The first indicator of increasing intracranial pressure is..?

Varies: This may vary depending on the rapidity of the increase in intracranial pressure (icp). In cases such as strokes or aneurysms or head trauma where there is an acute rise in icp, altered level of consciousness and coma are the usual presenting symptoms. If the icp is gradually increasing such as with a growing tumor, symptoms include headache, nausea/vomiting, blurred or double vison.

HA & papilledema: Headache, and papilledema or elevated edematous optic nerve are the first signs of increased intracranial pressure. 95% of cases are pseudo-tumor cerebri or idiopathic intracranial hypertension, or "glaucoma of brain" same medication treats it. If in doubt we get the neurosurgeon to do a spinal tap. Real tumors are rare and usually have local signs, like dr. Chen has mentioned.