Facial Paralysis and Horner Syndrome

Body paralysis and paraparesis are well-known outcomes of brain injury (including stroke) and spinal cord injury. However, one type of paralysis that is less often discussed is facial paralysis and Horner syndrome.

The face is managed by cranial nerves which are nerves that exit at the back of the brain. They manage functions and sensations in the face, head, neck, and torso. Although the cranial nerves are spoken about as one, they are actually a pair that split with one for each side of the body. This is why you may have paralysis on one side of your face and not the other.

The cranial nerves are always referred to as the name of the nerve and a Roman Numeral for distinction. Some cranial nerves are motor nerves to create movement, some are sensory nerves, and some do both motor and sensory functions. Below is a chart of the cranial nerves, their name, and their function. Some functions are performed by a combination of cranial nerves.

Injury to the facial nerve (Cranial Nerve VII) is the most common of all cranial nerve injuries. Most cranial nerve injuries are in males, ages 30-50 years, but no one is exempt from the potential for injury of cranial nerves. Facial nerve injuries are most often due to skull base fractures because of the origin of cranial nerves at the brain stem, which is at the skull base. The symptoms of any cranial nerve injury basically are numbness or tingling in the area the cranial nerve controls, pain, skin sensitivity, and weak or paralyzed muscles. The location of the symptoms depends on which cranial nerve is affected.

Facial paralysis can be a warning sign of an impending health issue or the result of a medical concern. For example, droopiness of the face on one side, a droopy eyelid, or uncontrolled saliva on one side of the mouth are signs of a stroke or trans ischemic attack (TIA). If you develop these symptoms, call 911, as a stroke is evolving. These same issues can also be consequences of a stroke or brain injury due to a blood clot or ruptured blood vessel pressing on the cranial nerves that serve these facial structures. A traumatic brain injury can place pressure on the cranial nerves as well.

Some medical conditions can affect your facial nerves such as Bell’s palsy. The cause of Bell’s palsy is unknown, but it is suspected to be caused by a virus. It affects Cranial Nerve VII (7), the facial nerve causing one side of your face to droop. You may or may not have difficulty chewing due to biting the inside of your mouth or swallowing. Bell’s palsy typically resolves on its own, however, if the effects are long-term, Botox might be used on the non-effected side to even out facial balance.

Trigeminal neuralgia is an issue with Cranial Nerve V (5), the trigeminal nerve. This can lead to excruciating nerve pain. Medication for nerve pain such as gabapentin or pregabalin may be used to control pain.

Another issue is hemifacial spasm, which is a muscle that twitches around the eye or on the face. These are usually temporary, lasting for a short period of time. If prolonged or if uncomfortable, Botox injections may be used.

In the eye, issues with the cranial nerves may include internuclear ophthalmoplegia, which is loss of synchronized eye movement, or oculomotor palsy, which typically affects the movement of one eye. Both are treated with therapies by ophthalmologists, or physical or occupational therapists educated in these therapies. If hearing is affected in one or both ears, an audiologist may be a part of the rehabilitation team as well.

Diseases such as amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), diabetes, and hypertension, among others can affect facial functions as well due to disease processes. Pharmacological treatments for diseases as well as therapy to improve facial function will aid in helping to control the progression of these health concerns.

Besides a physical examination and medical history, other tests may be performed such as a magnetic resonance image (MRI), magnetic resonance angiography (MRA) to examine your blood vessels, or computerized tomography (CT) scan. If the nerves affected are within the peripheral nervous system (outside of the central nervous system of the brain and spinal cord), nerve grafting or transfers may be used to boost the effectiveness of the affected nerves. This is currently not a first-line treatment but is used in more severe cases. An expert in nerve surgery is needed to perform these procedures.

Horner syndrome (oculosympathetic paresis) is a facial paralysis that can be the result of a brain injury, stroke, spinal cord injury, or medical disease. It can even occur spontaneously or have a genetic origin. In this syndrome, the face and eye on one side of the body are affected. If there is facial swelling at the time of a brain injury, the syndrome may not be noticed right away. In spinal cord injury, Horner syndrome appears in individuals with a lower cervical or upper thoracic level injury. In some cases of brain injury, including stroke, and spinal cord injury or disease, autonomic dysreflexia can be associated with Horner syndrome.

Symptoms of Horner syndrome include a decreased pupil size, slower response pupil, droopy eyelid, a lower eyelid that does not open completely, a sunken appearance to the eye, and decreased sweating on one side of the face. This is because sympathetic nerves (those that increase body activity) or a combination of cranial nerves have been injured in some way.

Diagnosis of Horner syndrome is most typically done by history and physical assessment. A test sometimes performed is by use of an eye drop, apraclonidine. When instilled into the eye in individuals without Horner syndrome, there is no dilation of the eye pupil. If there is dilation of the pupil, Horner syndrome may be diagnosed.

Often, Horner syndrome improves if there is a medical condition that is treated. As the medical condition improves, so does the Horner syndrome. In cases of brain injury or spinal cord injury, the syndrome may improve over time as strength gains in the muscles around the eye and face. Therapy can help improve function through the use of strengthening exercises for muscles and nerves around the eye and face. This may be provided by a physical therapist, occupational therapist, and speech and language therapist working together.

Facial paralysis can be striking or quite subtle. Families are key to noticing the more subtle signs as you know the individual best. Be sure to discuss your concern with the healthcare professional to obtain prompt treatment.

Pediatric Consideration:

Infants may have cranial nerve symptoms from overstretching the neck during childbirth. The initial post-birth examination may demonstrate issues with cranial nerve functions, however, occasionally, the symptoms may be slight and not seen until later after birth.

Horner syndrome can occur at any age, but it can also be a complication of birth as well. In children under the age of one, the color of the iris may be lighter than the other eye. Also, there may be less color to the cheek, especially when crying.