the comparison of regional versus cerebellar radiotracer uptake. Hypofrontalism was defined as a decrease in rCBF of the frontal lobes below the mean ± SD value of rCBF of the frontal lobes of the control group. The traumatized area (the site of trauma) was identified on the basis of soft tissue injuries and anamnesis. Statistical analysis was performed with a

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Figure 1 Regional cerebral blood flow (rCBF) on the left side compared to the control group.

The Neuroradiology Journal 19: 569-576, 2006

Figure 2 Regional cerebral blood flow (rCBF) on the right side compared to the control group.

Figure 3 Brain SPECT. Disseminated (multifocal) pattern of the FPDs.

Statistics programme for Windows. Normality of distributions and equality of variances in the examined groups were checked by a ShapiroWilk test and an equality of variances test. For a further analysis Kruskal-Wallis’s test was used. In order to evaluate the dependence between the amounts under examination the nonparametric Spearman’s test was used. A level of p

Early brain spect in patients after minor craniocerebral trauma.

A prospective study made 57 measurements of cerebral blood flow (CBF) by Single Photon Emission Computed Tomography (SPECT) in post-traumatic patients...
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