Acute mild traumatic brain injury, pre-injury health and structural imaging findings

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Arvo building, Jarmo Visakorpi auditorium, address: Arvo Ylpön katu 34.

Harri Isokuortti

Doctoral defence of Lic.Med. Harri Isokuortti

Acute mild traumatic brain injury, pre-injury health and structural imaging findings

The field of science of the dissertation is Neurosurgery.

The opponent is professor Joukje van der Naalt (University of Groningen, Netherlands). Professor Juha Öhman acts as the custos.

The language of the dissertation defence is English.

Traumatic brain injury patients are often elderly and have comorbidities, but CT scan reveals intracranial trauma and who need observation

Traumatic brain injuries (TBI), especially mild traumatic brain injuries (MTBI), are common and often seen in the emergency rooms. Traumatic brain injury patients are a heterogeneous group, i.a. in terms of age, pre-injury diseases and trauma mechanism. Serious complications are rare after MTBI, but the incidence of complications after a normal head CT is not well known. In Finland, it has been customary to hospitalize head injury patients for observation or discharge them with written instructions.

The patient pool for this study consisted of all patients who were treated at the emergency department (ED) of the Tampere University Hospital (2010-2012) and who underwent head CT after a HI (N=3,023). The main objective was to describe the pre-injury health and intracranial acute and chronic imaging findings in head injury patients. The assosiation of certain pre-existing cerebral diseases and injury severity was assessed. One of the original publications focused on the incidence of delayed complications. Additionally, the selection bias in MTBI studies was studied by evaluating the effect of different exclusion criteria on the patient enrollment.

Of all patients, 1,990 (66%) met the MTBI criteria, 257 (9%) had a more severe TBI, and 776 (26%) had a head injury without obvious signs of TBI. In these three groups the most common pre-injury diseases were circulatory (39-43%), neurological (24-25%), and psychiatric (26-28%) disorders. Alcohol abuse was present in 18-27%. The most common medications were for cardiovascular (33-37%), central nervous system (21-31%), and blood clotting and anemia indications (22-23%).

Most of the patients who sustained an MTBI had some pre-injury diseases or conditions that could affect clinical outcome. Only 2.5% of the screened patients met all the enrollment criteria. Age, neurological and psychiatric conditions were the most common reasons for exclusion. Pre-existing brain lesions were common in the MTBI patients and the incidence increased with age. By excluding patients with pre-existing conditions, the patients with known risk factors for poor outcome remain poorly studied.

The pathological changes seen within the MTBI classification are heterogeneous. The most common traumatic lesions were subdural hematomas, subarachnoid hemorrhages, and contusions. Every sixth (16%) MTBI patient had an intracranial lesion, compared to 5/6 (86%) in the moderate to severe TBI group. Having a past traumatic lesion was associated with increased risk for an acute traumatic lesion. Lower GCS, male sex, older age, falls, and chronic alcohol abuse were associated with higher risk of acute intracranial lesion in MTBI.

The majority (n=1811, 74%) of the patients with a negative head CT were discharged home and none had delayed complications. Of the 632 (26%) CT-negative patients admitted to the hospital ward from the ED, a head CT was repeated in 46 (7%) patients and only one patient had a traumatic intracranial lesion. This lesion was not life-threatening and did not need any neurosurgical intervention. The overall complication rate was 0.04% and mortality rate 0%. This study with unselected HI patients suggests that the probability of delayed life-threatening complications was negligible when the primary CT scan revealed no acute traumatic lesions.


The dissertation is published in the publication series of Acta Universitatis Tamperensis; 2328, Tampere University Press, Tampere 2017. The dissertation is also published in the e-series Acta Electronica Universitatis Tamperensis; 1832, Tampere University Press 2017.

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