Considered separately, fluoxetine use in children increased the odds of suicidality by 50%, and in adults decreased the odds of suicidality by approximately 30%. A study published in May 2009 found that fluoxetine was more likely to increase overall suicidal behavior. 14.7% of the patients (n = 44) on fluoxetine had suicidal events, compared to 6.3% in the psychotherapy group and 8.4% from the combined treatment group. Similarly, the analysis conducted by the UK MHRA found a 50% increase in suicide-related events, not reaching statistical significance, in the children and adolescents on fluoxetine as compared to the ones on placebo. According to the MHRA data, fluoxetine did not change the rate of self-harm in adults and statistically significantly decreased suicidal ideation by 50%. QT prolongation
Fluoxetine can affect the electrical currents that heart muscle cells use to coordinate their contraction, specifically the potassium currents Ito and IKs that repolarise the cardiac action potential. Under certain circumstances, this can lead to prolongation of the QT interval, a measurement made on an electrocardiogram reflecting how long it takes for the heart to electrically recharge after each heartbeat. When fluoxetine is taken alongside other drugs that prolong the QT interval, or by those with a susceptibility to long QT syndrome, there is a small risk of potentially lethal abnormal heart rhythms such as torsades de pointes. A study completed in 2011 found that fluoxetine does not alter the QT interval and has no clinically meaningful effects on the cardiac action potential.
In most cases there are other neurological abnormalities, such as seizures and weakness of part of the body, but in 15–30% the headache is the only abnormality.Carotid artery dissection and vertebral artery dissection (together cervical artery dissection), in which a tear forms inside the wall of the blood vessels that supply the brain, often causes pain on the affected side of the head or neck. The pain usually precedes other problems that are caused by impaired blood flow through the artery into the brain; these may include visual symptoms, weakness of part of the body, and other abnormalities depending on the vessel affected. Diagnosis
The most important initial investigation is computed tomography of the brain, which is very sensitive for subarachnoid hemorrhage. If this is normal, a lumbar puncture is performed, as a small proportion of SAH is missed on CT and can still be detected as xanthochromia.If both investigations are normal, the specific description of the headache and the presence of other abnormalities may prompt further tests, usually involving magnetic resonance imaging (MRI). Magnetic resonance angiography (MRA) may be useful in identifying problems with the arteries (such as dissection), and magnetic resonance venography (MRV) identifies venous thrombosis. It is not usually necessary to proceed to cerebral angiography, a more precise but invasive investigation of the brains blood vessels, if MRA and MRV are normal. Epidemiology
Incidence of thunderclap headache has been estimated at 43 per 100,000 people every year. Approximately 75% are attributed to "primary" headaches: headache disorder, non-specific headache, idiopathic thunderclap headache or uncertain headache disorder.