The key difference between UMN and LMN facial palsy is that in UMN (upper motor neuron lesions) facial palsy, the forehead is not affected, while in LMN (lower motor neuron lesions) facial palsy, the forehead is affected.
Facial palsy refers to weakness in facial muscles due to temporary or permanent damage to facial nerves. It is mainly of two types: UMN and LMN facial palsy. In UMN facial palsy, the forehead is not affected, and the patient is able to fully raise an eyebrow on the affected side. On the other hand, in LMN facial palsy, the forehead is affected, and the patient is unable to raise the affected eyebrow.
CONTENTS
1. Overview and Key Difference
2. What is UMN Facial Palsy
3. What is LMN Facial Palsy
4. Similarities – UMN and LMN Facial Palsy
5. UMN vs LMN Facial Palsy in Tabular Form
6. Summary – UMN vs LMN Facial Palsy
What is UMN Facial Palsy?
UMN (upper motor neuron lesions) facial palsy is a type of facial palsy in which the forehead is not affected. As the forehead is not affected, the patient is able to raise his eyebrows fully on the affected side. Upper motor neuron lesions usually occur due to injury or abnormality in the neural pathway above the anterior horn cell of the spinal cord or motor nuclei of the cranial nerves. Upper motor neuron lesions normally occur in the brain or the spinal cord as the result of stroke, traumatic brain injury, multiple sclerosis, cerebral palsy, atypical parkinsonisms, multiple system atrophy, amyotrophic lateral sclerosis, intracranial tumor, syphilis, HIV, vasculitides, or hemorrhage. The sign of UMN facial palsy includes normal or increased extensor tone and normal or exaggerated reflexes on the face. In some cases, abnormal reflexes may be seen.
UMN facial palsy can be diagnosed through physical examination, CT scan, MRI, nerve conduction study, spinal tap or lumbar puncture, and nerve biopsy. Furthermore, treatments for UMN facial palsy may include stimulation, physiotherapy, facial reanimation surgery, and static surgery.
What is LMN Facial Palsy?
LMN facial palsy is a type of facial palsy where the forehead is affected. Lower motor neuron lesions are normally due to damaged nerve fibers traveling from the anterior horn of the spinal cord or the cranial motor nuclei to the relevant muscles. As the forehead is affected, the patient is unable to raise eyebrows on the affected side. The causes of LMN facial palsy may include idiopathic or Bell’s palsy, tumor, infection (Ramsay Hunt syndrome, Lyme disease), iatrogenic nerve damage, congenital, and rare conditions like neurosarcoidosis, otitis media, multiple sclerosis, Moebius syndrome, Melkersson Rosenthal syndrome, Guillain Barre syndrome, etc. The signs of LMN facial palsy are rapid onset of mild weakness to total paralysis on one side of the face, face droop and difficulty making expression, pain around the jaw in or behind the ear, increased sensitivity to sound on the affected side, headache, loss of taste and changes in the amount of tears and saliva the patient produces.
LMN facial palsy can be diagnosed through CT scan, MRI, nerve conduction studies, electromyography, Sunnybrook facial grading system, and House Brackmann facial nerve grading scale. Furthermore, the treatment options for LMN facial palsy include corticosteroids (prednisone) and antiviral medications, surgeries, physiotherapy (neuromuscular retraining, trophic electrical stimulation, proprioceptive neuromuscular facilitation technique, Kabat technique, etc.
What are the Similarities Between UMN and LMN Facial Palsy?
- UMN and LMN facial palsy are two different types of facial palsy that are categorized under peripheral facial palsy.
- Both types are diagnosed through physical examination and nerve conduction studies.
- They are treated through physiotherapy and surgeries.
What is the Difference Between UMN and LMN Facial Palsy?
UMN facial palsy is a type of facial palsy in which the forehead is not affected, while LMN facial palsy is a type of facial palsy in which the forehead is affected. Thus, this is the key difference between UMN and LMN facial palsy. Furthermore, in UMN facial palsy, the patient is able to raise the eyebrow fully on the affected side, but in LMN facial palsy, the patient is unable to raise the eyebrow on the affected side.
The below infographic presents the differences between UMN and LMN facial palsy in tabular form for side-by-side comparison.
Summary – UMN vs LMN Facial Palsy
Facial palsy is a condition that refers to the weakness of the facial muscles, mainly due to temporary or permanent damage to facial nerves. UMN and LMN facial palsy are two different types of facial palsy. UMN facial palsy is a type of facial palsy where the forehead is not affected, while LMN facial palsy is a type of facial palsy where the forehead is affected. So, this is the key difference between UMN and LMN facial palsy.
Reference:
1. “What Is Facial Palsy?” Facial Palsy UK, 14 Feb. 2022.
2. “Facial Palsy.” Physiopedia.
Image Courtesy:
1. “Bells palsy diagram” By Patrick J. Lynch, medical illustrator – Patrick J. Lynch, medical illustrator (CC BY 2.5) via Commons Wikimedia