Downbeat Nystagmus in Metronidazole Neurotoxicity
Bibliographic record
Abstract
We report a case of downbeat nystagmus due to metronidazoleinduced neurotoxicity and its implications.A 74-year-old woman presented with subacute onset of disequilibrium, nausea, imbalance, and falls.She also complained of vertical oscillopsia, transient diplopia, limb incoordination, dysarthria, and distal paresthesias.She had longstanding ulcerative colitis with prior colectomy and internal pouch and had been taking metronidazole continuously for 12 years.Examination revealed DBN in all directions of gaze (including upgaze).Saccades and pursuit were normal apart from interruptions by nystagmus.There was mild dysarthria, subtle left upper limb dysmetria, and dysdiadochokinesia.Ankle reflexes and distal lower extremity vibration sense were reduced, and she walked with a narrow base with occasional veering to either side and was unable to perform tandem gait.Other medical history included hypertension.There was no previous history of liver or kidney disease, diabetes, or cancer.There was no family history of neurological disease.MRI brain revealed multiple T2/FLAIR hyperintensities within the splenium of the corpus callosum (Figure 1a-c).These lesions demonstrated restricted diffusion.There were additional T2/FLAIR hyperintensities in the periventricular, subcortical, and deep white matter which did not restrict diffusion and were in keeping with chronic microangiopathic disease.Additionally, the following tests were normal/negative: complete blood count, fasting glucose, HbA1c, electrolytes, creatinine, liver function tests, thyroid stimulating hormone, vitamins B1, B6, B12, and E, magnesium, antinuclear antibodies, extractable nuclear antigen panel, antineutrophil cytoplasmic antibodies, anti-GAD65 antibodies, anti-tissue transglutaminase antibodies, deamidated antigliadin antibodies, full paraneoplastic antibody panel and genetic testing for common spinocerebellar ataxias, routine CSF testing and oligoclonal bands, and whole body PET scan.Discontinuation of metronidazole led to significant improvement in gait and speech within 8 months although the oscillopsia, disequilibrium, and DBN did not resolve after discontinuation.Similarly, there was no improvement with 4-aminopyridine, clonazepam, gabapentin, baclofen, or memantine.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.002 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.004 | 0.003 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".