history, working, optics and salient features of operating microscopes in neurosurgery and endoscope. role of endoscopes in various surgeries and newer prospects of both microscopes and endoscopes

1. Microscopes and Endoscopes
in Neurosurgery
Presented by:-
Dr Rahul Jain
SR-2 Neurosurgery
Moderated By:-
Dr V. C. Jha
Dr Nitish Kumar
Dr Gaurav Verma

2. THE OPERATING MICROSCOPE

3. History
• The first described use of a microscope within the
operative theatre was in 1686 by Giuseppe Campani,
who used a compound microscope to examine wounds
and scar tissue.
• The use of magnification in surgery began in earnest in
the second half of the 19th century with the
development of loupe spectacles.
• Surgical binocular microscope first used by Carl Nylen in
1929 for middle ear surgery.
• In 1957, Theodore Kurze became the first neurosurgeon
to use the microscope in removal of a neurilemmoma
of the seventh nerve from a 5 year old boy.

4. • In 1958, R.M.P. Donaghy established the first
microneurosurgical training laboratory where
several neurosurgeons like M Gazi Yasargil also
trained.
• Yasargil made several revolutionary improvements
in the design of the operating microscope and is
regarded as the “Father Of Microneurosurgery” for
his contributions.
• Julius H. Jacobson wanted to allow a second
surgeon to assist him while using magnification aids
during the surgery. Jacobson contacted Carl Zeiss,
Inc., and in 1964, Dr. Littman designed a
microscope for Jacobson by adapting beam-splitter
technology. This microscope was named the
“Diploscope”

6. Optical principles
1. Magnification
• dependent on the magnification of the objective and
eyepiece
• a zoom system of lenses is interposed between these
two principal lenses allowing continuous change in
magnification
2. The field of view changes with the magnification
according to the formula
Diameter of field = 200/total magnification

7. 3. Depth of field is also an important parameter which is a
measure of field of vision in a stereoscopic system.
The depth of field
• increases with the square of the focal length of the
objective lens
• decreases linearly with the magnification of the
microscope.
4. Working distance of a surgical microscope gives
a surgeon space to handle surgical instruments.
The working distance of the first monocular
microscope was 60 mm, and the first binocular
microscope had a working distance of 75 mm.
Zeiss OPMI 1 came out in 1953 and had a
working distance of 100 to 405 mm. Since then,
working distance has been improving to meet
the need of different types of surgeries varying
from 200 to 500 mm.

9. Components
• surgical microscope can be roughly divided into a
microscope body, a light source, and a supporting
structure.
• The microscope body has all the high-precision
optics that provide a clear magnified image with
the minimum distortion
• The binoculars mounted on the microscope head
offer stereopsis.
• Multiple optical ports are open for adaptation of
imaging devices such as video cameras or for
assistants to share the identical FOV.

10. • The light source is installed away from the
microscope to avoid heating the microscope optics
or the surgical site.
• Based on the configuration, there are four types of
surgical microscopes: (i) on casters, (ii) wall
mounted, (iii) table top, and (iv) ceiling mounted.
• The on-caster stand is the most popular supporting
structure due to its better mobility, but a ceiling
mount or wall mount can help with space
management.

11. A. Optical System
• main determinant of the imaging quality that a system
can achieve
• Basically a binocular (with eyepieces on top) with a
close-up lens, namely the optical components including
the objective lens and the magnification changer (or
zoom changer).
• Total magnification (Mtotal) of a surgical microscope is
determined by all the four optical components in the
microscope, namely the focal length of the objective
lens (FOBJ), zoom value (MZOOM), the focal length of
binocular (FTUBE), and the magnifying power of
eyepieces (MEP)

12. • Resolution measures the acuity improved by
magnification. It is the ability of an optical system to
distinguish two separate entities. Human eyes have an
inherent resolution of 0.2 mmbut
with 20× magnification, it can be increased to 0.01 mm.
• The design of optics is vital to the image quality of a
surgical microscope. Aberration is an inherent property
of optical systems, and it causes the blur or distortion
of images, which is adverse to the desire for a clear
view
• Apochromatic lens – developed by Ernst Abbe, a
physicist hired by Carl Zeiss, not only corrects for two
wavelengths (red and blue) to reduce spherical
aberration but also utilizes the exceptional quality
optical materials that have unusual and desirable
characteristics to reduce chromatic aberration for three
wavelengths (red, green, and blue).

13. • Focusing is essential for a clear view. Depends on
many factors such as quality of optical design, the
size of objective lens aperture, magnification of the
object, and it is reciprocal of the resolution.
• Parfocal, which means an optical system can stay in
focus even with magnification changes.

14. B. Illumination System
• The original illuminator in the
earliest surgical microscopes was
an independent bulb externally
mounted on the side of the
microscope.
• Modern microscopes have
adopted high-power light sources
with stable light intensity and
close-to-sunlight color
temperature.
• With the built-in coaxial
illuminator, light is rerouted to the
viewing axis and projected down
through the objective lens.

15. • LED can provide illumination in the visible
wavelength range with good brightness, good
stability, longer life, less power consumption, and
extremely low heat; disadvantages: the higher
color temperature and narrower wavelength range
make the light not as close to sunlight; its spectrum
is insufficient for fluorescence-guided applications
especially ICG imaging.
• Automatic adjustment of light collimation in
modern microscopes allows appropriate
illumination as the magnification is varied.
• Auxiliary illumination In some advanced models
auxiliary illumination is being used to decrease
shadowing when changing the viewing angle.

16. • In some contemporary surgical
microscopes, small angle
illumination (SAI), provides a
concentrated and evenly
distributed light beam, a bright
view, and an improved depth
perception, the shadow that
appears at the edge of the
viewing field is significantly
reduced. Light management-
irradiance (irradiation
of a surface, W/m2) of
a microscope light
source increases with
decreasing spot size
and decreasing working
distance.

17. C. Mechanical System and
Automation
• Mechanical stability is the second most important
criterion in selecting a surgical microscope.
• The drift or vibrating of a microscope after positioning
distracts surgeons’ focus on the surgical site.
• Microscope draping is a necessary requirement for
sterilization in the OR.
• Modern surgical microscopes have made it an easy and
time-saving process to balance. All six axes can get fully
balanced with two pushes of a button, and
intraoperative rebalance can be quickly and accurately
accomplished with a single push of button on handgrip.

18. • Robotic visualization system, two robotic positioning features,
namely “point lock” and “position memory”
• With “point lock,” the microscope head stays in focus when
being manually or automatically moved during surgery,
“Position memory” makes the system able to “bookmark”
positions and transit quickly and smoothly back to these
positions with no need to rediscover.
• Ergonomics guarantees a comfortable and flexible working
position; maneuverability is valued for the simplification of
microscope operations.

19. D. Visualization System
• Microscope head usually has one main observation
port and one rear or lateral port for co-observers.
• Stereopsis is a key feature of binocular surgical
microscopes. The depth information can aid the
detection of diagnostically relevant shapes,
orientations, and positions of anatomical features,
especially when monocular cues are absent or
unreliable.
• A screen can show not only the white-light image of
the surgical site but also other images, such as
intraoperative OCT images, for surgical guidance.

20. • The images can
be shown
separately,
overlaid on the
white-light
image,or even in
picture-in-
picture
endoscopic
assistance view
for endoscopic
microinspection
tools.

21. Application of microscope in
neurosurgery
• Role of microscope in improving surgical outcomes
first demonstrated in Acoustic Neuromas.
• Now routinely used in almost all intradural
operative procedures whether in the brain or spine.
• Its use has resulted in smaller wounds, less
postoperative neural and vascular damage, better
hemostasis, more accurate nerve and vessel
repairs, and surgical treatment of some previously
inoperable lesions

22. It has improved operative results by
• permitting neural and vascular structures to be
delineated with greater visual accuracy
• deep areas to be reached with less brain retraction
and smaller cortical incisions
• bleeding points to be coagulated with less damage
to adjacent neural structures,
• nerves distorted by tumor to be preserved with
greater frequency
• enabling anastomosis and suturing of small vessels
and nerves not previously possible to be
performed.

23. Endoscopes

24. Neuroendoscopy
• Introduction of endoscope was undoubtedly a
great advancement in neurosurgery.
• It minimises trauma to the brain tissue and
maximises the vision around the remote areas.
• The access to the ventricle and cisterns has become
much easier.
• Development in optics, lenses, long and angled
instruments made the endoscopy in neurosurgery
very versatile.

25. History

26. • early 1970s, both flexible fibreoptic and high-
resolution rigid endoscopes.
• At the initial days of neuroendoscopy, as ventricles
contain the ideal medium of crystal-clear CSF, the
endoscopic procedures were confined to those.
• Currently, the field of neuroendoscopy has
extended beyond ventricular procedures and is
currently applied for all types of neurosurgically
treatable diseases such as intracranial cysts,
intraventricular tumors, hypothalamic hamartoma
(HH), skull base tumors, craniosynostosis,
degenerative spine disease, and rare subtypes of
hydrocephalus.

27. Equipment
• include: video camera,
camera control units,
light source, video
recorder, video monitor
and a computerized
system for storage of
video segments or
single-picture capture
• With the fixation arms,
sudden movement of
the hand or hand
tremor can be
minimized.

28. instruments include a pair
of grabbing forceps and
scissors, a monopolar or
bipolar coagulation device,
an irrigation system, and a
straight and one or more
scopes with various angles.
Straight and
angled scopes
Light source
Endoscopic
microsurgery
instruments
Flexible endoscope

29. • Frameless computerized neuronavigation has been
used more in intracranial endoscopic neurosurgery
to increase the accuracy and precision.
• Modern three-chip technology provides impressive
color depth and brilliant red differentiation.
• The latest Full HD technology delivers lag-free
images even with rapid camera movements.
• improved maneuverability of the scope by
reduction of the bulk and integration of the camera
and fiberoptic light components with an extensive
viewing angle from 0 to 70 degrees, along with the
provision of maintaining surgical orientation.

30. Endoscopic third ventriculostomy

31. Endoscope-assisted microsurgery
• most rapidly growing area in
endoscopic neurosurgery.
• allows the neurosurgeon to view
tumor remnants such as those
hidden behind eloquent brain
tissue, a cranial nerve, or the
tentorial edge.
• Rigid endoscopes with various
angles and flexible endoscopes help
the surgeon to look around the
remote corners which can be very
useful in the removal of tumors and
the clipping of cerebral aneurysms.

32. • Endoscopes are increasingly used to inspect
tumors, tumor beds following resection, aneurysms
and other pathologies.
• Risks - the most problematic of which of using the
scope is the risk of friction upon structures while
introducing the scope.
• If the scope is not fixed, then small, barely
noticeable movements at the tip can be the result
of larger excursions at the back of the scope.

33. Endoscopy for skull base lesions
• Pioneering work of neuroendoscopy for skull base
tumors was done by Carrau and colleagues in 1996,
who reported their original experience of
endonasal transsphenoidal hypophysectomy at the
University of Pittsburgh.
• The endoscopic approach was expanded by de
Divitiis and colleagues to include other lesions of
the sellar and parasellar regions in their study in
2002.

34. • The bilateral endonasal
endoscopic approach now
allows for visualization of
tumors at the anterior skull
base up to the crista galli and
down to the level of C2
• Application - pituitary
adenoma and
craniopharyngioma
• Supradiaphragmatic lesions
can be removed via the
endonasal route
• suprasellar prechiasmatic preinfundibular lesions can be
removed with the transtuberculum-transplanum sphenoidale
approach

35. Endoscopic application in
aneurysm surgery
• Endoscope can be used in and around the
operative field of aneurysms easier and safer.
• Furthermore, the endoscope facilitates
confirmation of optimal clip positions.
• Chowdhury et al. in 2012, the variations were
identified and the authors concluded endonasal
extended transsphenoidal approach can fully
expose CW with brain in situ to observe the circle
for variations and asymmetry.

36. • Taniguchi et al. in 1999, reported in their series of 54
cases, the endoscope was used for further clarification
of the detailed additional anatomy in 9 cases (16.7%).
The surgeons reapplied the clip on the basis of
endoscopic information which was gained after the
initial clipping in 5 cases (9.3%).
• In general, very large and giant aneurysms gain fewer
benefits from the endoscope than smaller ones in the
same location, because the mass of the lesion
compromises insertion and fixation of the endoscope in
the operative field.
• The endoscope is especially useful in the treatment of
deeply located cerebral aneurysm. The effectiveness of
the endoscope is limited for superficially located
aneurysms like middle cerebral artery aneurysms and
distal aneurysms such as pericallosal aneurysms

37. Microvascular decompression
• Endoscopic techniques such as endoscopic or
endoscope-assisted MVD (EMVD) have been used
for MVD operations.
• Though many neurosurgeons do not find EMVD is
superior to MMVD as the access for MMVD can be
small and the offending vessels can be separated
easily through that.
• several authors indicated the superior efficacy of
endoscopic or endoscope assisted surgery in
locating the offending site of neurovascular conflict
when compared with the microscopic surgery

38. • Regarding TN, SCA usually runs medial to the trigeminal
nerve and the nerve can be compressed in a rostromedial
direction.
• An approach with the thirty degree endoscope through
the lateral tentorial surface of the cerebellum via a
keyhole provides excellent exposure of the trigeminal
nerve from the REZ to the Meckel’s cave.
• For HFS, the REZ of the facial nerve is located
immediately medial to cranial nerve VIII in the
supraolivary fossette, often compressed by the AICA from
a caudal direction.
• 300 or 450 view of endoscopes through the petrosal
surface of the cerebellum via a retrosigmoid keyhole
clearly demonstrates the neurovascular structures, AICA
can be transposed caudally and fixed at the petrosal dura
mater.

39. • In the meta-analysis by Li et al., it is shown that,
EMVD was superior considering the perioperative
safety as with less perioperative complications.
• Facial paralysis was significantly low in EMVD, and
CSF leak and dysaudia (defective articulation
stemming from auditory disability) also showed a
similar trend with the previous discussions.

40. Evacuation of ICH: endoscopic and
endoscope-assisted
• Endoscope-Assisted Evacuation describes the
creation of a small craniotomy or craniectomy with
stereotactic introduction of a port or sheath to the
hematoma.
• It is followed by evacuation with the endoscope
and a suction device or a combination device
where the suction device is there side by side in the
lumen of the sheath which is even less traumatic.
• Endoscopic evacuation is one of the earliest studies
to investigate active MIS ICH evacuation using only
endoscopes.

41. Newer prospects
1. Intraoperative
flourescence
• It is an upcoming
technique available in
several advanced
micrscopes.
• applicable in aneurysm
and tumour surgery
where it allows the
visualisation of sub
millimeter vessels by the
use of Indo-cyanin green
dye used as fluorescing
agent.

42. • The detection module (blue) and the illumination model (yellow)
are attached to the Zeiss Pentero OPMI head and can be used
without affecting the standard operation of the microscope

43. 2. Augmented Reality
• AR is an immersive environment that contains real
and computer-generated elements.
• AR can be very helpful with preoperative planning
and intraoperative surgical navigation.
• It provides the visualization of anatomical
structures beneath human skin intraoperatively by
overlaying segmented preoperative images to the
corresponding area on the human body.
• There are three core components of AR. First one is
a virtual image or environment, which refers to the
computer-generated 3D reconstruction. other two
are the registration of the virtual environment with
real space, and the display technology to combine
the virtual and real environment, respectively.

44. 3. Laser Speckle Contrast Imaging
• for real-time assessment of perfusion.
• backscattered light from a scattering medium that is
illuminated by coherent light forms a random
interference pattern, namely the speckle pattern.
• When illuminating tissue with a coherent laser and
acquiring images of the tissue with adequate exposure
time, the movement of red blood cells can cause
fluctuation in speckle patterns, thus the blurring of the
images can be related to the blood flow.
• This blurring of the recorded pattern is used to calculate
the speckle contrast, which is useful for the quantitative
analysis of blood flow.
• fast and full-field, providing a 2D perfusion map without
scanning.

45. SurgeON System has imaging specifications
that are suitable for neurosurgery
Comparing LSCI with ICG video angiography, this study demonstrated
that the dye-free LSCI could not only provide more information such
as the CBF variation but also guide the surgery in real-time.

46. Conclusion
• In conclusion, the surgical microscope and
endoscope are powerful tools that can offer
optional magnifications, bright illumination, and
clear visualization.
• used in different types of surgeries and has
improved surgical outcomes as well as surgeons’
ergonomics. It is anticipated that the integration of
surgical microscopes and endoscopes with state-of-
the-art optical imaging technologies will change the
clinical practice in the operating room and benefit
patients

47. References
1. Youman and winns neurological surgery 8th ed
2. Ali Kawsar K. Endoscopy in Neurosurgery [Internet].
Frontiers in Clinical Neurosurgery. IntechOpen; 2021
3. Uluç, K., Kujoth, G. C., & Başkaya, M. K. (2009).
Operating microscopes: past, present, and
future. Neurosurgical Focus FOC, 27(3), E4
4. Ling Ma and Baowei Fei.Comprehensive review of
surgical microscopes: technology development and
medical applications. J Biomed Opt. 2021 Jan; 26(1):
010901
5. Luigi Rigante et al. Cleveland Clinic Journal of
Medicine October 2019, 86 (10) 16ME-24ME
6. Carl zeiss kinevo 900 brochure