This is another area of special interest in Neurological Surgery
which utilizes highly refined microsurgical dissection and
manipulation techniques that are primarily used to address blood
vessel problems inside the Skull, Spinal Column, Brain and /or
Special skills are required to utilize these techniques.
In all of these instances, the Neurosurgeon is using a
sophisticated Neurosurgical Operating Microscope to magnify vision,
as well as delicate instruments designed specifically for this type
Microvascular Neurosurgical Operations that address blood vessel
problems include those that are conducted for:
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- Microvascular Decompression Operations (MVD)
as well as
In these conditions, cerebral arteries and/or their branches
impinge upon one or more of the specialized Cranial Nerves that enter
or emerge from the Brain Stem. As they beat synchronously with the
heart, they tend to wear out a portion of the insulating material
(Myelin) of these nerves resulting in a "short circuit" and the symptoms
of each of these afflictions. Using
Microvascular Decompression (MVD)
Techniques the Neurosurgeon is able to reposition the offending
vessel while placing some form of permanent padding to retain the
vessel in a new and transposed position relative to its previous
Figure 1: Operative Photo Left Retromastoid "Keyhole"
Craniectomy for Trigeminal Neuralgia.|
Superior Cerebellar Artery (Upper Slender Arrows)
Compare the Artery to Figure 2 below.
The Left Trigeminal Nerve root entry Zone (Lower Broad Arrow)
is compressed by a tortuous and redundant Superior Cerebellar
Figure 2: Operative Photo Microvascular decompression (MVD)
of the Left Trigeminal Nerve (Same patient as Figure 1).|
The Superior Cerebellar Artery (Upper Left Arrow) has been
transposed and held in the new position by a permanently
implanted Ivalon sponge (Lower Left Arrow).
- Skull Base Tumors
Skull Base Tumors are
tumors that involve the bone in the region of the Base of the Skull
and often have an intimate relationship with delicate and vital
structures (Cranial Nerves, Cerebral Arteries and Veins) which must be
preserved both anatomically and functionally in order to
have a fully satisfactory outcome. The Microvascular Neurosurgeon's
special dissection techniques are often invaluable when addressing
these difficult circumstances.
Figure 3A (Left): MRI Scan (Sagittal View-Gadolinium enhanced) of
a large Anterior Cranial Fossa SKULL BASE TUMOR that extends into
the Posterior Cranial Fossa and involves multiple vital arteries
at the Skull Base.|
Figure 3B (Right): MRI Scan (Coronal View) of the same patient. The
tumor involves both Frontal Lobes of the Brain and both Orbits as
well as major vessels such as both Anterior Cerebral and Internal
Carotid Arteries and their branches.
Microvascular dissection principles and techniques reduce the risk
of injury to the vital structures in this area.
- Intracranial Arterial Reconstruction
Microvascular techniques are utilized in order to prevent
Strokes from occurring in patients with certain types of
Obstructive Cerebrovascular conditions that do not respond to
other therapies. Examples of this include extensive multivessel
atherosclerosis (hardening of the arteries) that results in
decreased blood supply to the Brain. An example of this is
Extracranial to Intracranial Arterial Bypass Grafting as illustrated
in Figures 5 through 8.
These operations are referred to as Cerebral Revascularization
(or Extracranial-Intracranial [EC-IC] Bypass Graft). Patients
requiring the reconstruction of the arterial blood supply to their Brain
(either to deal with an obstructive blood vessel problem that
would lead to Stroke, or where tumor removal requires the sacrifice
of a major cerebral artery) will understand the requirement
to have a Neurosurgeon with special skills, knowledge and expertise
to undertake this extremely delicate task.
Several techniques are available including the repair and or bypass
of larger vessels such as the Intracranial Internal Carotid Artery
as well as bypass of somewhat smaller caliber arteries such as the
Middle Cerebral Artery. Figures 5, 6 & 7 concern a "large" vessel
bypass graft using a vein graft technique to create a "new" Carotid
Artery. Figures 8 A & B concern the creation of a smaller vessel
bypass graft using a scalp artery (the Superficial Temporal Artery)
to supply the Brain's Middle Cerebral Artery blood requirements.
Figure 5: Diagram of Extracranial to Intracranial Carotid Artery Bypass Graft.|
This technique is used to bypass a major obstruction in the
Carotid Artery where conventional treatments are not appropriate.
A vein, harvested from the patient's leg, is inserted between the Carotid
Artery in the neck (Arrow) and passed under the skin to enter the skull
cavity where it is sutured to the Intracranial Carotid Artery.
NOTE: The concepts and techniques described in this section were
initially elaborated in: "Microsurgical Cerebral Revascularization:
Concepts and Practice. Surgical Neurology 1:355-359, 1973. (Lazar,
M.L., and Clark, W.K.)
Figure 6: Post-operative Cerebral Angiogram of an Extracranial
to Intracranial (EC-IC) Carotid Artery Bypass Graft.|
A vein graft (Broad Arrow) has been sutured in place from the
Right Common Carotid Artery in the neck and brought in through a
Craniotomy and sewn to the Intracranial Carotid Artery. This "new"
vessel" now supplies the ENTIRE Right and Left Anterior & Middle
Cerebral Artery distribution.
This patient had a high grade obstruction of his Left Carotid
Artery at the Carotid Siphon with Complete Occlusion of his
EXTRACRANIAL Right Carotid Artery. Post-operatively the patient
was found to have experienced an ASSYMPTOMATIC complete occlusion
of the Left Carotid Artery with the "new" Bypass Graft supplying
the Anterior and Middle Cerebral Arterial Circulation to BOTH
Cerebral Hemispheres (Small Arrows.)
Figure 7: Post-operative Cerebral Angiogram (Lateral View- Same Patient as Figure 6)|
The vein graft extends from the Extracranial Carotid to
the Intracranial carotid Artery (Arrows)
Figure 8A (Left): Pre-operative Left Carotid Angiogram. The entire
Left Middle Cerebral Artery (MCA) circulation (Arrow) is absent
secondary to MCA occlusion.|
Figure 8B (Right): Left Common Carotid Artery Angiogram. Post-operative
EC-IC Bypass Graft (Superficial Temporal Artery to Middle Cerebral
Artery). The entire MCA distribution is now supplied by the
This EC-IC Bypass involved suturing a 2 millimeter Superficial Temporal
Artery to a 1 millimeter MCA Cortical Arterial Branch.
- Aneurysms & Arteriovenous Malformations
Exquisite Microvascular dissection techniques are required when
surgically confronting Intracranial vascular problems such as
The majority of these aneurysms are located around the "base" of the
Brain. As such they may have intimate relationships with other vital
structures such as Cranial Nerves, adjacent major Cerebral Arteries
and Veins as well as Brain structures. The Microvascular dissection
techniques are useful in preserving these structures and their function
while eradicating the threat to life that the aneurysm represents.
Figure 9A (Left): Left Carotid Angiogram (Lateral View). Left Internal
Carotid Artery Aneurysm (Arrow)|
Figure 9B (Right): Left Carotid Angiogram (Anterior-Posterior
Oblique View) Left Carotid Artery Aneurysm (Arrow)
Figure 10A (Left): Operative Photo. Left Internal Carotid
Artery Aneurysm (Slender Arrows) arises from the Left Internal
Carotid Artery (Broad Arrow) (Note: The Left Optic Nerve is just
to the RIGHT of the Carotid artery and is partially obscured by
the Arrow in each photo.)|
Figure 10B (Right): Operative Photo. The Aneurysm has been
successfully obliterated by placing an aneurysm clip around the "neck"
(Slender Arrow) to stop any blood from flowing to the aneurysm while
maintaining the patency of its parent Left Carotid Artery Broad Arrow).
Figure 11: Left Carotid Angiogram (Lateral View)|
Left Posterior Frontal AVM demonstrates the tangle of vessels
that make up the AVM.
Enlarged arteries "feed" the AVM (Left Arrows) and enlarged Veins
"drain" the AVM (Top Arrow)
Figure 12: Operative Photo. After Microvascular Resection|
Part of the challenge of this surgery is to remove the AVM while
preserving normal adjacent Brain and the vital vessels that
supply the Brain.
For the most part the AVM does not incorporate functioning Brain;
however, it is intimately and intricately involved with the
contiguous Brain elements.
A "cavity" is left where the AVM previously resided.
- Spinal Cord Arteriovenous Malformations (AVM) & Spinal Cord Tumors
These same delicate techniques Microvascular dissection techniques and surgical
principles are required for
Intraspinal Vascular problems and
Spinal Cord Tumors.
Figure 13: Operative Photo of Spinal Cord Arteriovenous Malformation.|
The "feeding artery" (Upper Arrow) supplies the tangle of vessels
that comprise the Arteriovenous Malformation-AVM- (Bottom Arrow)
The AVM obscures the Spinal Cord from view. A portion of the
Spinal Cord (white tissue-Middle Arrow) is visible.
Figure 14: Operative Photo of Intradural Spinal tumor (Middle Arrow).|
Compressed Intradural Spinal Nerves have been displaced by the tumor
(Upper & Lower Arrows).
Figure 15: Operative Photo (Same patient as Figure 14.) The
Intradural Spinal Tumor has been completely removed (using Minimally
Invasive Microvascular Dissection techniques) with preservation of
the Spinal Nerves and their blood supply.|
- Deep-seated Brain Tumors
Microvascular dissection techniques are often used for surgical
procedures that address pathological conditions in very confined areas
such as Tumors located deep within the Ventricles of the Brain, Tumors
within and around the Brain Stem and Tumors within the
Orbit of the Skull.
Figure 16A (Left): MRI Scan (Transaxial View). A deep-seated Tumor
(Arrow) fills the posterior aspect of the Third Ventricle.|
Figure 16B (Right): MRI Scan (Sagittal View-Gadolinium Enhanced).
The tumor (Left Arrow) has an intimate relationship with vital
vascular structures including the Vein of Galen (Right Arrow)
and its branches (Top Arrow).
Figure 17: Operative Photo|
A 3rd Ventricular Tumor has been approached through a Right Occipital
Craniotomy (in a direction indicated by the "Right Arrow" in
Figure 16B above).
The Vein of Galen (Lower Arrow) has been carefully dissected allowing
access to the Tumor that filled the 3rd Ventricle (Top
- Optic Nerve & Orbital Tumors
Microvascular dissection techniques are often required when dealing
with the delicate structures within the Orbit of the Skull.
Tumors of the Optic Nerve
or those that are directly adjacent to the Nerve and Globe
require very delicate management in order to preserve useful vision.
(An example of this is illustrated in the case of an Optic Nerve Meningioma
in Figures 18 A & B.)
Figure 18A (Left): CT Scan ("Dye-Enhanced" Transaxial View of
Orbits). A Right Optic Nerve Meningioma widens the appearance of
the Optic Nerve (Arrow)|
Figure 18B (Right): Operative Photo of this Right Optic Nerve
Meningioma AFTER MOST OF THE TUMOR HAS BEEN REMOVED.
The Meningioma had partially encircled the Nerve. It is a
daunting technical task to preserve the tiny Optic Nerve vessels
while removing the tumor. Remnants of tumor (Arrows) remain in this
photo and must be removed in order to prevent a recurrence. A COMPLETE
REMOVAL WITH PRESERVATION OF VISION WAS ACCOMPLISHED.
This page last edited on 2/22