How MS Affects the Brainstem

Brainstem lesions can impair key motor and sensory functions

Multiple sclerosis (MS) produces neurological symptoms due to its effect on the brain, spinal cord, and optic nerves (the nerves that control vision). When areas affected by the disease (lesions) include the brainstem—the lowest part of the brain (right above the spinal cord)—it can cause blurred or double vision, trouble swallowing, slurred speech, dizziness, coordination problems, weakness, and decreased sensation.

A brain magnetic resonance imaging (MRI) scan and occasionally evoked potential tests are used to detect MS lesions in the brainstem.

Prevention of MS brainstem problems relies on the same disease-modifying treatments (DMTs) used to prevent MS progression. But the management of neurological problems caused by brainstem lesions is often based on therapy and safety measures that specifically address resulting symptoms.

MS Symptoms Unique to Brainstem Lesions
Verywell / Emily Roberts

Brainstem Basics

The brainstem is small in length and width, but it is an important region of the brain where many nerve pathways meet.

Messages between the cerebral cortex, subcortical regions, cerebellum, and spinal cord all travel through the brainstem. And the cranial nerves, which control eye movements, facial sensation, facial movements, and basic functions of survival (such as breathing), emerge from the brainstem.

The brainstem has three sections:

  • The midbrain: Located at the top end of the brainstem, it coordinates sight, sound, and body movement. It also regulates arousal and alertness and helps control eye movements.
  • The pons: Situated in the middle part of the brainstem, it's involved in breathing, sleep, hearing, taste, sensation, and movement of the face as well as with balance.
  • The medulla oblongata: Located in the lower portion of your brainstem, it helps regulate your heart rate and blood pressure. It also coordinates involuntary reflexes such as coughing, sneezing, and vomiting.

How MS Affects the Brainstem

MS primarily affects the white matter of the central nervous system. White matter is located in deeper areas of the brain described as the subcortical and periventricular regions as well as in the outer portions of the spinal cord.

The white matter of the brainstem can be affected by MS demyelination. The process makes nerves slow down to the point of not functioning, producing the characteristic signs and symptoms of MS brainstem lesions.

Highly myelinated (coated with protected fat) nerves are called white matter because they appear white on microscopic examination.

Symptoms of Brainstem Involvement in MS

MS causes a wide range of symptoms because the areas it can affect in the brain and spinal cord control so many bodily functions.

Many of the sensory and motor symptoms of MS brainstem lesions are similar to symptoms of lesions of the spine and other parts of the brain because those in the brainstem often interrupt nerve pathways that connect to these regions.

Symptoms that result from brainstem lesions (which can also occur with MS lesions elsewhere) include:

  • Impaired strength or control of movements
  • Slurred speech
  • Decreased sensation to touch, pain, temperature, and vibration
  • Diminished balance
  • Trouble sleeping

Additionally, brainstem involvement in MS affects cranial nerve functions, which causes symptoms that are not produced by MS lesions in other locations, including:

  • Diplopia (double vision) or jerky eye movements
  • Hearing impairment, including deafness, tinnitus (ringing in the ears), or noise intolerance
  • Diminished sense of taste
  • Facial weakness
  • Dysphagia—swallowing problems, including choking, coughing, or gagging
  • Facial pain or altered facial sensation
  • Vertigo (a sense that your surrounding are spinning)
  • Problems with blood pressure, heart rate, or breathing (all very rare in MS)

Diagnosis

Your doctor may identify a brainstem lesion based on your history and physical examination. However, because many of the signs and symptoms of brainstem lesions in MS are the same as those of other MS lesions, diagnostic tests can help identify where your MS lesions are located.

Brain and spine MRI is commonly used in MS. This test detects areas of acute and chronic demyelination and can help determine whether you have lesions that correspond to your signs and symptoms. Sometimes in MS, the brainstem may appear small due to atrophy, which is shrinking of the nerves and their myelin.

Auditory and vestibular evoked potentials may be used in certain cases when an MS lesion is suspected and MRI is negative or inconclusive.

Treatment

There are a number of DMTs used for the management of MS, and these medications are used to prevent MS exacerbations (relapses). There are also treatments used to hasten the resolution of relapses and prevent long-term neurological damage.

In addition, rehabilitation, including physical therapy and occupational therapy, can help you optimize your motor strength and coordination.

Swallowing assessment and swallow therapy can help you eat and drink more comfortably and may help prevent complications of dysphagia, such as choking and aspiration pneumonia.

Your doctor or therapist may also recommend corrective lenses or an eye patch to help manage diplopia. And hearing problems may necessitate the use of a hearing aid.

A Word From Verywell

MS can affect any part of the brain, spinal cord, and optic nerves. MS lesions in the brainstem often produce effects that are less obvious than weakness or sensory loss. But these lesions can have a major impact on your quality of life and may put you at risk of serious medical complications.

If you are having subtle symptoms, such as coughing when you eat, you might not realize that this is part of your MS. Be sure to discuss such symptoms with your medical team. Often, there are solutions that can help.

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