Has MS affected your brainstem and cerebellum?

People with MS who have lesions in the posterior fossa have a poorer prognosis. However, there are things that can be done for each of the problems that arise from posterior fossa involvement.

Do you know if you have any lesions in the part of the brain that is found in the posterior fossa of the skull? This area includes the part of the brain called the brainstem and cerebellum.

Photo by Pawel Czerwinski on Unsplash

 The brainstem is the part of the central nervous system (CNS) between the spinal cord and the so-called cerebral hemispheres. The brainstem consists of three parts the medulla oblongata, pons and midbrain. The brainstem is like a very busy railway junction with many fibre tracts (axons) passing through it on the way to the spinal cord (cerebrospinal) and back from the spinal cord to the brain (spinocerebral). In addition, the brainstem houses many of the so-called autonomic centres that control breathing, blood pressure, pulse rate and swallowing. The brain stem also houses the centres for eye movements, hearing, balance, coordination, walking and the nerve cell bodies of most of the cranial nerves. 

The brainstem is also closely linked to the cerebellum or mini-brain that controls many motor functions. The brainstem and cerebellum are housed in the posterior fossa of the skull. When MS lesions occur in the posterior fossa, i.e. brainstem and cerebellum, they are frequently symptomatic and can be very devastating. People with MS (pwMS) with posterior fossa disease have a worse outcome than those without lesions in this area, which is why I include posterior fossa signs in my prognostic index when advising patients about MS disease-modifying therapies (DMTs). If you have had a recent MRI you should ask your neurologist if you have any lesions in the posterior fossa.

The following is a list of some of the symptoms that can be associated with posterior fossa involvement in MS:

• Double vision

• Oscillopsia (jumping images)

• Jerky eye movements

• Unsteady gait or ataxia

• Incoordination

• Vertigo

• Tinnitus

• Deafness

• Hyperacusis

• Nausea

• Vomiting

• Hiccoughs

• Slurred speech

• Swallowing problems

• Choking

• Loss of taste

• Loss of sensation on the face or in the mouth

• Emotional incontinence or inappropriate crying or laughing

• Hallucinations (pontine hallucinosis). 

• Cognitive impairment

Recently we have begun to identify cognitive impairment has been linked to disease of the cerebellar hemispheres. Typically pwMS with severe cerebellar dysfunction have poor memory and the correct sequencing of memories. PwMS who have severe cerebellar involvement may come across as being very vague. As many fibre tracts pass through the brainstem weakness of the limbs, loss of sensation on the body, bowel, bladder and sexual problems can also occur from brainstem disease. It is clear that the brain stem is a very important structure and needs to be protected from the ravages of MS whenever possible.

There are many specialised neurophysiological techniques to assess brainstem function. Unsurprisingly, pwMS with brainstem involvement have more disability. 

Cardiovascular and autonomic dysfunction is not uncommon in MS and is related to the involvement of the autonomic areas of the brain that supply the heart; these are located in the area of the brain stem called the medulla oblongata. It has been suggested that the involvement of these areas may contribute to the occurrence of sudden death in MS. There are case reports of people with active relapsing-remitting MS who have died unexpectedly due to the sudden onset of cardiac arrhythmias. Post-mortem examinations in these cases have shown the presence of active demyelinating lesions in the medulla oblongata. I suspect, sudden death in MS or SUDMUS may be commoner than we think. In epilepsy, for example, it took decades for neurologists to recognise sudden death in epilepsy or SUDEP as being a problem.

We have meant symptomatic treatments and/or specialised and targeted neurorehabilitation programmes for the problems caused by posterior fossa lesions. If you have any of these symptoms and they are impacting your quality of life and ability to function, please speak to your HCP about them. Over the next few years, I am sure to write individual MS-Selfie Newsletters on each of the specific problems mentioned in the list above.

I’m assuming that knowing how MS can affect the function of different parts of your brain and spinal cord will help you understand your MS. Is my assumption wrong?

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General Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not necessarily reflect the positions of Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust. The advice is intended as general advice and should not be interpreted as being personal clinical advice. If you have problems please tell your own healthcare professional who will be able to help you.