A Rare Case of a Large, Deceitfully Quiet Brainstem Arteriovenous Malformation Presenting Only as Dizziness

Dizziness is one of the most frequent complaints encountered in the medical practice affecting 15%-20% of adults yearly, and can be challenging to assess. Most patients use dizziness as a non-specific term, and thus suffer prejudice from the physicians’ end and can be disregarded frequently. Dizziness can be a symptom of various diseases, some with sinister pathologies. We present a case of garden-variety vertigo that unfurled to be not-so-simple, emphasizing the importance of a thorough history and physical examination again even in the era of technology. A 32-year-old male patient with no past medical history presented with dizziness, later clarified as gradually progressive vertigo for two years, with unstable gait, dysarthria, and occasional diplopia. Physical examination found sustained nystagmus that changed direction with horizontal gaze, vertical nystagmus with upward gaze, dysarthria, and a wide-based ataxic gait. CT head without contrast revealed indeterminate hypodense areas in the left midbrain, pons, and cerebellar hemisphere. MRI brain identified a 2.8 x 3.4 x 4.2 cm Spetzler-Martin grade IV brainstem arteriovenous malformation (AVM) involving the left midbrain, pons, and cerebellum. Feeders were mostly from the posterior circulation, with three intranidal aneurysms, all draining into the deep venous system. The AVM was deemed inoperable, and the patient was treated with onyx embolization for two/three feeding vessel aneurysms. After treatment, the symptoms persisted, and the patient was diagnosed with major depressive disorder (MDD) six months after diagnosis, and was admitted a year later with suicidal ideation and substance use disorder. Brain AVMs are rare clinical entities that present in 0.1% of the population, mostly presenting as intracranial bleeds. When they do rarely present with isolated focal neurologic deficits, it has been attributed to a vascular steal phenomenon, hemorrhage, or a mass effect. The isolated findings of vertigo and dysarthria are highly non-specific; with such presentation, clinicians should consider etiologies under the realm of vertigo of central origin. An untreatable AVM reduces patients’ quality of life and has been linked to depression and anxiety, and thus patients may benefit from psychosocial therapy. Although preventing intracranial hemorrhage (ICH) is the primary concern with brain AVMs, the rest of the patient’s profile should not be forgotten.