A trigger (from the Dutch trekken, meaning to pull) is a lever which, when pulled by the finger, releases the hammer on a firearm. In a database, a trigger is a set of Structured Query Language (SQL) statements that automatically fires off an action when a specific operation, such as changing data in a table, occurs. A trigger consists of an event (an INSERT, DELETE, or UPDATE statement issued against an associated table) and an action (the related procedure).
There are a wide variety of conditions that can be considered in the differential diagnosis of a Chiari malformation. The symptoms commonly associated with a Chiari malformation are vague and common to numerous other conditions. Some disorders are common misdiagnoses for individuals with a Chiari malformation. Such conditions include multiple sclerosis, chronic fatigue syndrome, fibromyalgia and spinal cord tumors.
Visual symptoms include retro-orbital pain, flashing lights or floaters, blurred vision, photophobia, diplopia, transient vision loss, and peripheral vision loss. Objective evidence is often lacking in these patients; however, horizontal or vertical nystagmus is present in up to 45% of those with Chiari I malformation.