Answer for BIR CoW 17 Oct 2021
LEFT TRIGEMINAL NEURALGIA DUE TO NEUROVASCULAR COMPRESSION
Findings
Vascular loop from right anterior inferior cerebellar artery seen indending the cisternal segment of right trigeminal nerve without causing significant distortion. Vascular loop from left anterior inferior cerebellar artery seen indending the cisternal segment of left trigeminal nerve causing significant distortion and atrophy of the nerve. Right trigeminal nerve measures 2.3 mm and left trigeminal nerve measures 1.0 mm. Significant reduction in FA values on the left side noted with increase in ADC values , on comparison with non symptomatic right side.
Discussion
Trigeminal neuralgia (TN) is a debilitating disorder that presents with a sudden onset of severe, unilateral, paroxysmal, and lancinating pain in one or more of the distributions of the trigeminal nerve. Vascular compression of the trigeminal nerve is the most common cause. Other causes include tumors, arachnoid cysts, idiopathic inflammation, injury, demyelination (e.g., multiple sclerosis), and others. Operative treatments for TN include microvascular decompression (MVD) and a variety of ablative procedures of gasserian ganglion like percutaneous balloon rhizotomy, percutaneous glycerol rhizotomy, and percutaneous radiofrequency rhizotomy. In MVD, the compressing or contacting vessel is decompressed or transposed from the trigeminal nerve and permanently separated from the trigeminal nerve, typically with hand-rolled pledgets made of soft material .Of all the operative procedures for TN, MVD is the most durable with the lowest risk of sensory deficits. DTI Alterations in a diffusivity index, the fractional anisotropy (FA) of the trigeminal nerve, are present in patients with trigeminal neuralgia (TN) and can be identified by using anatomic MR imaging coregistered with diffusion-tensor imaging. Diffusion-tensor imaging enables the analysis of white matter integrity by means of in vivo measurement of molecular diffusivity. Fractional anisotrophy (FA) represents a robust method of assessing the degree of directionality of diffusion (ie, anisotropic diffusion) that occurs in a particular region. FA is a measure of the coherence of the underlying microstructure and has been shown to correlate both with axonal counts and myelin content. Apparent diffusion coefficient (ADC), is a quantitative measure of water motility (independent of orientation) in a certain voxel. Degeneration or damage of white matter tracts is expected to result in reduced FA owing to the loss of directionality of diffusion and the increase in ADC that are due to diffusivity being averaged in all spatial directions as a result of the loss of myelin and axonal membranes. In conclusion, diffusion-tensor imaging combined with structural MR imaging is a powerful tool and surrogate in–vivo marker for visualization of microstructural changes based on FA and ADC in symptomatic patients of trigeminal neuralgia due to neurovascular compression.
REFERENCES
Trigeminal Neuralgia due to Neurovascular Compression: High-Spatial-Resolution Diffusion-Tensor Imaging Reveals Microstructural Neural Changes. Juergen Lutz, Jennifer Linn, Jan H. Mehrkens, Niklas Thon, Robert Stahl, Klaus Seelos, Hartmut Brückmann, and Markus Holtmannspötter.Radiology 2011 258:2, 524-530. https://doi.org/10.1148/radiol.10100477 Zhang Y, Mao Z, Cui Z, Ling Z, Pan L, Liu X, Zhang J, Yu X. Diffusion Tensor Imaging of Axonal and Myelin Changes in Classical Trigeminal Neuralgia. World Neurosurg. 2018 Apr;112:e597-e607. doi: 10.1016/j.wneu.2018.01.095. Epub 2018 Feb 2. PMID: 29410338. Leal, P.R.L., Roch, J., Hermier, M. et al. Diffusion tensor imaging abnormalities of the trigeminal nerve root in patients with classical trigeminal neuralgia: a pre- and postoperative comparative study 4 years after microvascular decompression. Acta Neurochir 161, 1415–1425 (2019). https://doi.org/10.1007/s00701-019-03913-5
Findings
Vascular loop from right anterior inferior cerebellar artery seen indending the cisternal segment of right trigeminal nerve without causing significant distortion. Vascular loop from left anterior inferior cerebellar artery seen indending the cisternal segment of left trigeminal nerve causing significant distortion and atrophy of the nerve. Right trigeminal nerve measures 2.3 mm and left trigeminal nerve measures 1.0 mm. Significant reduction in FA values on the left side noted with increase in ADC values , on comparison with non symptomatic right side.
Discussion
Trigeminal neuralgia (TN) is a debilitating disorder that presents with a sudden onset of severe, unilateral, paroxysmal, and lancinating pain in one or more of the distributions of the trigeminal nerve. Vascular compression of the trigeminal nerve is the most common cause. Other causes include tumors, arachnoid cysts, idiopathic inflammation, injury, demyelination (e.g., multiple sclerosis), and others. Operative treatments for TN include microvascular decompression (MVD) and a variety of ablative procedures of gasserian ganglion like percutaneous balloon rhizotomy, percutaneous glycerol rhizotomy, and percutaneous radiofrequency rhizotomy. In MVD, the compressing or contacting vessel is decompressed or transposed from the trigeminal nerve and permanently separated from the trigeminal nerve, typically with hand-rolled pledgets made of soft material .Of all the operative procedures for TN, MVD is the most durable with the lowest risk of sensory deficits. DTI Alterations in a diffusivity index, the fractional anisotropy (FA) of the trigeminal nerve, are present in patients with trigeminal neuralgia (TN) and can be identified by using anatomic MR imaging coregistered with diffusion-tensor imaging. Diffusion-tensor imaging enables the analysis of white matter integrity by means of in vivo measurement of molecular diffusivity. Fractional anisotrophy (FA) represents a robust method of assessing the degree of directionality of diffusion (ie, anisotropic diffusion) that occurs in a particular region. FA is a measure of the coherence of the underlying microstructure and has been shown to correlate both with axonal counts and myelin content. Apparent diffusion coefficient (ADC), is a quantitative measure of water motility (independent of orientation) in a certain voxel. Degeneration or damage of white matter tracts is expected to result in reduced FA owing to the loss of directionality of diffusion and the increase in ADC that are due to diffusivity being averaged in all spatial directions as a result of the loss of myelin and axonal membranes. In conclusion, diffusion-tensor imaging combined with structural MR imaging is a powerful tool and surrogate in–vivo marker for visualization of microstructural changes based on FA and ADC in symptomatic patients of trigeminal neuralgia due to neurovascular compression.
REFERENCES
Trigeminal Neuralgia due to Neurovascular Compression: High-Spatial-Resolution Diffusion-Tensor Imaging Reveals Microstructural Neural Changes. Juergen Lutz, Jennifer Linn, Jan H. Mehrkens, Niklas Thon, Robert Stahl, Klaus Seelos, Hartmut Brückmann, and Markus Holtmannspötter.Radiology 2011 258:2, 524-530. https://doi.org/10.1148/radiol.10100477 Zhang Y, Mao Z, Cui Z, Ling Z, Pan L, Liu X, Zhang J, Yu X. Diffusion Tensor Imaging of Axonal and Myelin Changes in Classical Trigeminal Neuralgia. World Neurosurg. 2018 Apr;112:e597-e607. doi: 10.1016/j.wneu.2018.01.095. Epub 2018 Feb 2. PMID: 29410338. Leal, P.R.L., Roch, J., Hermier, M. et al. Diffusion tensor imaging abnormalities of the trigeminal nerve root in patients with classical trigeminal neuralgia: a pre- and postoperative comparative study 4 years after microvascular decompression. Acta Neurochir 161, 1415–1425 (2019). https://doi.org/10.1007/s00701-019-03913-5
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!