All the measurements were performed on a picture archiving and communication system PACS workstation.
The crescentic subdural haematoma having the maximum length the linear distance between the corners of the subdural haemorrhage crescent in any single slice was chosen for HU measurement. To avoid the partial volume effect and to maintain a constant relationship between the diameter of ROI and the breadth of the haemorrhage, a circular region of interest ROI along the maximum breadth of the haematoma was chosen for HU measurement in all cases [ 19 , 20 ]. If the haematoma was present in more than one slice, then the average HU measurement of all those slices were taken as mentioned above.
The HU measurements were measured away from the rim of the subdural haemorrhage to avoid partial volume effect. To assess intra-reader reliability, each reader repeated HU measurements thrice in an individual case with an interval of three weeks between each measurement. Though the scanner and the protocol utilized in the present study, not being state of the art, an attempt was made to determine roughly the effect of the volume of the subdural haematoma on its attenuation. Length was measured as the linear distance between the corners of the SDH crescent.
The breadth was measured as the maximum distance of haematoma from the inner table of the skull perpendicular to the length. The depth was determined by multiplying the number of slices on which haematoma was visible, by the slice thickness. Intra-reader reliability was assessed using the intraclass correlation coefficient ICC. A total of cases in the age group of years were studied. The post-traumatic time interval varied from 0.
The volume of the SDH varied from 0. A crescentic subdural haematoma over the left fronto-parieto-temporal region with a contralateral midline shift. Distribution of cases according to the post-traumatic interval and mean attenuation of subdural haemorrhage. The intra-class correlation coefficient for intra-reader reliability of the first and second readers were 0.
The prediction of PTI was based on density and volume. In logistic regression, after applying forward likelihood ratio method, only density was found out to be significant and is used in the model to predict PTI. The timing of a traumatic event by post-mortem findings carries immense significance for the forensic experts. Multiple methods to determine the age of injury are available which include but not limited to the healing of abrasions, contusions, and other injuries.
The aim of the present study was to determine the post-traumatic interval of the early subdural haematomas based on computed tomography attenuation numbers.
In this study, crescent shaped haemorrhages were distinctively selected to determine the effect of blood volume on attenuation. The variation in density pattern is observed on computed tomography about extravasation of blood with time [ 14 — 16 ]. An acute subdural haemorrhage has a computed tomographic attenuation value that is dependent largely on the proportions of red blood cells, haemoglobin and iron content, and fibrin. An acute thrombus is formed from fibrin, platelets, neutrophils, and red blood cells, and as the cells start losing its integrity, swelling often occurs [ 17 ].
Attenuation also depends on beam energy and may, therefore, differ significantly between different CT scanners. Earlier studies have reported Scanner-dependent variability in CT numbers [ 19 , 22 , 23 ]. However, in Strandberg et al. This contention was avoided in our study by the utilization of a single CT machine with a single standard specification for all the cases. Few studies have been attempted long back for dating the subdural haemorrhage using computed tomography. All the above studies have tried to classify subdural haemorrhage into acute, subacute or chronic depending on the attenuation.
The present study, unlike others, included only early cases of SDH and further differentiation of the haemorrhage according to age was attempted within this short post-traumatic interval. It is pertinent to note that these studies also do not mention the specific radiological methods applied in estimating the age of the subdural haematoma. After about days of the clot formation, the density drops to about 30HU and becomes isodense with the adjacent cortex [ 4 ].
Since the cases in the present study were well within or close to 10 days, all the cases had a high attenuation, which is in concordance with all the above published data. Correlation of attenuation of the haematoma and time interval between injury and computed tomography was found to be highly negative i.
The determination of the post-traumatic interval of the subdural haemorrhage is a complex problem and has been worked out by a very few investigators. Hence a very limited number of studies with which the results of the present study could be compared. These findings accord with the results of other studies examining Intra-reader reliability of attenuation measurements [ 19 ]. Currently, the dating of subdural haemorrhage by measuring the CT number alone could lead to inaccuracies as it depends on measurement technique, object composition, and beam energy. Therefore with further research on this subject, the attenuation of subdural haemorrhages can be measured with more reliability and, thereby placing them accurately into particular post-traumatic interval groups.
However, the outcome of living patients may not be entirely transferable to post-mortem radiology. The application of the current methodology to post-mortem cases will be an oversimplification. Though, the few post-mortem radiological studies conducted previously have inferred minimal difference with the autopsy findings in cases of craniocerebral trauma, not much work has been done on decomposed bodies [ 23 , 24 ].
- Subdural Hemorrhage in Abusive Head Trauma: Imaging Challenges and Controversies?
- Dating of Acute and Subacute Subdural Haemorrhage: A Histo-Pathological Study.
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Further in these studies [ 23 , 24 ], the cases had a time interval of less than 24hours between the death and postmortem radiological examination. These studies concentrated mainly on the gross features rather than going into specifics like aging and the degree of the autolytic process if any. From the radiological point of view, the dating of early SDH remains limited, in the fact that all the SDH were hyper dense, but concurs with the already published data [ 4 , 25 , 26 ]. However, on a further classification of these HU numbers about post-traumatic intervals, information was obtained on the range of attenuation for a particular post-traumatic interval.
Though few studies suggest that dating of subdural haematoma cannot be done accurately using radiological methods [ 25 — 27 ], the present study, yet gives a reliable and a reproducible method for the estimation of the age of early subdural haemorrhage. Not many studies have been conducted recently on the radiological dating of SDH.
Those studies which have dealt with the radiological dating of SDH have not specified the radiological methods and hence the comparison with different studies have been limited. The results from one of the recently conducted questionnaire based study showed that there was a considerable variation among the radiologists, regarding medico-legal opinions on the age of SDH and concluded it unsuitable to use in court because of non-uniformity [ 28 ]. The study was limited by the small sample of materials investigated.
The influence of hypothermia, shock, hypoxia, variations in the blood pressure, the effect of medications during emergency care, potential effects of associated injuries and failure of the internal organs were not evaluated. Repeat CT examinations of the same patient at various times were not done in our study.
Also, a single CT scan machine was used in this study hence variations in attenuation between different CT Scanners could not be appreciated. Because of the difficulty in differentiation into antemortem and postmortem breakdown of cellular components, it is hard to predict the post-traumatic intervals in decomposing bodies. Finally, the CT Scanner and protocol that have been used in this study is not the state of the art concerning its various parameters.
Though single slice CT scanners are not used in state of the art head scans [ 29 ], the constraints on the availability of advanced scanners in a developing country like India, has compelled us to use the resources at hand. Considering a few recent studies being done on the postmortem use of the radiological technologies in the interpretation of the cranio-cerebral traumatic injuries [ 23 , 24 ] one can with some confidence say that these methods hold a lot of stake for the future of radiological autopsy or may indeed replace few of the routinely conducted forensic autopsies of the present times.
The present study has adopted one of the most objective and scientific methods in determining the attenuation of the subdural haematomas in contrast to the other previous studies where none has been applied or has not been mentioned.
Dating of Early Subdural Haematoma: A Correlative Clinico-Radiological Study
Though this study has been limited to the early post-traumatic intervals, it could still grasp some significant findings in the form of variations in the attenuation of the subdural haemorrhage with relation to time of the injury. The attenuation of the acute subdural haemorrhage decreased with increase in the post-traumatic interval. On further classification of these HU numbers about post-traumatic intervals, information was obtained on the range of attenuation for a particular post-traumatic interval.
The variations in the hospital care and treatment, the mode of injuries high velocity , have considerably changed over the years and hence could have contributed to the observed variations despite proper study design. These are also in part due to the dynamic character of such injuries and the various manner in which trauma victims react to an injury.
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Dare to date: age estimation of subdural hematomas, literature, and case analysis.
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- Subdural Hemorrhage in Abusive Head Trauma: Imaging Challenges and Controversies.
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Find articles by Suresh Kumar Sharma. Author information Article notes Copyright and License information Disclaimer. This article has been cited by other articles in PMC. Abstract Introduction Determination of post-traumatic interval remains one of the foremost important goals of any forensic investigation related to human crimes. Materials and Methods The study included a total of cases of closed head injury with subdural haemorrhage. Results Statistically significant results were obtained between the HU measurements of the SDH and the post-traumatic intervals and were found to be statistically significant.
Conclusion The density of the subdural haematoma decreases with increase in the post-traumatic interval that concurs with the limited number of studies being conducted in the past. Attenuation coefficient, Computed tomography, Post-traumatic interval, Subdural haemorrhage, Volume. Typically crescent-shaped, they are usually more extensive than extradural hematomas. In contrast to extradural hemorrhage , SDH is not limited by sutures but are limited by dural reflections, such as the falx cerebri , tentorium , and falx cerebelli.
Classical teaching is that it is located in the potential space between the arachnoid layer and inner layer of the dura; however, no such space really exists. Rather the arachnoid-dura junction is composed of "avascular tissue with flake-like [ Bleeding occurs within this multicellular layer, with these cells located on both sides of the hematoma This possibly accounts for why some acute hematomas appear to have multiple compartments, usually ascribed to intermittent bleeding ref required.
Common sites for subdural hematomas are frontoparietal convexities and the middle cranial fossa. In the vast majority of cases, CT scans are sufficient to make the diagnosis and manage these patients. Contrast is sometimes helpful if there is the concern of a subdural empyema, of the presence of a small isodense subdural, or to try and distinguish enlargement of the extra-axial CSF space from a chronic subdural hematoma.
In most instances, patients are not imaged in the hyperacute phase first hour or so , but on occasion when this is performed they appear relatively isodense to the adjacent cortex, with a swirled appearance due to a mixture of the clot, serum and ongoing unclotted blood 4. There is often a degree of underlying cerebral swelling especially in young patients where head trauma is often more severe which accentuates the mass-effect created by the collection 4. The classic appearance of an acute subdural hematoma is a crescent-shaped homogeneously hyperdense extra-axial collection that spreads diffusely over the affected hemisphere.
Rarely, acute SDHs may be nearly isodense with the adjacent cerebral cortex. Patients with a deficient coagulation can also demonstrate a hematocrit fluid-fluid level as the blood does not form a clot and red cells have time to drift dependently 4. In patients with underlying low hemoglobin and platelets conditions such as sickle cell anemia , acute subdural hemorrhage may be hypodense even in the acute phase As the clot ages and protein degradation occurs, the density starts to drop. The key to identification is visualizing a number of indirect signs, including:. Rarely, the periphery of the SDH may calcify, see calcified chronic subdural hematoma for an in-depth discussion regarding the CT appearance of this entity.
Acute on chronic subdural hematomas refers to a second episode of acute hemorrhage into a pre-existing chronic subdural hematoma. It typically appears as a hypodense collection with a hematocrit level located posteriorly. A similar appearance can be seen in patients with clotting disorders or on anticoagulants 4. The appearance of a hematoma varies with the biochemical state of hemoglobin which varies with the age of the hematoma.
Dating of Acute and Subacute Subdural Haemorrhage: A Histo-Pathological Study
It may appear biconvex-shaped on the coronal plane rather than crescent-shaped which is a typical appearance on the axial plane. Treatment depends primarily on the amount of mass-effect and neurological impairment caused by the collection, and thus correlates with the size of the subdural hemorrhage. Small collections — so-called 'smear subdurals' — especially those which are chronic and are not causing symptoms can be observed with serial CT scans. Symptomatic collections need to be surgically evacuated. In the acute setting, this should be performed rapidly within 4 hours 3 and usually requires a craniotomy as the clot is not easily evacuated via burr holes.
The compressed brain can take some time to re-expand, and subdural collections may re-accumulate. To quiz yourself on this article, log in to see multiple choice questions. You can also scroll through stacks with your mouse wheel or the keyboard arrow keys. Unable to process the form. Check for errors and try again. Thank you for updating your details.