Categorization and distribution of patients with CSF leak identified on GdM

	No. of Patients	CSF Leak on GdM (% of Patients in Group)
Group 1: No CSF leak on CTM with at least 1 imaging study with positive findings
Group 1a: Classic brain MR imaging with diffuse dural enhancement and brain sag	14^{^a}	2 (17%)
Group 1b: Extradural fluid collection on MR spine imaging	2^{^a}	1 (50%)
Group 2: No CSF leak on CTM with equivocal brain imaging (dural enhancement without brain sag or brain sag without dural enhancement) and negative findings on spine imaging	3	1 (33%)
Group 3: No CSF leak on CTM and negative findings on MR brain and spine imaging	6	1 (14%)
Group 4: Known CSF leak seen on CTM	17	12 (71%)
Total number of patients in groups 1–4	41	17 (41%)

↵a One patient without a leak had both classic brain MR imaging and extradural fluid and is included in both groups 1a and 1b.