الفهرس 
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Abstract
This study is a prospective hospital based case series conducted on
356 patients during the period from May 2018 to December 2019, at
Tokyo Medical University Hospital to address the safety and the efficacy
of surgical management of Vestibular Schwannoma and importance of
intraoperative neurophysiological monitoring.
Patients included with unilateral vestibular schwannoma, with or
without hydrocephalus and received preoperative radiotherapy or not.
Clinical assessment was done through medical history, general
examination and neurological examination
Investigations were done as lab, MRI and audiological assessment.
Surgical excision of vestibular schwannoma through retro-sigmoid
approach to the posterior fossa is the main surgical technique as it gives a
wide view of the posterior fossa. Intraoperative facial nerve monitoring
and auditory brain stem monitoring seem to decrease morbidity of
surgical intervention.
All patients will be followed up postoperatively, during hospital stay.
Regarding Pre-operative data: We found that the results was follow:
Age of all patients was (42.57 ± 12.3) years. Regarding gender of
the patients, the majority (54.8%) of patients were females; while
(45.2%) were males.
The average size of tumour was (28.75 ± 9.7) mm; with (50.8%) of
patients had Lt-sided tumours, (47.8%) had Rt-sided tumours, and
(1.4%) had bilateral tumours.
KOOS classification; the average size of tumour was (28.75 ± 9.7)
mm; with (20.2%) of patients had grade 2 tumour, (34.6%) had grade 3
tumour, and (45.2%) had grade 4 tumour.
Hannover classification; (69.6%) of patients had large tumours, and
(3.4%) had small and medium tumours.
Regarding presenting (initial) symptoms; (64.6%) of patients
presented with Hearing loss, (73.3%) presented with Tinnitus, (53.7%)
presented with Face numbness, (2.2%) presented with Imbalance,
(57.6%) presented with Dizziness or vertigo, (6.7%) presented
Incidentally, (1.4%) presented with Facial paralysis, and (1.1%)
presented with Trigeminal neuralgia.
The average PTA “degree of hearing loss” was (39.72 ± 24.66) dB;
with (29.9%) of patients had A “≤ 30 dB” degree, (56%) had B “> 30 ≤
50 dB” degree, (2%) had C “> 50 dB” degree, and (52.4%) had D
degree
Hearing loss type; (10.1%) of patients were normal, while (7%)
had Cochlear hearing loss, (25%) had retro-cochlear hearing loss,
(52.2%) had mixed hearing loss, while (5.6%) had unknown type of
hearing loss.
Origin prediction on MRI; (38.8%) of patients had inferior origin,
(40.7%) had superior origin, and (20.5%) had unknown origin.
Facial nerve preservation; (98.6%) of patients had preserved
function, (0.3%) had lost function, and (1.1%) were morphological.
Cochlear nerve preservation; (14.4%) of patients had preserved
function, (66.7%) had lost function, (18.6%) were morphological,
while (0.3%) had originally absent nerve.
Pre-operative facial nerve function; (93.8%) of patients had none
(0-HB) grade, (3.1%) had (2-HB) grade, (1.7%) had (3-HB) grade,
(0.3%) had (4-HB) grade, (0.8%) had (5-HB) grade, and (0.3%) had (6-
HB) grade.
Regarding Intra-operative data: We found that; the average Resection
ratio was (96 ± 4.5) %; with (16.7%) of patients had total resection,
(69.2%) had near total resection, and (14.1%) had subtotal resection.
Comparative study between pre and post-operative facial nerve
function revealed; highly significant increase in HB-1 grade, in postoperative
assessment; compared to pre-operative assessment of facial
nerve functions; with highly significant statistical difference (p < 0.0001).
Pearson’s correlation analysis shows that;
Age, size of tumour and degree of hearing loss, had a
highly significant positive correlation with post-operative
HB grade; with highly significant statistical difference (p <
0.01 respectively).
Resection ratio had a highly significant negative
correlation with post-operative HB grade; with highly
significant statistical difference (p < 0.01).
Multiple regression analysis shows that; after applying (Forward
method) and entering some predictor variables; the increase in age, and
the decrease in resection ratio; had an independent effect on increasing
post-operative HB grade; with significant statistical difference (p < 0.05
respectively).
RECOMMENDATIONS
Complete microsurgical tumour removal is the optimal
management for patients with growing VS. The procedure is safe,
associated with favourable facial nerve outcome, and may also improve
existing neurological symptoms.
The retro-sigmoid suboccipital approach to the skull base can be
safely and successfully achieved using a microsurgical technique, with
minimal or no damage to neurovascular structures, even for large
tumours.
The management goals of vestibular schwannomas have shifted
from total resection to functional preservation.
As shown in our work regarding the special importance of
intraoperative neurophysiological monitoring to improve the outcome of
CPA lesions, we would emphasise the great need to get hands on such
equipment in our institutions.
Special attention should be given regarding training of junior
neuro-surgeons on surgical approaches and new microsurgical techniques
considering the long steep learning curve for skull base surgeries
specially CPA.
CONCLUSION
Surgical management of Vs using retrosigmoid approach is safe and
effective but after advancement of microsurgical techniques like drilling
and neurophysiological monitoring specially for seventh and eighth
cranial nerves, the possibility of preserving the fascial and cochlear
functions became more feasible with excellent results.
We found also, that the age of the patient, size and consistency of the
tumour, degree of intra-meatal extension, duration of symptoms, and
resection ratio have a highly significant correlation with patients`
outcome specially facial nerve function.