|LETTER TO THE EDITOR
|Year : 2021 | Volume
| Issue : 1 | Page : 46-47
Mineralization of the fascicula nigrale
Shweta Prasad1, Jitender Saini2, Pramod Kumar Pal3
1 Department of Clinical Neurosciences and Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India
2 Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India
3 Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, Karnataka, India
|Date of Submission||01-Jul-2020|
|Date of Decision||04-Aug-2020|
|Date of Acceptance||05-Sep-2020|
|Date of Web Publication||17-Apr-2021|
Dr. Pramod Kumar Pal
Department of Neurology, National Institute of Mental Health & Neurosciences, Bengaluru 560029, Karnataka.
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Prasad S, Saini J, Pal PK. Mineralization of the fascicula nigrale. Ann Mov Disord 2021;4:46-7
The fascicula nigrale, that is, the nigropallidal pathway, was first described in imaging by Harder et al., as a mineralized structure extending from the substantia nigra to the medial aspect of the globus pallidus. The role of the fascicula nigrale in extrapyramidal iron transport is controversial with contradictory reports.,
A 53-year-old man presented with a 3-year history of right upper limb (UL) tremor, and 2-year history of bradykinesia. He had no other complaints and no relevant family history. Examination revealed asymmetric (right > left) tremor, rigidity, and bradykinesia Parkinsonism More Details. His unified Parkinson’s disease rating scale-III OFF score was 25 and based on the clinical findings and levodopa responsiveness, he was diagnosed with tremor dominant Parkinson’s disease (PD). MRI brain revealed no abnormalities in T1, T2, or FLAIR sequences. Susceptibility weighted images (SWI) of the brain (number of echoes:4, minimum echo time: 7.2 milliseconds (ms), echo spacing: 6.2ms, repetition time: 31ms, flip angle: 17°, voxel size: 0.6mmx0.6mmx2.0mm, FOV: 23cm, acquisition time: 3 minutes 28 seconds) revealed loss of nigrosome-1 in bilateral substantia nigra, and slightly asymmetrical (left > right) mineralization of a well demarcated curved path between the substantia nigra and the pallidum, i.e. the fascicula nigrale [Figure 1].
|Figure 1: Consecutive susceptibility weighted images from the substantia nigra to the pallidum showing mineralization of the fascicula nigrale (white arrow)|
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PD is associated with loss of dopaminergic projection neurons of the substantia nigra, and pathological abnormalities in the nigrostriatal and nigropallidal pathways. Several studies have reported the presence of increased mineralization of the substantia nigra in PD, and a rostral-caudal pattern of iron deposition in the fascicula nigrale has also been described.
In addition, compensatory neural plasticity involving the nigropallidal pathway in early stages of PD has also been reported. SWI is generated from gradient-echo pulse sequences which use differences in tissue magnetic susceptibility to generate unique contrasts. This is particularly sensitive to iron (ferritin or hemosiderin), deoxygenated blood, and calcium. Owing to which, this sequence is frequently used to identify deposition of these compounds.
Although often described in theory, the nigropallidal pathway, that is, the fascicula nigrale is seldom visualized on imaging. Further exploration of this tract may lead to a better understanding of connections of the substantia nigra, and their involvement in PD.
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Conflicts of interest
There are no conflicts of interest.
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