Model of Closed Head Injury in Rats - Experimental Study

Objective: The objective of this study is to create a reproducible model of closed head injury in rats using the acceleration-deceleration mechanism, The model should result in increased intracranial pressure (ICP) and neurological deterioration animals, and generate graded brain injury. Material and method: In order to provoke cranial traumas we constructed an impactor with selectable weights and a mobile impact surface, Within the first pilot group of 40 rats, we tested only its basic setup. Afterwards, within the second group of 21 rats, we provoked an experimental cranial trauma using a weight of 400 grams dropped from a height ranging from 30 to 100 centimetres at a constant surface elasticity. Within the third control group of 15 rats, we measured physiological parameters including ICP. Results: According to the height of fall, four types of brain injuries were established - lethal, severe, moderate, and mild. With the lethal injury (45-100 cm), an immediate convulsions with subsequent death occurred in all the rats. A severe injury (40 cm) showed 50% mortality. Neurological deterioration and an average ICP of 9.3 +/- 3.76 mmHg was recorded in the surviving animals. A moderate brain injury (35 cm) resulted in lower mortality, the neurological deficit occurred in half of the survivors and ICP achieved 7.6 +/- 3.54 mmHg. Within the group of mild brain injury (30 cm), all animals survived without any neurological and behavioral deterioration with an ICP of 5.5 +/- 0.74 mmHg. The control group without any injury had an ICP of 2.9 +/- 0.81 mmHg. Conclusion: The described model of closed head injury in rats using a modified impactor with adjustable weights is suitable for both single-stage and two-stage experiments examining craniocerebral injuries. By simply changing the fall height of the impactor, reproducible severe, moderate, or mild brain injury can be created. The intracranial pressure elevation and the neurological deterioration correlate with these grades of brain injury.