Long-term postoperative evaluation of memory impairment caused by the giant great superficial petrosal nerve schwannoma in the left temporal lobe

Background: Great superficial petrosal nerve (GSPN) schwannoma is an extremely rare benign tumor arising from the parasympathetic component of the facial nerve. While typical clinical manifestations include facial nerve palsy, parasympathetic dysfunction, and hearing disturbance, central neurological symptoms such as cognitive impairment have rarely been described. Case Description: We report a case of a woman in her 40s presenting with progressive memory impairment over 9 months, followed by acute deterioration of consciousness. Neuroimaging revealed a large heterogeneous mass in the left temporal region with significant mass effect. Emergency surgical decompression was performed, and histopathological examination confirmed schwannoma, likely originating from the GSPN. Postoperatively, the patient developed transient facial nerve palsy, which gradually improved. Neuropsychological assessment using the Wechsler Memory Scale-Revised, initiated 1 week after surgery, demonstrated severe memory impairment initially, followed by marked and sustained recovery over a 1-year period. The patient’s cognitive impairment was likely attributable to mechanical compression of medial temporal structures and disruption of functional networks. The significant postoperative improvement suggests that such deficits may be reversible following decompression. Conclusion: This case highlights an atypical presentation of GSPN schwannoma without classic cranial nerve symptoms and underscores the importance of considering mass effect-related cognitive dysfunction in large skull base tumors. GSPN schwannoma may present with isolated and progressive memory impairment due to compression of medial temporal structures. Surgical decompression can lead to substantial recovery of cognitive function, suggesting a reversible pathophysiological mechanism. Longitudinal neuropsychological evaluation is valuable for assessing postoperative recovery and functional outcomes.