Movement Disorders / Gait Ataxia
Ataxia is fundamentally a disturbance of muscle incoordination, which is not the result of muscle weakness or loss of muscle tone, or the intrusion of abnormal muscle movements. Implicit in the definition of ataxia is the presumption that muscle strength is not impaired, or not sufficiently impaired, to cause muscle incoordination. Those with ataxia have problems with the accuracy and organization of voluntary muscle actions, resulting in uncoordinated movements involving the trunk and/or limbs. The incoordination consists of irregularities in the rhythm, rate, and amplitude of voluntary movements causing voluntary movements to become jerky and erratic.

Plaques or scarring in the cerebellum, brain stem, basal ganglia or in other regions of the brain under the cerebral cortex (subcortical regions) are cause for multiple sclerosis (MS) movement disorders.

Cerebellar gait disturbances involve disturbances in stance and gait. Ataxia may primarily involve the trunk (truncal ataxia) and the patient may not be able to sit or stand unsupported (astasia); truncal ataxia is usually due to midline cerebellar disease, and associated limb ataxia due to lateral cerebellar hemisphere disease may not be present. Incoordination of walking (gait ataxia) that is so severe that the patient can't walk is called abasia, and the term astasia-abasia is used if the the patient's balance is so impaired that the patient can't maintain his balance when either sitting or walking. Persistent incoordination of the truncal axial musculature may produce body tilts, pelvic tilts or head tilts.

For many movement disorders, when muscles are taut, they tend to have abnormally increased tone. In MS, this can be due to motor tract damage or an upper motor neuron lesion. This can lead to a "scissoring gait" seen in MS patients' knees and thighs crossing in succession like the opening and closing of scissors.

Walking alone is a complex set of movements. There are so many things that can go wrong like one's standing balance can be lost, step alignment can be impaired, and sideways or back and forth rocking can impair the gait's rhythm. Demyelination of tracts that are involved with muscle tone lead to the scissoring described above. Weakness of muscles can complicate all of the involuntary and voluntary defects in muscle movement, impairing gait even more.

Absence of movement (akinesia or freezing), slow movement (bradykinesia), rest tremor, rigidity like all aspects of Parkinson's Disease (PD), can also intrude into the array of abnormal movement in MS, not typically as an added disease such as PD, but as a problem within the MS spectrum of movement disorders.

Most movement disorders in MS and in general disappear during sleep. One exception, sometimes associated with MS is Restless Leg Syndrome, and also Periodic Leg Movements. This condition can disrupt sleep due to the awakening effect of leg thrusts and lead to daytime fatigue.

Primary-Progressive Multiple Sclerosis (PPMS)

The vast majority of patients who end up diagnosed with primary-progressive multiple sclerosis (PPMS) begin noticing that they are having problems walking, which gradually gets worse. However, the first symptoms of some people with PPMS are slowly worsening tremor and problems with balance.

One of the presentations of PPMS is a worsening ability to walk. This is by far the most common presentation of symptoms for PPMS, with as many as 80 to 85% of patients experiencing these symptoms. Also called progressive myelopathy, these symptoms consist of:

Severe intention tremor, the inability to perform small movements accurately due to shaking or trembling hands.

Hypotonia, a loss of muscle tone.

Dysmetria, the lack of ability to coordinate movements, which is exhibited by the person "overshooting" (hypermetria) or "undershooting" (hypometria) the intended position of the hand, arm or leg.

Dysdiachokinesia, which is the inability to perform rapid, alternating movements.

An increasingly spastic gait (spastic paraparesis), with the legs stiffening up to cause a limp and/or rhythmic jerkiness.

Spastic hemiparesis, where there is weakness or inability to move on one side of the body (arms or legs) and/or an inability to hold things on that side.

Gait ataxia, a staggering way of walking.

Clumsiness, stiffness, dragging legs.

Exercise-related fatigue, meaning people are not able to walk far without resting.

Stumbling and falling.

In patients that have these types of symptoms, the magnetic resonance imaging (MRI) scans of their brains show few (if any) lesions and few gadolinium-enhancing lesions. However, an MRI scan of their spines will often show a atrophy, which is a result of axon and oligodenrocyte cell loss and injury.
Gait
Many people with MS will experience difficulty with walking, which is more formally termed gait. Studies suggest that half the people with relapsing-remitting multiple sclerosis (RRMS) will need some assistance with walking within 15 years of their diagnosis. Gait problems in MS are caused by a variety of factors such as fatigue. MS damage to nerve pathways may hamper coordination and/or cause weakness, poor balance, numbness, or spasticity. Concern about falling and the emotional impact of appearing impaired in public causes problems as well.

Muscle weakness clearly interferes with walking. Damage to neurons (nerve cells) can affect a particular muscle group or groups so they no longer respond to the nervous system input that normally guides the act of walking. Muscle weakness that interferes with walking is not the same thing as MS fatigue. But MS fatigue can make walking problems worse. Since fatigue is so common in MS, an assessment will include exploration of these problems too-and you may be advised to use a mobility aid to manage fatigue and muscle weakness.

Many people continue to walk, and to work on improving their walking while using an aid. They find that assistive devices allow them to get where they want to go without exhausting all their energy reserves. The idea is not appealing initially to many people because a cane typically represents "feebleness" and a wheelchair or scooter says that MS has "won." The majority of people with MS who use the right assistive technology end up with a very different perspective. They recognize that a brace or cane allows them to walk with confidence and a wheelchair or scooter provides safety, speed, and saves energy for more important things.

At present, people with MS gait problems remain mobile and independent through physical therapy, exercise, medication, and assistive technology. New ways to prevent permanent losses and to improve the technology that compensates for losses are in development.

There are many different types of "gait" associated with MS and many other illnesses. The similarity in them all is the fact that they all can cause a degree of difficulty in walking, to what degree depends on the illness, severity, and location.

Types of Gait Associated with MS:
Sensor ataxic An irregular, uncertain, stamping gait. Legs are kept far apart, and either the ground or the feet are watched, because there has been a loss of knowledge of the position of the lower limbs. This gait is caused by an interruption of the afferent nerve fibers.
Scissor Legs flexed slightly at the hips and knees, giving the appearance of crouching, with the knees and thighs hitting or crossing in a scissors-like movement.
Spastic Slow, shuffling gait in which the patient appears to be wading in water. Knee and hip movements are restricted. Also referred to as creeping palsy.
Steppage During footdrop in which the advancing leg is lifted high so that the toes can clear the ground.

Other types of gait include:
Antalgic A limp adopted so as to avoid pain on weight-bearing structures, characterized by a very short stance phase.
Ataxic Unsteady, uncoordinated walk, employing a wide base and the feet thrown out.
Cerebellar Unsteady, irregular gait characterized by short steps and a lurching from one side to the other.
Double-step Noticeable difference in the length or timing of alternate steps.
Festinating Characterized by rigidity, shuffling, and involuntary hastening. The upper part of the body advances ahead of the lower part. It's associated with paralysis agitans and postencephalitic Parkinson's syndrome.
Helicopod The feet describe half circles, as in some conversion disorders.
Hip extensor A gait in which the heel strike is followed by throwing forward of the hip and throwing backward of the trunk and pelvis.
Myopathic Exaggerated alternation of lateral trunk movements with an exaggerated elevation of the hip.
Quadriceps Each step on the affected leg the knee hyperextends and the trunk lurches forward.
Propulsive A stooped, rigid posture, with the head and neck bent forward.
Staggering A reeling, tottering, and tipping gait in which the individual appears as if he may fall backward or lose his balance. It's associated with alcohol and barbiturate intoxication.
Stuttering One characterized by hesitancy that resembles stuttering.
Waddling An exaggerated alteration of lateral trunk movements, with an exaggerated elevation of the hip, suggesting the gait of a duck; characteristic of progressive muscular dystrophy.
Foot Drop and Steppage Gait
Foot drop is an abnormal neuromuscular (nerve and muscle) disorder causing weakness or paralysis and subsequently the inability to raise the front part of the foot. As a result, individuals with foot drop scuff their toes along the ground or bend their knees to lift their foot higher than usual to avoid the scuffing, which causes what is called a steppage gait or footdrop gait. Foot drop can be unilateral (affecting one foot) or bilateral (affecting both feet). Foot drop is a symptom of an underlying problem and is either temporary or permanent, depending on the cause.

Foot drop is further characterized by an inability to point the toes toward the body (dorsiflexion) or move the foot at the ankle inward or outward. Pain, weakness, and numbness may accompany loss of function. Walking becomes a challenge due to your inability to control the foot at the ankle. The foot may appear floppy and you may drag the foot and toes while walking.

In MS, foot drop occurs because the message from the brain to "lift" doesn't make it all the way to the foot. The foot itself is just fine, it's just waiting for instruction. A simple way to check for any abnormal foot placement during walking is to look at the bottoms of your shoes for any abnormal wear patterns such as the front tip being worn down or scuffed.
Diagnosing Gait Disorders
A person's manner of walking or gait can reveal disturbances involving motor, sensory, visual, vestibular, cerebellar, cognitive, psychological and musculoskeletal systems. For example, people in the later stages of Alzheimer's often have "reduced gait," meaning their ability to lift their feet as they walk has diminished.

To diagnose a gait disorder, your neurologist should review your medical history and perform a complete physical and neurological examination that will include an evaluation of your gait. They should have you to walk in a corridor or climb stairs to observe specific features of your walk including:
Stance, posture, and base (wide or narrow)
Gait initiation (including start hesitation or freezing)
Walking speed, stride length, step height, foot clearance
Continuity, symmetry, or path deviation
Trunk sway or arm swing
Involuntary movements (e.g., tremor, chorea, dystonia)
Ability to turn
Ability to walk on heels and toes and squat
Ability to rise from a chair (without using the arms)