A stroke occurs when blood flow to a part of the brain is interrupted, either by a blockage or bleeding, leading to the rapid death of brain cells. This sudden event can result in lasting brain damage, causing various physical and cognitive challenges. Dysphagia, difficulty swallowing, is a common and serious complication that can arise after a stroke. It affects the complex process of moving food or liquid from the mouth to the stomach, impacting a person’s ability to eat and drink safely.
Understanding Stroke Types
Strokes are broadly categorized into two main types based on their underlying cause. An ischemic stroke happens when a blood vessel supplying the brain becomes blocked, typically by a blood clot, preventing necessary oxygen and nutrients from reaching brain tissue. This accounts for the majority of strokes, around 87%. Brain cells begin to die within minutes when deprived of this vital blood supply.
In contrast, a hemorrhagic stroke occurs when a blood vessel in the brain ruptures, causing bleeding into or around the brain. This accumulated blood puts pressure on brain cells, damaging them. Though less common (about 13% of all strokes), they can lead to significant brain injury. Both types of stroke can disrupt normal brain function, including the intricate mechanisms of swallowing.
Stroke Locations and Their Impact on Swallowing
While any stroke can potentially lead to dysphagia, the specific area of the brain affected significantly influences the likelihood and severity of swallowing difficulties. The brain controls swallowing through various regions. Damage to these specific areas can disrupt the neural pathways and motor control necessary for safe and effective swallowing.
Strokes occurring in the brainstem are a primary cause of severe dysphagia. The brainstem contains crucial cranial nerves and central pattern generators that coordinate the involuntary phases of swallowing. Damage here can lead to significant impairment in muscle control and coordination of the throat and larynx.
Cortical strokes, which affect the brain’s outer layer, can also cause dysphagia by impacting areas involved in the voluntary aspects of swallowing. The motor and premotor cortices, particularly the precentral gyrus, control the muscles of the face, lips, tongue, and throat involved in chewing and moving food. The insular cortex plays a role in integrating sensory information and initiating the swallow reflex, so damage to this area, especially on the right side, is often linked to swallowing problems. Additionally, lesions in the frontal and parietal lobes can disrupt the planning and sensory feedback essential for coordinated swallowing.
Cerebellar strokes, while less frequently discussed, can also contribute to dysphagia. The cerebellum is vital for motor coordination, balance, and fine-tuning movements. Damage to the cerebellum can impair the precise timing and coordination required for swallowing, leading to issues with the oral and pharyngeal phases. Around 52.9% of individuals experience dysphagia after a cerebellar stroke.
How Stroke Affects Swallowing
A stroke can lead to dysphagia by disrupting the swallowing process. Stroke can impair motor control, affecting the strength and movement of muscles in the mouth, throat, and larynx. This can result in weakness or paralysis of the tongue, lips, and pharyngeal muscles, making it difficult to chew food, form a food bolus, or propel it through the throat.
Sensory impairment also impacts swallowing. Reduced sensation in the mouth or throat means a person may not detect food or liquid, or recognize when it enters the airway. This lack of awareness can delay the swallow reflex and increase aspiration risk.
Coordination problems are also common, as swallowing requires precise timing and sequencing of muscle movements. A stroke can disrupt this intricate coordination, leading to uncoordinated swallowing actions that increase the risk of choking or aspiration, where food or liquid enters the lungs.
Cognitive issues, such as impaired attention or awareness, can affect a person’s ability to safely manage food and drink. This includes problems with sequencing eating steps or paying attention during mealtimes.
Recognizing Dysphagia Post-Stroke
Identifying dysphagia after a stroke involves observing signs during or after eating and drinking. Common indicators include coughing or choking during or immediately after consuming food or liquids. A wet or gurgly voice after swallowing suggests food or liquid has entered the airway.
Other signs of dysphagia include:
- Sensation of food sticking in the throat or chest.
- Repeated swallowing attempts to clear the throat.
- Drooling or leakage of food and liquid from the mouth.
- Food or liquid coming back up through the nose.
- Unexplained weight loss.
- Signs of dehydration.