Rapidly Progressive Dementia Secondary to Vitamin B12 Deficiency: A Case Report.

Abstract

Introduction: While vitamin B12 deficiency is classically associated with hematological abnormalities and subacute combined degeneration, its presentation as rapidly progressive cognitive decline with episodic movement disorders remains an underrecognized clinical phenomenon. This case highlights the diagnostic challenges posed by such non-classical neurological manifestations and underscores the need for increased clinical suspicion in cases of unexplained cognitive-motor decline.

Case presentation: A patient presented with rapidly progressive memory impairment and episodic limb tremors in the absence of overt hematological signs. Serum anti-parietal cell antibody (Anti- PCA) was positive (++; titer 1:32), and anti-intrinsic factor antibody (Anti-IFA) was positive (+) in the patient. Extensive diagnostic workup ruled out common neurodegenerative and structural causes, leading to the detection of severe vitamin B12 deficiency. Initiation of high-dose B12 replacement therapy resulted in marked improvement in both cognitive function and tremor control over subsequent weeks.

Conclusion: This case illustrates that vitamin B12 deficiency can manifest as a rapidly progressive neurocognitive disorder mimicking neurodegenerative conditions. It emphasizes the importance of routinely assessing B12 status in patients with unexplained cognitive and movement abnormalities, as timely intervention can prevent irreversible neurological injury and yield significant clinical improvement.