Table 1.

Patients’ and tumours’ characteristics.

Patient Number	Age (years), Sex	Tumor Grade (Koos, Hannover)	Tumor classification according to the relationship between the LSL and the labyrinth: lateral type (L), on-the-line (O), and medial type (M)	Cisternal Tumor Size (mm)	Intracanal Tumor Extension (%)	HJB (Y/N)	Pneumatized petrous apex (Y/N)
1	33, F	3, T3b	L	20	73	N	Y
2	61, F	3, T3b	M	20	52	N	N
3	49, F	3, T3b	M	27	69	N	N
4	39, M	3, T3b	L	19	59	N	N
5	53, F	3, T2	O	5	76	N	N
6	64, F	3, T3b	L	18	100	N	Y
7	71, F	4, T4b	L	30	73	N	Y
8	63, F	2, T3a	M	11	100	N	N
9	56, F	2, T3a	L	10	44	N	N
10	49, F	3, T3b	L	28	100	N	N
11	75, M	4, T4a	O	31	89	N	N
12	61, F	4, T4b	M	52	44	N	N
13	51, M	1, T1	L	Intracanalicular	87	N	Y
14	47, F	4, T4b	O	51	81	N	N
15	67, F	3, T3b	O	25	77	N	Y
16	56, M	4, T4b	L	3	39	N	Y
17	51, F	3, T3b	O	29	100	N	N
18	66, F	4, T4b	L	40	100	Y	N
19	49, M	4, T4a	L	36	100	N	N
20	49, F	4, T4b	L	45	96	N	N
21	72, M	3, T3a	O	25	100	N	Y

Tumor grade was defined according to Koos and Hannover classifications. The line between the outermost edge of the tumour and the medial side of the sigmoid sinus was defined as the lateral safe line (LSL). According to the relationship between the LSL and the labyrinth, the tumours were classified as lateral type (L), on-the-line (O), and medial type (M) tumours. The intracanal tumour extension was calculated as a percentage of tumour extension along the longitudinal axis of the IAC