Reflections on Medical Education: Localisation of seizures 🧠

When someone has a seizure, the symptoms can tell us more than just what happened — they give clues about where in the brain it happened. Seizure localisation is the art and science of mapping signs and behaviours to specific cortical regions. From staring spells to sudden muscle jerks, each presentation points to a unique neural epicentre.

Understanding where seizures begin helps us decode the circuitry behind them, guides diagnosis, and even shapes treatment decisions. Let’s explore how brain geography becomes clinical insight.

🧠 Focal seizures begin in a specific cortical region and may spread.

🧠 Generalised seizures involve both hemispheres from the onset.

(see the blog post on seizure classification for more details)

🔎 Clinical Reasoning: The Art of Localisation

🧭 Step 1: Describe the Event

Start with a clear seizure history:

What did the patient experience first? (Aura, motor/sensory symptoms?)
Was awareness preserved?
How did the event evolve?
Was there postictal confusion or sleepiness?

🧭 Step 2: Map Symptoms to Brain Regions

Symptom	Likely Cortical Origin
Right arm jerking	Left motor cortex
Tingling in leg	Contralateral sensory cortex
Word salad	Wernicke’s area
Speech arrest	Broca’s area
Flashing lights or visual aura	Occipital lobe
Lip-smacking, fumbling, confusion	Temporal lobe (association cortex)
Emotional aura (e.g., fear)	Amygdala / temporal lobe

👩‍⚕️ Important tip: Aura symptoms can act as a spotlight—illuminating where the seizure begins. Automatisms often point to temporal lobe involvement, especially if awareness is impaired.

Now let’s take a walk through the cortex as a whole and learn how different brain regions contribute to function—and what happens when those regions misfire, like in seizures.

Understanding this helps you localise where a seizure starts, which is a vital clinical skill! 🧠💥

🔑 Functional Zones of the Brain

Think of the cerebral cortex as a control panel with different buttons for movement, sensation, language, and thought. If one of those buttons gets “stuck” or “short circuits,” we see seizure symptoms related to that region.

1️⃣ Motor Cortex (Orange) – “The Movement Hub”

📍 Located in the frontal lobe, just in front of the central sulcus.
🧠 Controls voluntary movements (like waving a hand).
⚡ Seizures here → jerking, twitching, or stiffening, usually on the opposite side of the body.
Example: Left motor cortex → Right hand jerking.

2️⃣ Sensory Cortex (Blue) – “The Feeling Station”

📍 Just behind the central sulcus in the parietal lobe.
🧠 Processes touch, temperature, and pain.
⚡ Seizures here → sensory auras like tingling, pins and needles, or numbness.

3️⃣ Association Cortex (Pink/Green) – “The Think Tank”

🧠 Integrates input from different areas → involved in decision-making, memory, and interpreting information.
⚡ Seizures can cause confusion, loss of awareness, or strange behaviours like lip-smacking or repeating motions (called automatisms).

🗣️ Language Areas – Speak & Understand

🧠 Broca’s Area (frontal lobe)

🗣️ Controls speech production.
⚡ Seizures → inability to speak or sudden speech arrest.

🧠 Wernicke’s Area (temporal lobe)

🗣️ Handles language comprehension.
⚡ Seizures → word salad, where speech may sound fluent but lacks meaning.

👁️ Visual Cortex (Green) – “The Sight Centre”

📍 Located in the occipital lobe.
⚡ Seizures → visual hallucinations, flashing lights, or zigzag shapes.

👂 Auditory Cortex (Purple) – “The Sound System”

📍 In the temporal lobe.
⚡ Seizures → auditory hallucinations, like buzzing, ringing, or hearing voices.

🧠 Zoom In: The Temporal Lobe Example

Why do temporal lobe seizures often cause strange behaviours and emotional changes?

The temporal lobe houses the limbic system, including the hippocampus and amygdala—areas involved in memory, emotion, and automatisms.
Focal seizures here can spread subtly, preserving awareness initially, and then evolving into more complex semiology.
Patients may describe déjà vu, fear, or hearing voices—classic limbic activation.
When seizures disrupt these deep structures, especially in the medial temporal lobe, awareness may fade—not because the lights are off, but because the spotlight is focused inward. Patients may stare, chew, or fumble without conscious recognition, as the seizure hijacks their behavioural scripts.

🧲 EEG and Imaging: Connecting Symptoms to Signals

Once you've localised symptoms anatomically, the next step is confirming them physiologically. EEG can capture abnormal electrical activity, showing where the brain misfires. MRI or CT may reveal structural causes—like a scar, lesion, or tumour. But your clinical map often predicts the findings before you even open the scanner room

🤔 Clinical Pearl

Seizure symptoms point to function—and function points to anatomy!
A twitch in the right hand? That’s likely the left motor cortex at work.
Hearing buzzing? 🧠 You’re probably in the auditory cortex.

💡 So Why Does This Matter?

Understanding where seizures begin helps you:

🔬 Determine the cause
💊 Tailor treatment plans
🧠 Guide surgery decisions
👩‍⚕️ Interpret patient symptoms accurately

Want to test your localisation skills? Try this:

“A patient reports seeing flashing lights and then temporarily loses awareness. Where might the seizure have started?” What do you think?

💭 Final Thought: From Cortex to Clinic

Understanding seizure symptoms as a reflection of cortical function helps move from descriptive to diagnostic thinking. When a patient presents with a focal symptom, first-years can begin reasoning:

“What function is being disrupted?”
“Where in the brain does that happen?”
“What conditions might affect that region?”

That diagnostic map starts forming before the EEG or MRI—and that’s the beauty of clinical neuroanatomy.

📦 Want to learn more?

Reflections on Medical Education

Tuesday, 22 July 2025

Localisation of seizures 🧠