Cerebellar MS: A Case Study
Kenneth G. Warren MD & Ingrid Catz MD––Multiple Sclerosis Patient Care and Research Clinic, University of Alberta, Edmonton, Canada
The symptoms of multiple sclerosis (MS) arise due to sites of demyelination, called MS lesions, where electrical signals “short out” across lines of communication. Where in the brain these lesions form does not always determine what symptoms a patient will experience. The cerebellum is one common area in the CNS where we see lesions develop, and with it comes a unique set of symptoms that are at times difficult to treat.
The cerebellum, Latin for “little brain,” sits in the back of the brain atop the spinal cord. It functions in coordination, balance, and motor memory. The cerebellum also ensures that perceptual, motor, and cognitive functions are working correctly by acting as an “editor” of performance. Hand-eye coordination is a primary example of function orchestrated by the cerebellum (Campbell, 2002).
When MS lesions form in the cerebellum, patients start to experience significant loss of coordination of these functions. The major symptoms of MS cerebellar attack can be broken down into the following four areas: ataxia (both limb and gait), nystagmus, disequilibrium, and hypotonia.
A direct result of lesions in the cerebellum, ataxia refers to balance problems and uncoordinated muscle movement. The person sways and may appear to have a drunken swagger. Ataxia can affect arms, legs, and gait. Limb ataxia causes tremors that make a simple task like shaking someone’s hand or holding utensils very difficult, and in some cases the person may not even know where their hands are if they can not see them. According to the National Multiple Sclerosis Society, limb ataxia results from disruption of sensory signals regarding the position of joints and length of the muscles. Gait ataxia, on the other hand, results from a loss of balance regulation in the cerebellum. Despite the source, ataxia can disrupt both walking and completion of activities for daily living (ADLs). The use of a walker may mitigate mild ataxia; severe ataxia, however, often results in the use of a wheelchair. This can be the most functionally disabling of the MS symptoms, and unfortunately, often the most difficult to treat (http://www.nationalmssociety.org/about-multiple-sclerosis/symptoms/walking-gait-problems/index.aspx).
Another common symptom resulting from cerebellar lesions, nystagmus is the involuntary vertical or horizontal movement of the eye. Mild forms of nystagmus are common, and triggered only when patients look from side to side. These oscillations do not cause significant functional impairment; however, vision problems from optic neuritis or eye movement problems commonly found in MS can be an added and compounding issue that with nystagmus may make it difficult for a person to track and focus enough to read. Besides the problems caused by reduced vision regarding ADLs, vision impairment also contributes to symptoms of ataxia (http://www.nationalmssociety.org/about-multiple-sclerosis/symptoms/visualSymptoms/index.aspx).
Patients may also experience disequilibrium, or loss of balance, resulting in dizziness and vertigo. The cerebellum interprets spatial information that, when compromised, leads to a loss of perception to the surrounding environment. This often leaves the patient with balance disturbances and lightheadedness. These symptoms add to resultant walking problems associated with ataxia. Consequently, the patient may need assistive devices to maintain independence.
The patient with MS may also experience hypotonia, or decreased muscle tone. Muscle tone refers to the resistance to movement present in resting muscle. It may help to think of the “firmness” present in a muscle when it’s not in use. Hypotonia is different from weakened muscle. According to the National Institute of Neurological Disorders and Stroke, a patient with hypotonia may exhibit a “floppy” or “ragdoll” appearance. Hypotonia can affect walking and other activities when muscles become slack. Some describe the affected muscles as turning into “wet noodles,” which can make everything from standing to sitting upright extremely difficult (http://www.ninds.nih.gov/disorders/hypotonia/hypotonia.htm).
Symptoms of cerebellar MS are often severely disabling. Unfortunately, available treatment options of cerebellar tremors, ataxias, and disequilibrium are generally of limited value. We will briefly discuss available treatment options.
Although useful for the management of spasticity and catatonic symptoms associated with MS, benzodiazepines demonstrate little effectiveness for the management of tremors and ataxias. The unwelcome sedative effect will often outweigh any positive relief (Schapiro, 2003).
Deep Brain Stimulation
Some apparent value has been established for the treatment of cerebellar tremor using deep brain stimulation (DBS). The resolution of MS tremors appears to be less significant and more transient than DBS treatment for other sources of tremor. More research is necessary to understand if this approach is beneficial (Lyons & Pahwa, 2008; Yap, Kouyialis, & Varma ,2007).
Exercise is a standard and effective treatment for balance and coordination deficiencies. One such technique, called patterning, entails repeating a basic movement in order to train the nervous circuit used in the movement. The therapist aids at first, then adds resistance, and eventually, the patient retrains the circuit to a functional level. Therapists also use vestibular stimulation to improve balance, a technique that increases the activity in balance centers of the brain stem. By rocking, swinging, and spinning, the patient exercises and improves his or her balancing ability. The Swiss ball and balance stimulation can be useful in this regard (Schapiro, 2003).
By weighting parts of the upper extremities, patients may experience mild relief of tremors and increased control of muscles. The purpose is to engage more muscles involved in stabilizing the object by making the object heavier. This technique may be counterproductive, however, and decrease control of the object (Schapiro, 2003).
Medications that have been used in essential tremor, such as propranolol (Inderal®) and primidone (Mysoline®) have shown limited benefit with cerebellar symptoms. Recently levetiracetam has been studied in MS-related cerebellar symptoms, however no clinical benefit was observed (Solaro et al., 2008).
Unfortunately symptom-related to cerebellar MS are both disabling and quite resistant to treatment. More research is needed to determine if technologically-advanced options, such as deep brain stimulation, are of benefit
A Case Study: Progressive Loss of the Ability to Stand and Walk
At age 27, a Canadian male developed numbness of his right hand and lost his ability to write. After 10 months he learned to write with his left hand. Cutaneous sensation was reduced in the right hand, vibration sense was absent and proprioception of all fingers was reduced. At this time, tests of balance, stance, and gait were normal. There were no signs of weakness or spasticity in the right arm. MRI of the brain illustrated lesions characteristic of MS.
During the next 2 to 4 years the patient developed progressive difficulty with standing and walking, his gait was broad-based and spastic weakness with hyper-reflexia had developed in his legs. Although the patient required a wheeled walker for long distances, at this point in his illness, he was able to work in a grocery store. During the subsequent year walking became more impaired with poor balance and a wide-based gait.
Eight years from the disease onset, spastic weakness of the legs was permanent and cerebellar features of ataxic leg movements and a broad based gait were more pronounced. Severe gait dysequilibrium resulted in very poor standing balance. In order to walk around his house the patient had to hang on to furniture or walls. This case illustrates that within 10 years from the disease onset, this patient was unable to stand and walk due to cerebellar disease, but he retained function of his upper extremities, which makes this case unique as typically arms are also involved.
Campbell, A., & Reece, B. Biology, 6th Edition. San Francisco: Benjamin Cummings, 2002, pg. 1045.
Hypotonia Information Page, National Institute of Neurological Disorders and Stroke, National Institutes of Health (2007). Retrieved 10.24.2008 from: http://www.ninds.nih.gov/disorders/hypotonia/hypotonia.htm
Lyons, K. E. & Pahwa, R. (2008). Deep brain stimulation and tremor. Neurotherapeutics, 5(2), 331-8.
National Multiple Sclerosis Society (2008). Retrieved 10.24.2008 from: http://www.nationalmssociety.org/about-multiple-sclerosis/symptoms/index.aspx
Schapiro, T. (2003). Tremor and Balance in Managing the Symptoms of Multiple Sclerosis, 4th Ed., Chapter 6. New York: Demos; pp. 46-51.
Solaro, C., Brichetto, G., Capello, E., Abuarqub, S., & Sanguineti, V. (2008) Activity, tolerability and efficacy of levetiracetam on cerebellar symptoms in multiple sclerosis patients: A pilot kinematic study. European Journal of Neurology, 15(6), 619-26.
Yap L, Kouyialis A, & Varma T. R. (2007). Stereotactic neurosurgery for disabling tremor in multiple sclerosis: Thalamotomy or deep brain stimulation? British Journal of Neurosurgery, 21(4), 349-54.