Neck Flexion Induces Larger Deformation of the Brain Than Extension at a Rotational Acceleration, Closed Head Trauma

Table 1

Number of animals, exposures and results.

Impact condition, number of animals^1	Acceleration (krad/s^2)			Location of transducer	Animals,	Tests,	Peak Pressure (bar)
	Mean	Std. dev.^4					Mean^4	Std. dev.^4
High Flexion^3	208,0	n.a.	1	Brainstem	1	1	−0,47	n.a.
				Basal ganglia	1	1	n.a	n.a.
Low Flexion	96,3	15,0	52	Brainstem	7	48	−0,38	0,20
				Basal ganglia	6	30	−0,49	0,16
				Paraflocculus	1	3	−0,20	0,05
				Cerebellum	1	1	−0,15	n.a
				Angled in Basal ganglia	1	12	—	—
High Extension	−184,5	14,5	20	Brainstem	3	6	0,29	0,10
				Basal ganglia	4	8	0,34	0,18
				Hippocampus	6	13	0,62	0,24
				Parieto-temporal cortex	5	12	0,48	0,34
Low Extension	−95,0	6,6	37	Brainstem	4	8	0,51	0,15
				Basal ganglia	4	18	0,30	0,16
				Hippocampus	8	24	0,25	0,14
				Parieto-temporal cortex	8	23	0,33	0,19

The total number of animals exposed to sagittal rotational acceleration impulses was 24. Three animals were exposed to a single high level flexion tests, one animal was exposed to multiple low and high level flexion tests and four animals were exposed to multiple low level flexion tests. Three animals were exposed to multiple low level extension tests, six animals were exposed to multiple low and high level extension tests, three animals were exposed to a single high level extension test and one animal was exposed to multiple high level extension tests. Finally, three animals were exposed to multiple low level flexion and extension tests.
²The total number of experiments that provided useful data was 110.
³The three animals that were exposed to a single high level flexion tests did not provide peak pressure data. All transducers installed bottomed out; the underpressure was as least in the range of −0.45 bar. As such these test confirm the data provided by the single test that provided brainstem pressure data.
⁴n.a.: not available.