Showing posts with label Neurology. Show all posts
Showing posts with label Neurology. Show all posts

Sunday, October 28, 2012

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Ataxic gait

This type of gait can be seen in cases of cerebellar or sensory ataxia.

Cerebellar ataxia and gait:

The problem here lies with the coordinating mechanisms in the cerebellum and its connecting systems. The gait is a clumsy, staggering, unsteady, irregular, lurching, titubating and wide-based. The patient may sway to either side, back or forward. Leg movements are erratic, and step length varies unpredictably.
The patient is unable to follow a straight line on the floor (to walk tandem).

With a lesion of the cerebellar vermis, the patient will exhibit a lurching, staggering gait but without laterality, the ataxia will be as marked toward one side as the other.
Cerebellar ataxia is present with eyes both open and closed; it may increase slightly with eyes closed but not so markedly as in sensory ataxia.

A gait resembling cerebellar ataxia is seen in acute alcohol intoxication.

With a hemispheric lesion the patient will stagger and deviate toward the involved side. In disease localized to one cerebellar hemisphere or in unilateral vestibular disease, there is persistent swaying or deviation toward the abnormal side. As the patient attempts to walk a straight line or to walk tandem he deviates toward the side of the lesion.
A patient with acute vestibulopathy will drift toward the involved side walking forward, and continue to drift during the backward phase. The resulting path traces out a multipointed star pattern. Walking a few steps backward and forward with eyes closed may bring out “compass deviation” or a “star-shaped gait”.
When attempting to walk a fixed circle around a chair, clockwise then counterclockwise, the patient will tend to fall toward the chair if it is on the side of the lesion, or to spiral out away from the chair if on the opposite side.

Either unilateral cerebellar or vestibular disease may cause turning toward the side of the lesion on the Fukuda stepping test. For all the tests that bring out deviation in one direction, other findings must be used to differentiate between vestibulopathy and a cerebellar hemispheric lesion. Unilateral ataxia may be demonstrated by having the patient attempt to jump on one foot, with the eyes either open or closed. The patient with bilateral vestibular disease may seek to minimize head movement during walking, holding the head stiff and rigid; having the patient turn the head back and forth during walking may bring out ataxia.

Sensory ataxia and gait:

The patient in this condition is extremely dependent on visual input for coordination. When deprived of visual input, as with eyes closed or in the dark, the gait deteriorates markedly. The difference in walking ability with and without visual input is the key feature of sensory ataxia. If the condition is mild, locomotion may appear normal when the patient walks eyes open. More commonly it is wide based, and poorly coordinated.

The term “steppage gait” refers to a manner of walking in which the patient takes unusually high steps. Sensory ataxia is one of the causes of a steppage gait. The patient takes a high step, throws out her foot and slams it down on the floor in order to increase the proprioceptive feedback. The heel may land before the toe, creating an audible “double tap.” An additional sound effect may be the tapping of a cane, creating a “slam,slam, tap” cadence. The sound effects may be so characteristic that the trained observer can make the diagnosis by listening to the footfalls.

The patient with sensory ataxia watches her feet and keeps her eyes on the floor while walking. With eyes closed, the feet seem to shoot out, the staggering and unsteadiness are increased, and the patient may be unable to walk. There is less reeling and lurching in sensory ataxia than with a comparable degree of cerebellar ataxia. The difficulty is even worse walking backward, since the patient cannot see where she is going. The patient with bilateral foot drops, however, also has a steppage gait and a double tapping sound striking.

In all of these tests, sensory ataxia can be differentiated from predominantly cerebellar ataxia by accentuation of the difficulty with eyes closed; and unilateral cerebellar or vestibular disease from vermis involvement by laterality of unsteadiness.


Friday, July 6, 2012

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Ice water test - Traumatic spinal cord injury

This test was first described by Bors and Blinn in 1957. The authors did this test to check if there are any temperature receptors in the bladder, how they work and whether the test can have a diagnostic purpose.

Procedure: (originally done by Bors and Blinn)
60 mL of ice cold water is instilled in the bladder in 30 seconds and patient is requested to try to retain the fluid.

Results:
If water is expelled in less than 1 minute, the test is said to be positive.

Interpretation:
The rapid evacuation of the fluid is due to the reflex contraction of the detrusor muscle. The authors also found that this test was positive in patients having an upper motor neuron lesion.
The physiology behind is that there are cold receptors in the bladder wall. From there, the impulses travel through the afferent C fibers to the spinal cord and return via the motor nerves to the detrusor muscle thereby completing the reflex arc. This reflex is normally present in children up to the age of 4. After this age, it becomes inhibited centrally.

Saturday, January 28, 2012

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Romberg's test - how to do and interpretation

 INTRODUCTION 
Romberg's test is done to assess the integrity of the dorsal columns of the spinal cord.

It is not a test to assess the cerebellar function.

The test was first described by Moritz Heinrich von Romberg who found that patients with tabes dorsalis (neurosyphilis) often complained of increased unsteadiness in the dark.

The test should be performed in all patients who complain of dizziness, imbalance or falls to rule out sensory ataxia.


 HOW TO DO THE TEST? 
The test is done by requesting the patient to keep his feet firmly together, arms by the side and the eyes open at first. The balance of the patient is noted.
Now the patient is asked to close both eyes and the balance is now noted for around 1 minute. The physician should stand in front of the patient with his arms extended on either side of the patient but not touching him. This is done as the latter may fall.

 INTERPRETATION 
1) If with the eyes open, the balance is not good then there may be a problem with the cerebellum. This condition is called as cerebellar ataxia.
2) If closing the eyes causes a much worse balance then the test is said to be positive (Romberg test positive). It indicates that the patient is excessively reliant on his vision to maintain balance. The problem may lie in the vestibular or proprioceptive systems.

The physiology behind this test is that to maintain balance we need at least 2 of the following 3 components:
1) vision,
2) proprioception and
3) vestibular function.
In simple words. . .If a patient has a vestibular problem then with his eyes open he can maintain balance because his proprioception as well as vision is helping him. But now if he closes his eyes, then there is only proprioception to maintain balance and that is not sufficient. So the patient will sway and may fall.

The same is true for someone with a problem of proprioception. With his eyes open, the patient can maintain balance because he is using his normal vision and vestibular apparatus. But when he closes his eyes, he is only relying on his vestibular function now and thus he will sway and may fall.

 COMMON CAUSES OF POSITIVE ROMBERG TEST: 
1) Vitamin B12 deficiency - Subacute combined degeneration of the cord,
2) Diabetic peripheral large fibre neuropathy,
3) Friedrich's ataxia,
4) Tabes dorsalis.

 N.B 
1) The test may be positive in some patients who are having some motor disorders.
2) If the unsteadiness is due to anxiety then we can divert the patient's attention, e.g. by having him touch the index finger of each hand alternately to his nose while standing with eyes closed.
3) Patients with authentic proprioceptive problems will sway when their gaze is diverted from the ground and the situation worsens when the eyes are closed.
4) Patients with factitious unsteadiness, usually will remain stable when their gaze is diverted from the ground e.g. if they are looking at the ceiling or a distant object and then become very unsteady when the eyes are closed.

Last reviewed on : 1 September 2015