Red flags in headache

What it is

Headache is pain due to irritation of structures such as the dura, the cranial nerves, or extracranial structures, and it divides into two classes. Primary headaches are migraine, tension-type, cluster and others such as cold stimulus headache. Secondary headaches are those attributed to another disorder: head or neck trauma, a cranial or cervical vascular disorder, a nonvascular intracranial disorder, substance use or withdrawal, infection, disturbance of homeostasis, or a psychiatric disorder; and headache or facial pain attributed to a disorder of the cranium, neck, eyes, ears, nose, sinuses, teeth, mouth or other facial or cranial structures. The named secondary causes include subarachnoid hemorrhage, meningitis, hydrocephalus, neoplasia and giant cell or temporal arteritis.

The red flags are the findings in a headache that move it out of the primary class and into the secondary one.

How it presents

The red flags are held in SNOOP4E, the 4 standing for the four P flags that follow the two O flags:

Systemic symptoms, illness, or condition: cancer, chills, fever, immunocompromise, infection, myalgias, night sweats, pregnancy or postpartum, weight loss.
Neurologic symptoms or abnormal signs: confusion, diplopia, focal neurologic signs, impaired consciousness, meningismus, pulsatile tinnitus, seizures.
Onset with maximal intensity within minutes, the thunderclap headache.
Older, that is age 50 years or above at onset.
Progression, a change in features, in pattern or in severity.
Precipitated by Valsalva.
Postural aggravation.
Papilledema.
Exertional provocation.

The same list written out for the history:

Sudden onset within seconds to minutes.
The worst headache of the patient's life.
A new-onset headache the patient has never experienced before, especially over the age of 50 years.
A headache pattern that increases in severity and frequency over time, and is worse after lying down.
Mental status change, or any focal neurologic symptoms or signs.
New-onset headache with heavy exertion or head trauma.
New-onset headache with fever, stiff neck, or rash.
New-onset headache in a patient with HIV infection or cancer.