Brainstem Stroke Symptoms, Diagnosis, and Syndromes

A stroke can affect any location in the brain. A brainstem stroke is usually small in size but may cause substantial symptoms.

The brainstem is the region of the brain that physically and functionally connects higher-level brain activity with the rest of the body. It is also the control center for several life-sustaining functions, such as breathing and heart regulation. The brainstem is located deep in the brain and extends down towards the back of the head, right where the skull and the spine meet.

A brainstem stroke is the result of the interruption of blood flow within small arteries in the back of the neck and brain, such as the basilar artery, the right or left posterior inferior cerebellar artery, or the right or left vertebral artery. The causes of brainstem stroke are the same as the causes of strokes in other regions of the brain.

Symptoms

A brainstem stroke can cause a range of symptoms, including:

• Weakness or sensory deficits may occur on the side of the body opposite the damaged side of the brainstem.
• Double vision can result, because control of eye movements is located in the brainstem. When one eye is not able to move as well as the other normal eye, the lack of symmetric movement produces the perception of two images. Uneven pupils are also associated with brainstem stroke.
• Dizziness or sensations of spinning are common with a brainstem stroke, because the sense of balance is maintained in the brainstem.
• Uneven facial and mouth muscle strength may cause one of the eyelids to droop or one side of the mouth to sag. It can also cause difficulty with swallowing or slurred speech, or may make the tongue point to one side.
• Weakness of the shoulders can manifest as an inability to evenly shrug the shoulders.
• In a severe stroke, postures such as decerebrate posture

One of the characteristics that distinguishes a brainstem stroke from a stroke of the cerebral cortex is the effect on facial sensation. When a brainstem stroke produces a sensory deficit of the face, the face is numb on the same side as the stroke. This is in contrast to a stroke of the cerebral cortex, which causes a sensory deficit on the opposite side of the face. This is one of the clues that a neurologist uses to diagnose a brainstem stroke.

In some instances, a brainstem stroke can cause hiccups. It also can result in loss of consciousness due to the brainstem’s role in regulation of breathing and heart function.

Brainstem Stroke Syndromes

Some brainstem stroke syndromes include a collection of seemingly unrelated symptoms that occur together because their control lies in tiny concentrated regions of the brainstem that share the same blood supply:

• Ondine’s curse: Ondine's curse affects voluntary breathing due to a lesion of the lower medulla.
• Webers syndrome: Webers syndrome is a midbrain stroke that causes weakness of the opposite side of the body combined with eyelid weakness and weakness of eye movements on the same side.
• Locked-in syndrome: Locked in syndrome is a stroke that affects the pons and results in complete paralysis and the inability to speak, with intact consciousness and ability to move the eyes. It can result from exceedingly abnormal salt and fluid balance.
• Wallenberg syndrome: Also called lateral medullary syndrome, Wallenberg syndrome characteristically causes sensory deficit of the face on the same side as the stroke and sensory deficit of the body on the opposite side of the stroke.

Diagnosis

Diagnosis of brainstem strokes requires a detailed understanding and experience with neurological disease. Brainstem strokes are usually not as evident on a brain CT or brain MRI as strokes in other locations of the brain. The brainstem is relatively small and is often difficult to visualize due to the nearby bone of the skull and upper portion of the spine.

Often a brainstem stroke manifests with subtle clinical findings diagnosed by a thorough clinical examination, and it may take days to weeks for the changes corroborating with the clinical assessment to appear on imaging studies.

Prognosis

As with strokes in other regions of the brain, the prognosis of a brainstem stroke varies. Stroke symptoms usually reach peak severity in the hours and days immediately following the initial onset of stroke before beginning to heal. Careful medical monitoring and care can help maximize recovery and decrease disability after a brainstem stroke.