Pseudobulbar palsy is a medical condition characterized by the inability to control facial movements (such as

chewing Chewing or mastication is the process by which food is crushed and ground by the teeth. It is the first step in the process of digestion, allowing a greater surface area for digestive enzymes to break down the foods. During the mastication proc ...

and

speaking Speech is the use of the human voice as a medium for language. Spoken language combines vowel and consonant sounds to form units of meaning like words, which belong to a language's lexicon. There are many different intentional speech acts, su ...

) and caused by a variety of

neurological disorder Neurological disorders represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These disorders affect the brain, spinal cord, and nerve networks, presenting unique diagnosis, treatment, and ...

s. Patients experience difficulty chewing and swallowing, have increased

reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...

es and

spasticity Spasticity () is a feature of altered skeletal muscle performance with a combination of paralysis, increased tendon reflex activity, and hypertonia. It is also colloquially referred to as an unusual "tightness", stiffness, or "pull" of muscles. ...

in tongue and the bulbar region, and demonstrate slurred speech (which is often the initial presentation of the disorder), sometimes also demonstrating uncontrolled emotional outbursts. The condition is usually caused by the bilateral damage to corticobulbar pathways, which are

upper motor neuron Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex and brainstem and carry information down to activate interneurons and lower motor neurons, which in turn directly signal muscles ...

pathways that course from the

cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. It is the largest site of Neuron, neural integration in the central nervous system, and plays ...

to nuclei of

cranial nerve Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), of which there are conventionally considered twelve pairs. Cranial nerves relay information between the brain and parts of the body, primarily to and f ...

s in the

brain stem The brainstem (or brain stem) is the posterior stalk-like part of the brain that connects the cerebrum with the spinal cord. In the human brain the brainstem is composed of the midbrain, the pons, and the medulla oblongata. The midbrain is co ...

Signs and symptoms

Signs and symptoms of pseudobulbar palsy include: * Slow and indistinct speech *

Dysphagia Dysphagia is difficulty in swallowing. Although classified under " symptoms and signs" in ICD-10, in some contexts it is classified as a condition in its own right. It may be a sensation that suggests difficulty in the passage of solids or l ...

(difficulty in swallowing) * Small, stiff and spastic tongue * Brisk jaw jerk *

Dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. It is a condition in which problems effectively occur with the ...

Labile affect Pseudobulbar affect (PBA), or emotional incontinence, is a type of affect disorder connected to neurological conditions. It is characterized by brief, intense, uncontrollable episodes of crying or laughing. The affect is triggered by emotion ...

Gag reflex The pharyngeal reflex or gag reflex is a reflex muscular contraction of the back of the throat, evoked by touching the roof of the mouth, back of the tongue, area around the tonsils, uvula, and back of the throat. It, along with other aerodigest ...

may be normal, exaggerated or absent * Examination may reveal upper motor neuron lesion of the limbs

Causes

Pseudobulbar palsy is the result of damage of motor fibers traveling from the

to the lower brain stem. This damage might arise in the course of a variety of neurological conditions that involve demyelination and bilateral corticobulbar lesions. Examples include: *

Progressive supranuclear palsy Progressive supranuclear palsy (PSP) is a late-onset neurodegenerative disease involving the gradual deterioration and death of specific volumes of the brain, linked to 4-repeat tau pathology. The condition leads to symptoms including Balance di ...

Amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States—Lou Gehrig's disease (LGD), is a rare, Terminal illness, terminal neurodegenerative disease, neurodegenerative disorder that results i ...

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor system, motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become ...

and related

multiple system atrophy Multiple system atrophy (MSA) is a rare neurodegenerative disorder characterized by tremors, slow movement, muscle rigidity, postural instability (collectively known as parkinsonism), autonomic dysfunction and ataxia. This is caused by progr ...

* Various

motor neuron disease Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States—Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and low ...

s, especially those involving demyelination *

Multiple sclerosis Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit ...

and other inflammatory disorders * Vascular lesions * High

tumors * Metabolic causes: osmotic demyelination syndrome] * Neurological involvement in Behçet's disease * Brain trauma

Pathophysiology

The proposed mechanism of pseudobulbar palsy points to the

disinhibition Disinhibition, also referred to as behavioral disinhibition, is medically recognized as an orientation towards immediate gratification, leading to impulsive behaviour driven by current thoughts, feelings, and external stimuli, without regard for ...

of the

motor neuron A motor neuron (or motoneuron), also known as efferent neuron is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside of the spinal cord to directly o ...

s controlling laughter and crying, proposing that a reciprocal pathway exists between the cerebellum and the brain stem that adjusts laughter and crying responses, making them appropriate to context. The pseudobulbar crying could also be induced by stimulation in the region of the subthalamic nucleus of the brain.

Diagnosis

Diagnosis of pseudobulbar palsy is based on observation of the symptoms of the condition. Tests examining jaw jerk and

gag reflex The pharyngeal reflex or gag reflex is a reflex muscular contraction of the back of the throat, evoked by touching the roof of the mouth, back of the tongue, area around the tonsils, uvula, and back of the throat. It, along with other aerodigest ...

can also be performed. It has been suggested that the majority of patients with pathological laughter and crying have pseudobulbar palsy due to bilateral corticobulbar lesions and often a bipyramidal involvement of arms and legs. To further confirm the condition, MRI can be performed to define the areas of brain abnormality.

Treatment

Since pseudobulbar palsy is a syndrome associated with other diseases, treating the underlying disease may eventually reduce the symptoms of pseudobulbar palsy. Possible pharmacological interventions for pseudobulbar affect include the

tricyclic antidepressant Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants. TCAs were discovered in the early 1950s and were marketed later in the decade. They are named after their chemical structure, which contains ...

serotonin reuptake inhibitor A serotonin reuptake inhibitor (SRI) is a type of drug which acts as a reuptake inhibitor of the neurotransmitter serotonin (5-hydroxytryptamine, or 5-HT) by blocking the drug action, action of the serotonin transporter (SERT). This in turn lea ...

s, and a novel approach utilizing

dextromethorphan Dextromethorphan, sold under the brand name Robitussin among others, is a cough suppressant used in many cough and Common cold, cold medicines. In 2022, the US Food and Drug Administration (FDA) approved the combination dextromethorphan/bupropi ...

and quinidine sulfate. Nuedexta is an FDA approved medication for pseudobulbar affect. Dextromethorphan, an N-methyl-D-aspartate receptor antagonist, inhibits glutamatergic transmission in the regions of the brainstem and cerebellum, which are hypothesized to be involved in pseudobulbar symptoms, and acts as a sigma ligand, binding to the sigma-1 receptors that mediate the emotional motor expression.

References

External links

{{Diseases of the nervous system Motor neuron diseases