Chapter 15 - Evaluation of the Ataxic Patient
Questions
Define the following terms:
Ataxia, dysequilibrium, sensory ataxia, astasia-abasia, gait apraxia.
Ataxia is a generic term for inability to coordinate movement. It is often applied to imbalance of gait.
Dysequilibrium is a loss of stability (equilibrium) usually due to problems with sensory systems although also occurring with disorders of the extrapyramidal or cerebellar motor systems.
Sensory ataxia is the impairment of proprioceptive functions, leading to instability of gait. The sensory systems that are used to control balance are the prorioceptive nerve fibers from the lower limbs, the inner ear vestibular organ and visual input.
Astasia-abasia is a dramatic lurching when standing or walking that appears to preclude safe ambulation. However, the patient catches him/herself and only falls in safe places (into an examiner's arms or onto a couch, for example). This is considered to be a sign suggesting that the problem is not with motor or sensory function but is likely to be related to a hysterical presentation.
Gait apraxia is a condition in which the patient makes very simple movements while walking, usually sliding his/her feet along the ground in a "robotic" or "glue-footed" manner. This is due to dysfunction of the frontal lobes and the patient often becomes retropulsive (pushing over backwards) when it is most severe.
15-1. What systems are important to normal, safe ambulation?
15-1. There are sensory and motor systems that are important. On the sensory side, vision, somatic sensation (conscious proprioception) from the feet and the vestibular system are important. On the motor side, adequate strength (upper and lower motor neurons), cerebellar systems and extrapyramidal systems are employed in ambulation. The frontal lobes of the cerebral cortex are also involved in normal gait.
15-2. What gait disturbance is seen with pain?
15-2. Patients limp in order to protect an injured area.
15-3. What kind of gait disturbance would you expect to see in the patient with dysfunction of conscious proprioception (either a large fiber polyneuropathy or dorsal column damage)?
15-3. They experience disequilibrium. The patient has a wide based gait and they often look at their feet while walking. They have many more problems walking in the dark and on irregular ground and usually have a very noticeable Romberg sign. Their imbalance improves dramatically by touching a stationary object.
15-4. What symptoms would suggest vestibular abnormality as the cause of ataxia?
15-4. Patients with vestibular problems are usually vertiginous and nystagmus may be seen on examination. They will usually tend to veer or deviate toward one side when walking, especially if their eyes are closed or if they are asked to walk tandem.
15-5. What symptoms would suggest cerebellar abnormality as the cause of ataxia?
15-5. Patients with cerebellar ataxia often have trunkal ataxia and other signs of cerebellar disease, such as speech disturbance or limb incoordination. Their gait tends to be a reeling or drunken type of gait and they have trouble standing with the feet together regardless of whether their eyes are open or closed.
15-6. What role does strength play in gait?
15-6. Of course, strength is necessary to be able to stand and walk. There are some specific gaits: the waddling gait of hip girdle weakness; the steppage gait of foot-drop; the swinging gait of quadriceps weakness; and the circumducting or scissors gait of upper motor neuron weakness. An important question is whether the degree of their ataxia explained by their weakness. If weakness is a significant problem, then the investigation of weakness should proceed as in chapter 12.
15-7. What symptoms would suggest extrapyramidal abnormality as the cause of ataxia?
15-7. The most common extrapyramidal disorder is Parkinson disease, although there are a large number of other, rare conditions that cause “parkinsonism.” Most of these conditions produce a type of increased tone called rigidity, and postural reactions are often slowed or delayed. Postural corrections (reactions) can be tested by standing behind the patient and then attempting to pull them over suddenly (of course, you must be prepared to catch them). Other clues to abnormal extrapyramidal function include abnormal movements at rest and slowed eye movements (some conditions prevent voluntary vertical eye movements). Some involuntary movements, such as myoclonus, chorea or asterixis can introduce abnormalities in gait.
15-8. What symptoms would suggest frontal lobe disease or degeneration as the cause of ataxia?
15-8. The classic gait of frontal lobe disease is “apraxia.” This consists of a gait in which the person slides their feet along the floor (“magnetic” or “glue-footed”). They are likely to have signs of personality change or cognitive change (the latter especially if the frontal lobe dysfunction is part of a more generalized cortical dysfunction). Frontal lobe dysfunction often leads to incontinence of a curious type where there is little or no warning.
15-9. What symptoms would suggest frontal lobe disease or degeneration as the cause of ataxia?
15-9. The classic gait of frontal lobe disease is “apraxia.” This consists of a gait in which the person slides their feet along the floor (“magnetic” or “glue-footed”). They are likely to have signs of personality change or cognitive change (the latter especially if the frontal lobe dysfunction is part of a more generalized cortical dysfunction). Frontal lobe dysfunction often leads to incontinence of a curious type where there is little or no warning.
15-10. How can you determine if a gait disturbance is real?
15-10. This is an important question since “inability to walk” can be hysterical. There are several important questions to ask when examining the patient. Is the gait disturbance consistent with known patterns of difficulty? Have others noticed it? Does it affect functioning in the way and to the degree that you would expect given the complaints? Has it resulted in falls? Does the patient manifest astasia-abasia (severe lurching, but catching themselves prior to injury) that would suggest substantially higher function than they are manifesting?