Diagnostic value of preoperative Magnetic Resonance Imaging in evaluation of vascular compression of trigeminal nerve in patients with trigeminal neuralgia
Neurovascular compression of the trigeminal nerve by an overlying vessel, mostly at the root entry zone is considered to be the major cause of trigeminal neuralgia (TGN). The most prevalently used operation technique in patients with trigeminal neuralgia is the microvascular decompression (MVD)....
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|Summary:||Neurovascular compression of the trigeminal nerve by an
overlying vessel, mostly at the root entry zone is considered to be the major
cause of trigeminal neuralgia (TGN).
The most prevalently used operation technique in patients with trigeminal
neuralgia is the microvascular decompression (MVD). Peter Jannetta was the
first neurosurgeon to apply the operating microscope to the problem of TGN
and devised a technique for nondestructive MVD of the nerve.
Decompression of the nerve root produces a rapid and long-term relief of
symptoms in most patients (80-90%) with vessel-associated TGN.
High-Resolution Magnetic Resonance Imaging (HR-MRI) with special
sequences: 3D-FSPGR und 3D-FIESTA is used in preoperative evaluation of
neurovascular compression in patients with TGN.
To assess whether vascular compression of trigeminal nerve in
patients with trigeminal neuralgia could be demonstrated reliably by
preoperative HR-MRI and how high is the correspondence among MRI
results and intraoperative findings in a single blinded study with retrospective
analysis after deblinding.
We examined preoperatively thirty (30) patients
with TGN with HR-MRI using 3D-FIESTA (three-dimensional fast imaging
employing steady-state acquisition) and double-dose contrast enhanced 3DFSPGR
(three-dimensional fast spoiled gradient-recalled) sequences. These
images and postprocessed multiplanar reconstruction (MPR) images were
analyzed and later compared with intraoperative videoobservations.
Afterwards these results were evaluated in a retrospective analysis of the
In all 30 cases the trigeminal nerve could be seen clearly in the
3D-FSPGR sequence. The MPR provided very good images to evaluate the
fifth cranial nerve. By injection of double dose of Gadolinium-DTPA even
small vessels showed a good enhancement to distinguish them from the
The 3D-FIESTA sequence, additionally performed in 13 patients, was also
able to show the spatial relationships between the structures brilliantly.
In 13 of 30 patients (43.33%) preoperative HR-MRI demonstrated the
neurovascular compression in good agreement with the intraoperative
findings. The noted suspicious side of pathology and also the affected region
of trigeminal nerve were in accordance with the intraoperative findings in 12
of 13 cases.
The assessment of preoperative HR-MRI concerning the side of
neurovascular compression failed in 8 of 30 cases (26.67%).
In 9 remaining patients the postoperative results turned out to be different
as neurovascular compression: demyelination lesion, Teflon® interponate
from previous operation, or neither preoperative MRI on the affected side, nor
intraoperative observations demonstrated neurovascular compression with
evident TGN, so termocoagulation was performed.
So in total preoperative HR-MRI demonstrated the neurovascular
condition in good accordance with the intraoperative observations in 19 of 30
patients (63.33%). MRI failed in 11 of 30 cases (36.67%).
The HR-MRI with special sequences could be objective,
especially when clinical data are not blind to neuroradiologists. In order to get
more precise results, the usage of both high-resolution MR sequences
should be a condition.
Although the HR-MRI is not absolutely reliably in order to show
neurovascular compression, the neurosurgeons still prefer to have
preoperatively the 3D-FSPGR and 3D-FIESTA images, thus knowing
clinically the affected side they are able to improve preoperative preparations
and intraoperative expectations.|