Table 4. The addition of spinal fluid drainage (SFD) to assisted circulation, Crawford’s technique of cross clamp without AC, and hypothermic arrest has significantly reduced paralysis risk. This is also true for endovascular procedures.

Group	Total Patients	O/E Ratio	% Deficit	P-value
Assisted circulation	1,386	1.03	15.4	<0.0001
Assisted circulation + SFD	5,773	0.24	4.3
Cross clamp	4,485	0.91	13.9	0.0013
Cross clamp + SFD	1,384	0.23	4.1
Hypothermic arrest	399	0.42	6.7	0.0065
Hypothermic arrest + SFD	463	0.15	2.8
Endovascular procedures	733	1.12	6.9	0.0459
Endovascular procedures + SFD	1,423	0.61	4.2