The Sciatica Atlas

The essentials of sciatica

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The Sciatica Atlas is a free, in-progress project covering the essentials of sciatica: what it is, how to assess it, and how to manage it in clinic.

While the site is being built, I’ll share the work here as short, memorable Atlas notes. Each note is meant to be vivid and teachable: stories, analogies, and mnemonics that make ideas click and spread.

Nothing about sciatica is secret. It’s just buried in textbooks, paywalled papers - and books like mine! The Sciatica Atlas takes all that info, simplifies it, and puts it in one accessible place.

Three sample notes are below.

1) The Three M’s of Prognosis

There’s no crystal ball, but according to the research, three things tell us something about whether our patients with sciatica will get better:

• Mindset: Patients who expect to recover are more likely to get better; so are patients who aren't afraid to move. And vice versa. Why? Optimists make better decisions and feel better generally, while pessimists spiral downward. But also: maybe optimists sense their bodies healing, while pessimists sense stagnation; in other words, perhaps both groups correctly anticipate their fate.

• Momentum: Patients improving within the first month typically continue improving. Those stalled at three to four months are less likely to accelerate later. This might seem circular—"people who improve are people who improve"—but the 1-month and 3- to 4-month checkpoints help us to judge when trajectory might become destiny. Note that these time periods are time since starting care, not since the onset of symptoms.

• Multiple symptoms: Patients whose sciatica triggers secondary problems—fatigue, stiffness, problems sitting and sleeping—fare badly.

Perhaps just as interesting is what’s not on that list.

2) Dermatomes: Just Worry About Iowa

Here in America, people like to debate where the Midwest is. Some people say Oklahoma is in the Midwest, some people don't. But few people argue about whether Iowa is in the Midwest.

Dermatomes work similarly. The precise boundaries between L5 and S1 are debated in the literature. The fact is that the borders are naturally fuzzy, and vary between individuals.

As clinicians though, we should focus less on the disputed boundaries and more on the reliable anchors. Few people argue about those: the lateral foot is S1, and the great toe is L5. Iowa is the Midwest.

If you find a loss of sensation at one of these anchors, then that's additional evidence for a radiculopathy. Match it with a pattern, and you're on your way.

3) Referred vs Radicular: The Cloud and The Lightning

What's the difference between radicular pain and referred pain? The simplest answer is 'read Bogduk'. The next simplest answer is below.

Your patient clutches their buttock, but their problem is in their back. A man having a heart attack grabs his arm, though his problem is in his chest.

The brain gets confused when pain originates from deep structures. Papercuts are straightforward; they're right there on the surface. But when pain comes from hearts and spines, we often feel pain in the wrong place.

This is referred pain. A spreading ache. Think of it as the cloud.

Now consider a different scenario where a nerve root becomes injured - let's say a nerve root in the low back. That nerve root's job is simple: carry messages from the leg to the brain. But when it's inflamed, it starts firing its own signals: random bursts that the brain interprets as "this must be coming from the leg."

So that's where you feel it. And it’s not the spreading pattern of referred pain, but a sharper pain, often worst below the knee.

This is radicular pain. An electric jolt. Think of it as the lightning bolt.

Of course, it's often both. A disc herniation, for example, might cause referred pain and radicular pain at the same time. The spreading ache and the electric jolt; the cloud and the lightning bolt.