Sheng, Gee Teak
(2011)
Endonasal endoscopic cadaveric
dissection of sellar-suprasellar
region and cavernous sinus -
a descriptive and morphometric study.
Masters thesis, Universiti Sains Malaysia.
Abstract
Endoscopic skull base surgery has evolved in recent years from technological
advancement in medical equipment related especially to the field of optical
technology. The paradigm shift that occurred with the introduction of the modem rigid
rod lens endoscope into the neurosurgical armamentarium saw the exponential
expansion of the role of its use in pituitary tumor and endonasal skull base surgery.
Due to the distinct differences between microscope and endoscope optic principles,
it is important that familiarity with endonasal endoscopic anatomical landmarks be
recognized by the young trainee surgeon in neurosurgery. A morphometric study of
the relevant anatomy of endonasal approaches to the sellar and parasellar region is
crucial to gain understanding of the anatomy of this region.
Three asian human cadaveric heads underwent staged endonasal endoscopic
dissections and anatomical landmark images were captured and morphometric
measurements were attempted. Twenty Paranasal Sinus Protocol Computer
Tomography of patients undergoing studies for suspected sinus disease and 20
Pituitary protocol Magnetic Resonance Imaging studies of patients being
investigated for suspected pituitary diseases were selected for morphometric
measurements. On the Paranasal Sinus Protocol Computer Tomography, the
coronal surface area of middle and inferior chonchal bone, the whole turbinate and the meatus were measured using Osirix software. On the coronal CT imaging the
vidian canal- foramen rotundum distance were measured with Osirix software. On
the Pituitary MRI the maximal anterior sphenoidal width, naso-vomer distance,
chiasmal width and height, infundibulum distance, inter-carotid distance, sphenoid
septum numbers, position, height and projection towards paraclival and parasellar
ICA prominence, suprasellar cistern volume, pituitary area and computed volume
were measured with Osirix software. On staged endonasal endoscopic cadaveric dissections; the middle turbinate,
posterior choana and the sphenoid ostium were identified during the nasal and
sphenoid phase. Identification of sella floor with adjacent clivus, optic and carotid
protuberances and the optico-carotid recesses were documented during the sellar
phase. The suprasellar and parasellar phase, the arteries identifiable were the ICA,
ACA, MCA, PCom, basilar artery, PCA, superior cerebellar, and AICA. The cranial
nerves Ill, IV, V and VI were identified. The pituitary gland with its stalk, posterior in
relation to the optic chiasm was noted. Mamillary bodies and anterior floor of third
ventricle were identified and opening was made in its floor to gain access into the
third ventricle. The foramen of Monroe with its choroid plexus, the massa intermedia,
and the superior medullary velum could be visualized with the 3 mm endoscope for
intraventricular exploration. On the paranasal sinus CT images, the inferior chonchal mean area at anterior,
middle and posterior coronal levels were 0.13, 0.24 and 0.14 cm2 on the left side and 0.15, 0.27 and 0.16 cm2 on the right side. The whole inferior turbinate mean area at
anterior, middle and posterior coronal level were 1.10, 1.39 and 1.19 cm2 on left side
and 1.02, 1.36 and 1.14 cm2 on right side. Majority of inferior meatus area on all
levels and both sides were more than 0.20 cm2
• The inferior meatus area is smallest
at its anterior coronal level (mean of 0.38 cm2 on both side) and widest at the mid
coronal level (right 0.79 cm2 and left 0.75 cm2).
The mean middle chonchal area at vertical, oblique and horizontal coronal levels
were 0.19, 0.12 and 0.20 cm2 on the left side and 0.21, 0. 14 and 0.14 cm2 on the
right side. The mean of whole middle turbinate area at vertical, oblique and
horizontal coronal levels were 0.52, 0.41 and 0.47 cm2 on the left side and 0.55, 0.46
and 0.49 cm2 on the right side. Majority of the middle meatus studied demonstrated
a surface area of more than 0.20 cm2 and none of the concha, whole turbinate and
meatus areas was significantly different when comparison were made for gender
group as well as among the age groups. The mean vidian canal-foramen rotundum
distance was 5.5 mm on right side and 5.3 mm on left side.
On the Pituitary protocol MRI, the mean maximal anterior sphenoidal width was 2.92
cm, naso-vomer distance 3.98 cm, chiasma width 1.48 cm, chiasma height 0.21 cm,
infundibular height 0.61 cm, inter-carotid distance 1.69 cm, right, middle and left
sphenoid septum heights were 1.31, 1. 7 4, 1.27 cm respectively. Computed
suprasellar cistern and pituitary volume were 1.83 and 0.44 cm3 respectively. Forty-five percent of sphenoid septums were in close proximity to the ICA
prominence, with 75% of right sphenoid septum and 64% of left sphenoid septum
pointed towards the ICA prominence. Understanding the endonasal endoscopic anatomy of the sellar, suprasellar and
cavernous sinus region augmented by morphometric measurements of relevant
landmarks is important to improve the accuracy of the endonasal endoscopic
trajectory to the midline and extended transsphenoidal approaches and this would
translates into a 'safe road map' during surgery.
Actions (login required)
 |
View Item |
