Study year

Approach

No of patients

Follow up period

Facial nerve preservation

Extent of tumour resection

Harner, 1987 [32]

Retrosigmoid

48 in each group

3 months

Anatomically:

88% in monitored versus

79% in non monitored

Functionally: tumours 2-4 cm; 40% of monitored has excellent function versus 17% in non monitored.

In tumour > 4 cm 38% was paralyzed in monitored versus 90% in non monitored

Not reported

Harner, 1988 [33]

Retrosigmoid

91 in each group

12 months

Functionally: 92% in monitored versus 84% in non monitored

Not reported

Leonetti, 1989 [34]

Infratemporal

20 in the monitored group,

31 in the non monitored

Immediate postop

Functionally:

93% in monitored versus 70% in non monitored

Not reported

Hammerschlag and Cohen, 1990 [35]

Translab,

Suboccipital

111 in the monitored group,

207 in the non monitored

Immediate postop

Functionally:

3.6% has paralysis in monitored group versus 14.5% in non monitored group

Not reported

Taddi, 2016 [23]

Retrosigmoid

27 in the monitored group,

24 in the non monitored group

12 months

Anatomically:

100% in monitored versus

91% in non monitored

Functionally:

	monitored	non-monitored
Grade I, II	66.7%	13.6%
Grade III, IV	33.3%	63.6%
Grade V, VI	0%	22.7%

100% Complete resection

Current study, 2021

Retrosigmoid

15 in each group

6 months

Anatomically:

100% in monitored versus

93.3% in non monitored.

Functionally:

	monitored	non-monitored
Grade I, II	93.3%	66.7%
Grade III, IV	6.7%	20%
Grade V, VI	0%	13.3%

	GTR	NTR	STR
Monitored	66.7%	13.3%	20%
Non- Monitored	86.7%	6.7%	6.7%