Visual evoked potentials in patients with pineal gland cyst.

Aims: The functional effect of the pineal gland cyst is difficult to evaluate with visual field examination. The aim of this study is to investigate the usefulness of visual evoked potentials (VEP) in patients with pineal gland cyst due to the possible compression on the visual pathway.

Subjects And Methods: Black-and-white pattern-reversal checkerboard VEP were recorded in 75 patients (50 females and 25 males, mean age 26.3 ± 15.7 and 25.6 ± 17.6 years, respectively) with pineal gland cyst detected on magnetic resonance of the brain (subject group) and 75 age and sex-matched control subjects (control group). Amplitudes and P100 latencies were collected and later grouped as: (1) normal finding; (2) prechiasmal; (3) prechiasmal and postchiasmal; and (4) postchiasmal dysfunction.

Results: P100 latencies differed significantly between subject (110.26 ± 13.23 ms) and control group (101.01 ± 5.36 ms) (p < 0.01). Findings of the VEP differed significantly (p < 0.01) between subject and control group, mainly due to the postchiasmal dysfunction frequency in subject group. Findings of the VEP differed significantly according to the pineal gland cyst volume (p = 0.006) with more frequent postchiasmal dysfunctions among subjects with larger cysts. Postchiasmal changes were significantly more frequent in patients with described compression of the cyst on surrounding brain structures (p = 0.016).

Conclusions: Postchiasmal dysfunction on VEP can be seen in patients with pineal gland cyst, mostly with larger cysts and with compression of the cyst on surrounding brain structures. VEP serve as a useful method to determine functional impairment of the visual pathway in patients with pineal gland cyst.