Rationale:
Symptomatic Occipital Lobe Epilepsy (SOLE) represents an infrequent and diagnostically challenging form of focal epilepsy occurring in patients of all ages. Hallmarked by sensory visual seizures with stereotyped elementary visual hallucinations, a post-ictal migrainous headache commonly lends to a misdiagnosis of migraine with aura. Herein, we describe a pediatric case of SOLE presenting with unilateral visual symptoms due to a rare etiology which highlights the distinguishable and localizing features of SOLE.
Methods:
A 16-year-old female with a history of anxiety and dysautonomia presented for evaluation of seizure-like activity. Initial event featured lightheadedness and tachycardia followed by flashing lights resembling a brown fan in the left temporal visual field. A parent witnessed the episode and described increasing confusion, left gaze deviation with disoriented speech, eyes rolling back and passing out followed by an episode of emesis with return to baseline. A second event several hours later at an outside hospital mirrored the first and progressed to generalized convulsions. On evaluation, neurological exam including confrontational visual fields were normal. The patient complained of an intense headache and continued to see a brown spinning fan exclusively in the temporal field of her left eye for several minutes up to an hour.
Results:
EEG captured multiple episodes of visual hallucinations without discreet electrographic correlate. An MRI Brain with and without contrast revealed a right medial temporooccipital contrast enhancing mass with associated T2 cortical and subcortical changes (Figure 1). Treatment with Levetiracetam abated visual hallucinations and an episode of altered visuospatial awareness occurred on discharge upon arriving home. Subsequent EMU admission also demonstrated normal EEG findings. The patient underwent resection of lesion where pathology findings confirmed a WHO Grade 1 pediatric pilocytic astrocytoma. Genetic analysis revealed BRAF V600E mutation associated with pediatric extra-cerebellar and supratentorial pilocytic astrocytomas. Surgical intervention was well-tolerated and formal post-operative visual fields are pending.
Figure 1: A. Axial FLAIR, B. T1-Post Contrast, C. Coronal FLAIR, D. Sagittal FLAIR; Initial Brain MRI demonstrating signal changes in the posterior mesial temporal lobe with extension to the occipital lobe at the lingual gyrus.
Conclusions:
Our patient presented with classic occipital lobe epilepsy semiology despite a temporooccipital radiographic focus and normal EEG findings. Stereotyped unilateral elementary visual hallucinations suggested an epileptic focus involving the most anteromedial aspect of the visual cortex which MRI findings corroborated (Figure 1). This deep location also explains the lack of scalp EEG correlate during ictal visual manifestations. The absence of complex visual hallucinations points away from involvement or spread to the temporal lobe. Our case emphasizes the importance of recognizing SOLE to avert misdiagnosis, localization of semiology, and surgical management of a rare etiology with a positive outcome.
Funding: None