Tiny Tips: The Ottawa SAH Rule

In Tiny Tips by Brent Thoma2 Comments

This month’s ALiEM Journal Club discussed Perry et al’s 2013 paper Clinical Decision Rules to Rule Out Subarachnoid Hemorrhage for Acute Headache. If you haven’t already, check out the awesome collaborative vodcast featuring ALiEM Editors, Annals of EM Editors and the Authors! If you can’t spare 30 minutes, watch at double speed.

I suspect the Ottawa SAH rule may be destined to join the ranks of Stiell et al’s other Canadian exports (the Canadian CT Head Rule, Canadian C-Spine Rule, and Ottawa Foot/Ankle/Knee Rules) and decided that I needed a way to remember it.

The mnemonic ANT LEaF was derived in my head and validated on Twitter with 8 favorites, 2 retweet and 1 supportive reply in 3 hours:

Mnemonic for the Ottawa SAH Rule: ANT LEaF

A – Age > 40y
N – Neck pain/stiffness
T – Thunderclap onset

L – LOC
E – Exertion onset
a
F – Flexion decreased

It’s not perfect because it has nothing to do with the head, but I hope the association between an ant on a leaf inside a bleeding brain describes a bizarre enough visual to help tie them together. Note that the last letters of each word are the two additional items added to one of the previously derived rules to increase its sensitivity to 100% (95% CI 97.2%-100%) from 98.5% (95% CI 94.6%-99.6%).

Jen Williams (@DrJenWilliams) suggested a slight reorganization of the letters to spell ELeFANT. If this sticks with you better, use it!

As usual, this Tiny Tip will be added to the Boring Cards Tiny Tips deck. For more information and instructions on how to use them, check out the Boring Cards page. Thanks to Perry et al for doing such great work!

Post frequency on BoringEM has decreased dramatically since I started writing at ALiEM and doing a lot more research, but I will continue to put out content intermittently. Please consider following along via email or social media (see the top of the column on the right).

Brent Thoma

Editor at CanadiEM
Dr. Brent Thoma is a medical educator, blogging geek, and trauma/emergency physician who works at the University of Saskatchewan College of Medicine. He founded BoringEM and is the CEO of CanadiEM.