Substance P concentration in human amniotic membrane.

involution of the pituitary tumor, the chiasm itself may herniate into an enlarged and relatively empty sella. In some cases, this may result in traction and kinking of axons with renewed loss of function. Likewise, although the intracranial pressure diminishes following cerebrospinal fluid leaks, deterioration of visual function can also be expected when the brain, no longer buoyed by fluid, settles onto the skull base and compresses the chiasm with pressure points between the brain and pituitary fossa. Keeping such alternative processes in mind, one can comprehend the futility of using functional testing such as visual evoked potentials to monitor the progression of optic gliomas. To summarize, spontaneous regression of gliomas is not a rare occurrence and can be accompanied by loss of vision. Some medical practitioners misinterpret loss of function, either clinically or by means such as visual evoked potentials, as evidence of tumor progression. This can misguide them to initiate unproven treatment modalities for gliomas that are already beginning to shrink. They may subsequently attribute efficacy to a purported remedy for an eventually detected reduction of glioma size. Particularly when trying to assess the beneficial effects of future therapies in investigational trials, such errors should not be allowed to occur.