Migraine is a complex neurological disorder known for causing severe, often throbbing, headaches. It is also associated with temporary neurological symptoms, collectively known as aura. Migraines can affect speech, causing disruptions that range from subtle word-finding difficulty to temporary inability to communicate. These speech changes are a form of migraine aura, indicating a transient disturbance in the brain’s normal electrical activity.
Specific Ways Migraines Affect Speech
The disruption of speech during a migraine is typically temporary and falls into specific categories of language difficulty.
Transient Aphasia
One common manifestation is transient aphasia, a temporary impairment of language production or comprehension. People experiencing this may struggle to find the right words or feel that their words are coming out “jumbled.” This difficulty can also extend to reading or writing, as the brain’s ability to process language input and output is compromised.
Dysarthria
Another type of speech issue is dysarthria, which involves slurred or garbled speech. This occurs due to temporary weakness or lack of coordination in the muscles used for speaking. Dysarthria is often associated with migraine with brain stem aura, a specific migraine subtype.
These speech symptoms are transient because they typically resolve completely, generally lasting between 5 and 60 minutes. They usually occur before the headache phase begins, but they can occasionally persist during the headache. In rarer, more severe forms, such as hemiplegic migraine, the speech difficulties may last longer.
The Neurological Basis for Speech Changes
The physiological basis for migraine-related speech problems centers on the phenomenon known as a migraine aura. This aura is a neurological event caused by a wave of altered electrical activity that slowly spreads across the surface of the brain, called cortical spreading depression (CSD). CSD involves an initial burst of nerve cell activity followed by a long period of suppression, which temporarily disrupts normal function.
When this spreading wave of suppression reaches the brain’s language centers, typically located in the left hemisphere, it causes the transient speech issues. The wave travels slowly, moving at approximately 2 to 5 millimeters per minute, which explains why aura symptoms develop gradually. This temporary disruption in electrical activity causes the temporary language impairment, such as aphasia.
The CSD mechanism also causes changes in the brain’s blood vessels. Following the wave of suppression, there is often a reduction in cerebral blood flow in the affected area, known as oligemia. This combination of electrical suppression and altered blood flow temporarily affects the complex neural networks required for language processing.
For individuals who experience more dramatic symptoms like slurred speech or one-sided weakness, the mechanism may involve transient ischemia, a temporary reduction in blood flow. This reduced blood flow can be a factor in the severe hemiplegic migraine. Unlike a stroke, this reduced blood flow in migraine is generally not severe enough to cause permanent brain damage.
Differentiation: When Speech Changes Signal an Emergency
Any new or sudden-onset speech difficulty should always be considered a medical emergency until proven otherwise, as these symptoms closely mimic those of a stroke or a Transient Ischemic Attack (TIA). The most important distinction lies in the speed of symptom onset and the pattern of progression.
Stroke symptoms, including sudden difficulty speaking or slurred speech, typically appear abruptly and reach maximum severity almost instantly. In contrast, migraine aura symptoms tend to develop gradually, slowly spreading and intensifying over several minutes. A migraine-related speech disruption will also usually resolve completely within an hour. If the speech difficulty is accompanied by the classic migraine headache, the presence of a headache does not rule out a stroke.
To quickly evaluate a sudden speech change, the public health mnemonic FAST is advised:
- Face drooping
- Arm weakness
- Speech difficulty
- Time to call emergency services
If a person experiences sudden difficulty speaking along with facial drooping or weakness in one arm, immediate medical attention is necessary. Even if the symptoms resolve quickly, an emergency evaluation is required to identify and address the underlying cause.
A stroke causes permanent damage when blood flow to the brain is cut off, whereas a migraine is a temporary electrical and chemical disturbance. Because the symptoms can be so similar, particularly in cases of hemiplegic migraine, it is safer to seek emergency care for any new stroke-like symptom. Neurological evaluation can help determine if the cause is a benign migraine aura or a more dangerous vascular event.