The cerebellum controls and corrects all body movements so when there is damage there, it can result in poor balance or coordination. This can even cause difficulty grasping small objects, writing clearly, or keeping a steady hand. When walking across a room, it's not uncommon to lose your balance, as if you were drunk.
Balance & coordination problems can include:
•Loss of balance•Tremor•Unstable walking (ataxia)•Dizziness (vertigo)•Clumsiness of a limb•Lack of coordination•Weakness - primarily affecting the legs and walking
Ataxia is incoordination caused by dysfunction to sensory nerve inputs, motor nerve outputs, or the processing of them. It's not the result of muscular weakness. Ataxia is most often applied to unsteadiness in walking but it also refers to upper body incoordination and dysfunction in eye movements and speech.Ataxia is common in MS but is also seen in several other conditions including diabetic polyneuropathy, acute transverse myelitis, vacuolar myelopathy, tumor or cord compression and hereditary forms of ataxia.
There are three types of ataxia, all of which are seen in MS: Cerebellar, Vestibular, and Proprioceptive (Sensory).
Cerebellar Ataxia
Cerebellar ataxia indicates ataxia due to dysfunction of the cerebellum. This is caused by lesions in the cerebellum or in the parts of the brain that connect to it, such as the cerebellar peduncles, the pons or the red nucleus. This causes a variety of elementary neurological deficits, such as antagonist hypotonia, asynergy, dysmetria, dyschronometria, and dysdiadochokinesia. How and where these abnormalities manifest depend on which cerebellar structures are lesioned, and whether the lesion is bilateral or unilateral. Because the cerebellum is responsible for synchronizing voluntary muscle movement throughout the body, this can cause movement to become out-of-sync.
Cerebellar ataxia can result in:
•Gait ataxia - Uncoordinated walking•Nystagmus - Jittery eye movements•Hypotonia - Inability to maintain a steady posture•Dysdiadochokinesia - Inability to maintain a steady rhythm•Intention tremor - Shaking when attempting fine movements•Dysarthria - Inability to coordinate muscles involved in speech•Dysmetria - Reduced control of range of movement such as over or under-shooting targets
Vestibular Ataxia
Vestibular ataxia indicates ataxia due to dysfunction of the vestibular system, which in acute and unilateral cases is associated with prominent vertigo, nausea and vomiting. In slow-onset, chronic bilateral cases of vestibular dysfunction, these characteristic manifestations may be absent, and dysequilibrium may be the sole presentation.
In MS, vestibular ataxia is caused lesions to brainstem and the vestibular nuclei. In other conditions, it can also result from damage to the eighth cranial nerve leading from the balance organs in the inner ear.
Vestibular ataxia can result in:
•Loss of balance•Vertigo - Dizziness, nausea and vomiting•Nystagmus - Jittery eye movements
Sensory (Proprioceptive) Ataxia
Sensory ataxia indicates ataxia due to loss of proprioception (sensitivity to joint and body part position), which generally depends on dysfunction of the dorsal columns of the spinal cord, since they carry proprioceptive information up to the brain; in some cases, the cause may instead be dysfunction of the various brain parts that receive that information, including the cerebellum, thalamus, and parietal lobes.
Sensory ataxia presents with an unsteady "stomping" gait with heavy heel strikes, as well as postural instability that is characteristically worsened when the lack of proprioceptive input can't be compensated by visual input, such as in poorly lit environments. This results from dysfunction to position sensing (proprioceptive) nerve inputs. This means that the brain is confused as to the position of limbs.
Sensory ataxia results in:
•Loss of position sense - where hands and feet are•The inability to detect vibrations•Romberg's sign - An unstable stance
Gait and balance disturbances are common with MS. Balance problems without vertigo may be more constant, causing the person to sway or stagger. Balance problems may be the result of direct damage to the balance center of the brain, usually in the cerebellum or they can also be the result of other MS related problems such as visual disturbances, vertigo, dizziness, loss of sensation, spasticity of the muscles or muscle weakness.Dizziness describes the feeling of being lightheaded or feeling faint. Vertigo is the sensation of the person's surroundings spinning or the ground rushing towards them. In some cases, this can even cause the feeling of nausea, as if the person had motion sickness.
Vertigo is a fairly common symptom of MS and occurring in about 20% of people with MS at some point. It's an acute, uncomfortable sensation, making those affected by it a little unsteady and nervous regarding moving around. It's not a permanent symptom, and may not even indicate a new lesion or inflammation, as vertigo can have non-MS causes.
These symptoms are due to lesions in the complex pathways that coordinate visual, spatial, and other input to the brain needed to produce and maintain equilibrium.
Vertigo can be caused by lesions in the cerebellum. It can also be a result of damage to the nerves that control the vestibular functions of the ear (cranial nerve VIII) in the brain stem. However, it appears that a very common cause in people with MS is something called benign paroxysmal positioning vertigo (BPPV), rather than demyelination. This means that, just because you have MS, doesn't necessarily mean that the vertigo is a direct result of the MS disease process. BPPV can often be treated without medications and doesn't indicate a relapse or increased disease activity.
Vertigo can also be made worse by some of the drugs prescribed for MS symptoms, such as tricyclic antidepressants for neuropathic pain or Baclofen for spasticity, as these drugs can cause dizziness.
Common techniques to improve balance:Exercises and techniques designed to induce brief periods of loss of balance teaching you to adapt. Exercises may include eye or head movements, distorting or eliminating visual input, and changing or moving weight-bearing surfaces.
These may be as simple as using a handrail on the stairs or making sure you get adequate rest if you tend to lose your balance when you are tired. Major help can come from aids such as a cane, brace, or walker. These aids improve your personal appearance and increase safety, as balance problems can lead to slips and falls.
Spasticity or fatigue may indirectly affect balance. These conditions can be managed with medications in addition to physical and occupational therapy.
Testing Coordination, Balance, and Gait
Coordination and walking (gait) require integration of signals from sensory and motor nerves by the brain and spinal cord. To test these abilities, doctors ask a person to walk in a straight line, placing one foot in front of the other. They ask the person to use the forefinger to reach out and touch the doctor’s finger, then the person’s own nose, and then to repeat these actions rapidly. The person may be asked to do these actions first with the eyes open, then with the eyes closed.