Imaging diagnosis
Case 218
【Progress】
His symptoms of nausea with tinnitus were abated by reducing his medicines given from the local clinic.
【Discussion】
Cerebellum is thought to evolve from flocculo-nodular lobe (nodule corresponded to a part of vermis), followed by vermis and then, cerebellar hemisphere (1). Flocculus and nodulus communicate to vestibular organs, get information of head posture from semicircular canals and functions to maintain equilibrium (vestibular route). Vermis except nodulus communicate to spine, get information of impulses from muscles related to standing, in other words, anti-gravitation, vermis output to red nucleus, thalamus, caudate, putamen. It functions subconscious movement (extrapyramidal route). Cerebellar hemispheres communicate to cerebrum cortex (Brodmann 4 and 6) and red nucleus, get information of intension movement from cerebrum cortex and output to the same area of cerebrum cortex, and functions intension movement (pyramidal route). Additionally, cerebellar cortex gets information of revised intention movement from cerebrum cortex, red nucleus and olive, inducing to function coordinated movement (1).
All inflow impulse to cerebellum eventually come into Purkinje cells where all outflow impulse generate. Outflow impulse has to go through cerebellar nucleus; vestibular impulse heads for fastigii nucleus; extrapyramidal impulse heads for globosus nucleus and emboliformis nucleus: pyramidal impulse heads for dentate nucleus (1).
Dentate nucleus plays a role of transit for output impulse of pyramidal route. Input impulse of pyramidal route comes from cerebral cortex in the frontal lobe, transits at pons and eventually reaches to cerebellar cortex of Purkinje cells. Output impulses arisen from Purkinje cells transit to dentate nucleus, and then, come out from cerebellum to thalamus, transit again at thalamus and eventually reaches to cerebral cortex again where output impulse once emerged. Then, the revised impulse head for spinal cord via pyramidal route. As another route of output impulses from dentate nucleus, they head for red nucleus and transit to go for Olive in the medulla oblongata and transit there to go into Purkinje cells as input information, making a circuit probably because of ordination of the movement. Namely, dental nucleus functions to coordinate intention movement of pyramidal tract. The reason why the impulse arisen from dentate nucleus goes not only thalamus but to red nucleus is probably to coordinate intention (pyramidal) movement to non-intention (extrapyramidal) movement.
When high signal intensity of dentate nucleus appears on MRI with T2WI and FLAIR, the following disease are listed: metronidazole side effect, Wernicke syndrome, multiple sclerosis (2-6). Metronidazole is one of the antibiotics for treating Amebiasis, Trichomoniasis, Clostridium difficille (whose toxin causes pseudo-membrane colitis) (2-6). In our case, patient suffered from liver abscess and antibiotics were given, one of them probably used metronidazole for a while, inducing metronidazole-induced encephalopathy.
【Summary】
We presented a seventy one-year-old male for persistent nausea. He was given antibiotics from the local hospital where he was admitted for liver abscess. Brain MRI with Diffusion WI, T2WI and FLAIR depicted a lesion with high signal intensity at bilateral cerebellar dentate nucleus. ADC values were not lowering, indicating edema of the lesion. It is borne in mind that cerebellum three main functions to preserve head posture via vestibular route, and to stand, walk and run with two legs via extrapyramidal route and pyramidal route. Dentate nucleus is a transition point of output impulse from Purkinje cells to cerebral cortex at frontal lobe (pyramidal tract) via thalamus. Dental nucleus is also a transition point of impulses from Purkinje cells to red nucleus (extrapyramidal tract) which outputs to Olive and returns to Purkinje cells making a circuit. Dental nucleus encephalopathy can occur due to administration of metronidazole, Vitamin B1 deficiency and multiple sclerosis.
【References】
1.Peter Duus. Neurologisch-topische Diagnostik: Anaromie・Physiologie・KlinikFeder JM, et-al. 1983. Bunkodo. Translated in Japanese.
2.Kim E et al. MR Imaging of Metronidazole-Induced Encephalopathy: Lesion Distribution and Diffusion-Weighted Imaging Findings. American Journal of Neuroradiology October 2007, 28 (9) 1652-1658
3.Freeman CD, Klutman NE, Lamp KC. Metronidazole: a therapeutic review and update. Drugs 1997;54:679–708
4.Frytak S, Moertel CH, Childs DS. Neurologic toxicity associated with high-dose metronidazole therapy. Ann Intern Med 1978;88:361–62
5.Snavely SR, Hodges GR. The neurotoxicity of antibacterial agents. Ann Intern Med 1984;101:92–104
6.Bradley WG, Karlsson IJ, Rassol CG. Metronidazole neuropathy. BMJ 1977;2:610–11
2021.1.20