Bulbar Palsy · What Is It, Causes, Diagnosis, Treatments, and More

Bulbar palsy refers to a set of signs and symptoms that result from damage to the cranial nerves responsible for controlling the muscles involved in speech, swallowing, and facial movement. The affected cranial nerves are a set of nerves that arise from the bulbar region of the brainstem and include cranial nerves IX (glossopharyngeal), X (vagus), XI (accessory), and XII (hypoglossal).  

Bulbar palsy can be classified as progressive or non-progressive depending on whether the condition worsens over time or remains stable. Progressive bulbar palsy is more common and refers to the escalation of symptoms over time. It is often associated with neurodegenerative disorders like amyotrophic lateral sclerosis, or ALS. Non-progressive bulbar palsy, on the other hand, refers to bulbar palsy that does not worsen; it’s considered very uncommon and is often the result of structural brain damage from trauma, stroke, or congenital disorders rather than a degenerative condition. 

Bulbar palsy is sometimes confused with pseudobulbar palsy, which is the result of damage to the upper motor neurons in the corticobulbar tract, a neural pathway that connects the brain’s motor cortex to the brainstem. While the two conditions share many of the same symptoms, pseudobulbar palsy is often characterized by the atypical expression of emotion displayed by unusual outbursts of laughing or crying, called emotional lability. Meanwhile, with bulbar palsy, an individual’s emotions usually remain unaffected. Other differentiating signs and symptoms of pseudobulbar palsy include spasticity in facial muscles, resulting in difficulty expressing emotions, and exaggerated reflexes, such as an increased jaw jerk reflex and gag reflex.  

One of the most common causes of bulbar palsy includes brainstem strokes and tumors. The brainstem is the part of the brain where the cranial nerves arise from and where all motor control signals are transmitted. Thus, damage to the brainstem—from strokes, tumors, or other causes—can damage various cranial nerves and disrupt motor control. 

Other common causes of bulbar palsy include neurodegenerative diseases, most commonly amyotrophic lateral sclerosis; autoimmune diseases like Guillain–Barré syndrome; and genetic causes such as Kennedy disease. Amyotrophic lateral sclerosis is a rare neurological disorder characterized by a gradual deterioration and death of both upper and lower motor neurons. Progressive bulbar palsy is a specific form of ALS where degeneration occurs primarily in the brainstem, affecting speech and swallowing first. 

Guillain–Barré syndrome causes the immune system to attack the myelin sheath or axons of peripheral nerves, leading to loss of sensation and muscle weakness in various parts of the body. Symptoms typically start in the legs and move upwards, but in some cases, they can affect the cranial nerves, leading to bulbar palsy.  

Finally, Kennedy disease is a lower motor neuron disease that can affect transmission signals between the brain and the spinal cord, resulting in both limb and bulbar muscle dysfunction. 

Yes, some cases of bulbar palsy can be hereditary, even though it’s not the most common presentation. For example, Kennedy disease is a rare, X-linked recessive neuromuscular disorder that primarily affects males. It’s caused by a mutation in the androgen receptor (AR) gene located on the X chromosome. Since males only have one X chromosome, they are typically affected, whereas females are usually asymptomatic carriers and may show only mild symptoms. 

Other forms of hereditary bulbar palsy include Brown–Vialetto–Van Laere (BVVL) and Fazio–Londe syndromes. BVVL is an autosomal recessive disorder, which means that both parents may be carriers for the disease without expressing the condition themselves but can pass on the expressive form of the disease to their child. Fazio–Londo syndrome presents similarly and is inherited in a similar manner to BVVL. 

Signs and symptoms of bulbar palsy depend on the cranial nerve that is damaged. For example, cranial nerve IX (glossopharyngeal nerve) is involved in salivation, swallowing, and the gag reflex. If cranial nerve IX is injured, it can lead to difficulty swallowing and a reduced gag reflex.  

Common signs and symptoms of damage to the other bulbar cranial nerves include difficulty chewing, nasal regurgitation, slurred speech, aspiration of secretions, impaired speech, and difficulty articulating words.  

Other clinical signs associated with bulbar palsy include a nasal speech that lacks in modulation (e.g., difficulty controlling or adjusting one’s speech), difficulty pronouncing certain consonants, wasting of the tongue, drooling, and weakness of the jaw and facial muscles. Additionally, individuals typically have a normal or absent jaw jerk (i.e., upward jerk of the jaw upon striking the chin) and an absent gag reflex. 

Treatment of bulbar palsy depends on its specific cause, as bulbar palsy itself is a symptom rather than a disease. With ALS, treatment may include disease-modifying agents, including riluzole and edaravone, which can help slow progression of disease. Alternatively, Guillain-Barré syndrome may be treated with medications that suppress the immune system, like corticosteroids and intravenous immunoglobulins. 

In addition to specific treatment, all individuals with bulbar palsy can benefit from supportive measures to improve their quality of life. For example, individuals with difficulty swallowing may use modified dietary textures (e.g., thickened liquids, pureed foods) and postural techniques to reduce the risk of choking and aspiration pneumonia. In severe cases or with progressive conditions like ALS, nutritional support with a feeding tube may be indicated. 

If bulbar weakness leads to respiratory failure, individuals may be recommended non-invasive ventilation to reduce breathing effort or a tracheostomy (i.e., breathing tube), depending on the severity of the condition.  

Other supportive treatments may include speech therapy and medications to reduce excessive drooling, such as anticholinergics (e.g., glycopyrrolate, scopolamine patches), as well as muscle relaxants and physical therapy to improve spasticity.  

Bulbar palsy can be fatal in progressive cases. Death from progressive bulbar palsy often occurs 1 to 3 years from the start of the disorder, however, it is often attributed to the development of complications, most commonly aspiration pneumonia. Aspiration pneumonia happens when someone accidentally breathes in food, drinks, or even gastric contents. It tends to occur in people with impaired gag and cough reflexes, such as those with bulbar palsy.  

Extensive bulbar damage may also damage the respiratory center in the brainstem, which is involved in signaling and controlling breathing. This can lead to a life-threatening inability to breathe properly. Additionally, progressive bulbar palsy may advance to ALS and prognosis is usually poor. With ALS, death of motor neurons interferes with an individual’s ability to breathe and can ultimately be fatal.