| Pseudobulbar palsy | |
|---|---|
| Specialty | Neurology |
Pseudobulbar palsy is a medical condition characterized by the inability to control facial movements (such aschewing andspeaking) and caused by a variety ofneurological disorders. Patients experience difficulty chewing and swallowing, have increasedreflexes andspasticity in tongue and thebulbar region, and demonstrateslurred speech (which is often the initial presentation of the disorder), sometimes also demonstrating uncontrolled emotional outbursts.[1]
The condition is usually caused by the bilateral damage tocorticobulbar pathways, which areupper motor neuron pathways that course from thecerebral cortex to nuclei ofcranial nerves in thebrain stem.
Signs and symptoms of pseudobulbar palsy include:
Pseudobulbar palsy is the result of damage ofmotor fibers traveling from thecerebral cortex to the lower brain stem. This damage might arise in the course of a variety of neurological conditions that involvedemyelination and bilateral corticobulbar lesions. Examples include:[3]
The proposed mechanism of pseudobulbar palsy points to thedisinhibition of themotor neurons 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.[5] The pseudobulbar crying could also be induced by stimulation in the region of thesubthalamic nucleus of the brain.[6]
Diagnosis of pseudobulbar palsy is based on observation of the symptoms of the condition. Tests examiningjaw jerk andgag reflex 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.[7] To further confirm the condition, MRI can be performed to define the areas of brain abnormality.[citation needed]
Since pseudobulbar palsy is a syndrome associated with other diseases, treating the underlying disease may eventually reduce the symptoms of pseudobulbar palsy.[citation needed]
Possible pharmacological interventions for pseudobulbar affect include thetricyclic antidepressants,serotonin reuptake inhibitors, and a novel approach utilizingdextromethorphan andquinidine 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.[5]