1. Minimally Invasive Skull Base Surgery: Fact or Fantasy?
Hrayr K. Shahinian M.D,FACS
SKULL BASE INSTITUTE

2. A Need for Improvement... Limitations of posterior fossa microscopy
visualization limited to direct anterior-posterior axis
shallow depth of field
“static” imaging

3. A Need for Improvement... Limitations of posterior fossa microscopy
clinical implications for MVD
missed conflicts
inadequate decompressions; recurrence
clinical implications for pituitary surgery
residual tumor in lateral recesses of sella turcica

4. Technological Advancement
Rigid endoscopes
varying widths
varying angles of view
Cameras
single-chip
three-chip
digital
three-dimensional

5. Technological Advancement
Light sources
halogen
metal halide
xenon arc
Recorders/processors
digital
Irrigation sheaths
Holding arms

6. Animal Experimental Models
Allow for preliminary evaluation of the effectiveness of the new procedure
Can be reliably reproduced to increase familiarity with new instruments in a safe and controlled setting
Provides a means for surgical training before application in the operating room

7. Animal Experimental Models
Choice of porcine model: posterior fossa
bony anatomy and anatomical relationships of the posterior porcine skull base are analogous to human basicranium

8. Animal Experimental Models
Endoscopic cranial nerve vascular decompression:
aim
develop animal model for endoscopic surgery of the posterior fossa

9. Animal Experimental Models
Endoscopic cranial nerve vascular decompression:
relevance
improved surgical therapy for cranial nerve compression syndromes
trigeminal neuralgia (CN V)
hemifacial spasm (CN VII)
intractable vertigo (CN VIII)
glossopharyngeal neuralgia (CN IX)
spasmodic torticollis (CN XI)

10. Animal Experimental Models
Endoscopic cranial nerve vascular decompression:
method
30 kg Hampshire-Yorkshire-Duroc swine
general anesthesia
left lateral decubitus position
2 cm retrosigmoid craniotomy
endoscopic exploration of posterior fossa
identification of cranial nerves

11. Animal Experimental Models
Endoscopic cranial nerve vascular decompression:
results
visualization of cerebellum, lower cranial nerves (CN IX-XI), acousticofacial bundle (CN VII-VIII), and trigeminal nerve (CN V)
panoramic views with addition of angled endoscopes
impediments to visualization (e.g., petrous apex) circumnavigated

12. Animal Experimental Models
Endoscopic cranial nerve vascular decompression:
conclusion
“The dynamic optical qualities of the endoscope should allow for more careful navigation through the very constrained cavities of the skull base, for more detailed appreciation of critical surgical anatomy, and for more thorough surgical intervention with fewer complications due to better visualization.”
Jarrahy R, Young J, Berci G, Shahinian HK. Endoscopic skull base surgery II:
a new animal model for surgery of the posterior fossa. J Invest Surg 1999;13:1-6.

13. Clinical Trials: Endoscopic Posterior Fossa Surgery
Aim
determine the efficacy of endoscopy as an imaging modality in posterior fossa microvascular decompression

14. Clinical Trials: Endoscopic Posterior Fossa Surgery
Design
case series (n = 210) with retrospective review of medical records and operative video

15. Clinical Trials: Endoscopic Posterior Fossa Surgery
Intervention
microvascular decompression via retrosigmoid craniotomy (traditional approach)
preliminary endoscopic survey of nerve-vessel conflicts prior to microscopic intervention
final endoscopic survey to assess adequacy of microscopic therapy

16. Clinical Trials: Endoscopic Posterior Fossa Surgery
Results
251 total nerve vessel conflicts
27% not detected by microscopy--endoscope needed to diagnose and treat these conflicts

17. Clinical Trials: Endoscopic Posterior Fossa Surgery
Results
in 24% of patients, final endoscopic survey revealed incomplete decompression following microscopic therapy

18. Clinical Trials: Endoscopic Posterior Fossa Surgery
Conclusion
“In this series microscopic exploration of the surgical field failed to detect roughly one-quarter of the offending vessels. Likewise…, in one-quarter of cases what was deemed to be an adequate decompression of the trigeminal nerve under the microscope proved to be incomplete. These observations emphasize the value of controlled application of endoscopic techniques at the cerebellopontine angle and merit further attention.”
Jarrahy R, Berci G, Shahinian HK. Endoscope-assisted microvascular decompression
of the trigeminal nerve. Otolaryngol Head Neck Surg. Accepted for publication.

19. Animal Experimental Models
Choice of porcine model: anterior fossa
bony anatomy and anatomical relationships of the anterior porcine skull base are analogous to human basicranium

20. Animal Experimental Models
Endoscopic pituitary surgery:
aim
develop animal model for pituitary surgery/endoscopic surgery of the anterior fossa
eliminate invasive techniques associated with traditional approach
nasal/septal complications
upper labial hypoesthesia
postoperative nasal packing

21. Animal Experimental Models
Endoscopic pituitary surgery:
relevance
improved surgical therapy resection of pituitary tumors, tumors of the anterior fossa
chordoma
meningioma
craniopharyngioma
teratoma
other tumors

22. Animal Experimental Models
Endoscopic pituitary surgery:
method
30 kg Hampshire-Yorkshire-Duroc swine
general anesthesia
supine position
gross dissection of hard palate
endoscopic exploration of sella turcica, parasellar and suprasellar areas

23. Animal Experimental Models
Endoscopic pituitary surgery:
results
clear visualization of pituitary gland, hypophyseal stalk, cavernous sinuses, optic nerves
angled endoscopes enabled visualization of lateral recesses (cavernous sinuses) and suprasellar areas

24. Animal Experimental Models
Endoscopic pituitary surgery:
conclusion
“Our results highlight the usefulness of endoscopy in providing superior exposure of the structures that are critical to hypophysectomy.”
Jarrahy R, Young J, Berci G, Shahinian HK. Endoscopic skull base surgery I:
a new animal model for surgery of the posterior fossa. J Invest Surg 1999;12:1-5.

25. Clinical Trials: Endoscopic Pituitary Surgery
Aim
objectively demonstrate that the use of endoscopy in pituitary surgery improves visualization and surgical outcome

26. Clinical Trials: Endoscopic Pituitary Surgery
Design
case series (n = 229) with retrospective review of medical records and operative videotape

27. Clinical Trials: Endoscopic Pituitary Surgery
Intervention
transseptal transsphenoidal approach to the sella turcica (traditional microscopic technique)
final endoscopic survey of sella and parasellar areas following completion of microscopic resection
residual tumor fragments--precursors to recurrence and persistent endocrinological symptoms--noted and resected

28. Clinical Trials: Endoscopic Pituitary Surgery
Results
residual tumor noted in 33% of patients (43% of macroadenomas) following what was thought to be complete resection via the microscope
angled endoscopes were able to expose lateral recesses of sella turcica where these fragments were missed

29. Clinical Trials: Endoscopic Pituitary Surgery
Conclusion
“…these observations do provide evidence that endoscopic imaging of the intrasellar, parasellar, and suprasellar spaces is more comprehensive than that provided by the operative microscope… [T]he potential impact upon the efficacy of tumor resection and subsequent rates of tumor recurrence is significant when endoscopy is implemented as an imaging modality in the surgical management of pituitary tumors.
Jarrahy R, Berci G, Shahinian HK. Assessment of the efficacy of endoscopy in the resection
of pituitary adenomas. Accepted for publication in Arch Otolaryngol Head Neck Surg.