neurosurgery resident presentation

1. DR.MUMTAZ ALI
JPMC KARACHI

2. INTRODUCTION
 neuromas or neurinomas
 most common lesion at CPA
 6% to 8%
 benign

3. HISTORY
 neuroma : Virchow => cochlear nerve
 Schwann cells => vestibular division => vestibular
schwannoma (1992)
 1777, Sandifort => 1st medical report of VS
 1830 ,Charles Bell => accurate description
 19th century, Babinski and Jackson => accurate
localization

4.  Von Bergmann => 1st surgery(1890)
 1894 by Balance => 1st successful surgery
 unilateral suboccipital craniectomy , Woosley in 1903
 translabyrinthine approach
 Cushing’s writings
 surgical microscope => 1961 by William
 20th century : 86% => 20% by Harvey Cushing

5.  House => 10%
 Modern-era =>0.8% and 5%
 1969 , Lars Leksell and Bjorn Meyerson => 1st Gamma
Knife

6. EPIDEMIOLOGY
 1.6 per 100,000 annually
 mean age : 58 years
 both sexes are affected equally
 high-dose ionizing radiation
 Sughrue and colleagues ,growth rate > 2.5 mm/yr
 Stangerup and Cayé-Thomasen :
intrameatal tumors : 83%
extrameatal extension : 17 %

7.  rate of hearing preservation : wait-and-watch approach
 Cystic lesions => sudden and dramatic growth =>higher
rates of facial palsy =>reduced rates of hearing
preservation
 Solid lesion => slow & gradual => dec rate of facial palsy =>
inc rate of hearing preservation
 25% : observation
 microsurgical resection : 90% to 53%
 radiosurgery : 5% to 24%

8. ASSOCIATION : NF2
 1822, Wishart => bilateral VS => NF-2
 sporadic cases of VS => tumor occur unilaterally
 NF-2 => bilateral VS
 Faster growth rate
 Early age
 1 in 35,000,

9.  autosomal dominant
 22q12.2
 merlin protein
 2015 : 9 clinical trails
 bevacizumab

10. DIAGNOSTIC CRITERIA :NNFF
 Probable NF2:
 Unilateral VS and age less than 30 years plus one:
meningioma, glioma, schwannoma, juvenile posterior
subcapsular lenticular opacities, or cortical cataract
Two or more meningiomas plus
Unilateral VS and age less than 30 years or
One of the following: meningioma, glioma,
schwannoma, juvenile posterior subcapsular lenticular
opacities, or cortical cataract

11.  Definite NF2:
 Bilateral VS or
 First-degree relative with confirmed NF2 plus
Unilateral VS and age less than 30 years or
Any two of the following: meningioma, glioma,
schwannoma, juvenile posterior subcapsular lenticular
opacities, or cortical cataract

12. HISTOPATHOLOGY
 Obersteiner-Redlich zone : transition point between
glial and Schwann cells
 90% : inferior division of the vestibular nerve
 well-circumscribed, encapsulated lesions that splay

13.  Gross Appearance :
Rubbery
gray and yellowish areas
hemorrhage and cyst formation

14. • Microscopic features :
Antoni A: compact spindle cells with elongated nuclei
& ample pink cytoplasm
Antoni B : loosely arranged cells with multipolar
processes & microcyst formation
Verocay bodies :alternating arrangment of palisading
nuclie & cell bodies
S-100 & vementin

15. CLINICAL FEATURES

16. INVESTIGATIONS
 Routine :
Cbc
Suce
PT/APTT/INR
Chest x-ray
Hep B & C
LFT
ECG
Echo

17.  Specific :
CT scan brain
MRI brain with contrast
• Relevant :
CT angiogram
MRV
Rinne’s test
Weber test
Pure tone audiometry

18. RADIOLOGY
 trumpeted internal acoustic meatus [IAM] sign
 ice-cream cone appearance
 CT scan :
 often erosion and widening
solid portion : isodense
cystic portions : hypodense
beam hardening artifact
Calcifications are rarely seen

19.  MRI :
T1 : 2/3 : hypointense,
T2 : hyperintense
Contrast T1 : enhancement
• CT Angiogram :
>4 cm

25. AIMS OF TREATMENT
 quality of life
 hearing
 facial nerve function
 Serviceable hearing : 50/50

26. INTRAOPERATIVE MONITORING
 VII CN monitoring
 VIII CN monitoring
 Brain stem auditory evoked responses
 Direct chochlear nerve action potential monitoring

27. SURGICAL APPROACHES
 retrosigmoid (RS)
 MCF
 translabyrinthine (TL)
 Main factors:
 tumor size
 extent of cisternal versus intracanalicular growth
 baseline hearing function
 patient preference
 surgeon’s preference and comfort level

28. Ansari & co-workers :2012
 Hearing preservation:
 <1.5 cm, MCF :43.6% ,RS : 64.3% , p < .001
 serviceable hearing : 63% to 88%
• Facial nerve dysfunction:
intracanalicular tumors , RS : 4% ,MCF: 16.7% p < .001
<1.5 cm, MCF :3.3%,TL: 11.5%, RS: 7.2%, p = .001
1.5 to 3.0 cm, the RS :6.1% , MCF: 17.3%, TL :15.8%
>3.0 cm , RS :30.2% , TL: 42.5%, p < .001
 Complications :
CSF leak : RS group:10.3% ,MCF : 0% , TL :8%,p <.001

30. RECTOSIGMOID APPROACH
 INDICATIONS :
Work horse : skull base surgery
anterolateral posterior cranial fossa
Rapid & easy access to CPA
larger tumors with brainstem compression
intracanalicular tumors with good hearing
“minimally invasive” endoscopic approach

33. TECHNIQUE
 supine position , head turned to the contralateral side
 shoulder roll is avoided
 not overrotate the head
 Pressure points : padded
 1 g/kg of mannitol, cefazolin 2g, dexamethasone 10mg
 Intraoperative monitoring
 intracanalicular component : a curvilinear incision
 Cisternal part : small craniotomy thru linear incision
 dissection

34.  curved cerebellar retractor
 Neuronavigation
 drill away the outer table
 exposing the dura of the posterior cranial fossa
 Air cells of the mastoid
 C-shaped dural opening
 operating microscope
 facial nerve
 internal debulking

35.  Tumor resection
 Facial nerve
 Hemostasis
 Duroplastry : bovine pericardium patch
 Copious irrigation with antibiotic solution
 Wound closed in layers
 24 hours observation in icu
 MRI next morning

37. MIDDLE CRANIAL FOSSA APROACH
 dominant intracanalicular component
 small or absent cisternal component
 hearing preservation
 temporal retraction : seizures

39. TECHNIQUE
 Mayfield head holder
 squamous part of the temporal bone : parallel
 floor of MCF : vertical
 Mannitol : 1g/kg , cefazolin 2g, dexamethasone 10mg
 Neuromonitoring
 lumbar puncture or lumbar drain
 horseshoe incision
 squamous part of the temporal bone

40.  4-cm × 4-cm craniotomy
 1/3 : anterior to EAM , 2/3 : posterior to EAM
 operating microscope
 Bleeding
 Direct stimulation
 IAC location
 Drilling

41.  entire labyrinthine segment of the facial nerve
 tumor is mobilized
 cochlear nerve
 vestibular nerve
 labyrinthine artery
 Hemostasis
 abdominal fat
 exposed air cells

42.  Dural closure
 temporalis muscle : 0.5% bupivacaine
 Wound
 24 hours observation
 MRI next morning

43. TRANSLABYRINTHINE APPROACH
 good outcomes in experienced hands
 Hearing
 large tumors
 no serviceable hearing
 facial nerve
 transosseous nature
 lack of cerebellar retraction
 limited access : CPA ,foramen magnum ,jugular
foramen

44. TECHNIQUE
 Supine , head turned to oposite
 shoulder roll : ipsilateral shoulder
 squamous part of the temporal bone : parallel
 C-shaped incision
 dissection
 myocutaneous flap
 labyrinthectomy
 IAC is exposed

45.  dura is opened
 intracapsular debulking
 tumor resection
 risk to the pons and the facial nerve
 hemostasis
 Wound
 24 hour
 MRI

48. STEREOTACTIC RADIOSURGERY
 1971 by Leksell
 an incision
 Hospitalization
 little immediate morbidity
 facial palsy, hearing loss, vestibular dysfunction
 facial spasm, facial numbness, cerebral/brainstem
edema, and hydrocephalus
 excellent local tumor control

50. COMPLICATIONS
 Intraoperative :
 Facial nerve injury : proximal to geniculate ganglion
 Chochlear nerve injury: vasoactive agent => nimodipine
 Vascular injury
 Postoperative :
 HCP : 18%
 Headache : 1/3
 CSF leak : 8-30%
 Infections
 DVT
 Meningitis

51. THANK YOU.