2012年3月14日 星期三

Neurological Examinations - Ophthalmoscopy (Funduscopy) and Examination of the Motor System


Ophthalmoscopy (funduscopy): Direct examination of the Optic disc and retina with an Ophthalmoscope is an important step in the neurological examination. This requires considerable training and has to be practiced well.

Motor system: The muscle groups have to be examined with a view to elicit the following points:

Muscle bulk, tone, muscle strength, fasciculations, presence of involuntary movements, tendon reflexes, co-ordination and Gait.

In assessing these parameters it is important that the professional has an idea of the normal bulk and strength of the different muscles in relation to the general build and age of the individual. Muscle strength has been graded as follows:

Grade 0: Complete paralysis

Grade 1: Only a flicker of contraction is present.

Grade 2: Patient can manipulate the limb when gravity is eliminated by suitable positioning.

Grade 3: Limb can be moved against gravity, but not against further resistance.

Grade 4: There is some degree of weakness ranging from poor, fair or moderate strength.

Grade 5: Normal power is present.

Neurological motor disability may take several patterns.

Hemiplegia: Paralysis of both the limbs of one side or the body with also paralysis of the face in most cases; this results from unilateral lesions of the pyramidal tract above the brain stem.

Crossed Hemiplegia: Lower motor neuron paralysis of cranial nerves on one side and hemiplegia on the opposite side, this results from lesions in the brainstem.

Paraplegia: Paralysis of both lower limbs.

Monoplegia: Paralysis of only one limb.

Quadriplegia: Paralysis of all four limbs.

Tendon reflexes

The tendon reflexes are monosynaptic reflexes. Sudden strike on a lightly stretched muscle tendon evokes a sharp contraction. Elicitation of these reflexes gives valuable clues about the corresponding motor units regarding the integrity of the afferent and efferent pathways and excitability of the anterior pathways and excitability of the anterior horn cells. Several reflexes are made use of in clinical examination. The fact that the motor units subserving tendon reflexes are located in different levels in the spinal cord and brainstem has been made use of to determine the level of neurological lesion. From above downwards, these are:

1. Jaw jerk: Trigeminal nuclei in the Pons

2. Biceps Jerk: C5 and 6 segments

3. Triceps Jerk: C6, C7 segments

4. Supinator jerk: C5, C6 segments

5. Knee Jerk: L2, 3 and 4 segments

6. Ankle Jerk: S1 and 2 segments.

Tendon jerks may be absent, normal or exaggerated (very brisk). Very brisk tendon jerks may be accompanied by clonus.

Superficial reflexes

Several superficial reflexes can be elicited by appropriate stimuli. These are also altered in upper and lower motor neuron lesions. These also help in establishing the location of neurological lesion.

1. Abdominal reflexes: 7th to 12th thoracic segments of spinal cord

2. Cremasteric: L1 and L2 of the Lumbar segments of spinal cord

3. Scapular: C5 to T1

4. Anal: S3 and S4

5. Bulbocavernous: S3 and S4

6. Plantar: S1 and S2.

Coordination

This term implies the smooth recruitment, interaction and cooperation of separate groups of muscles, which result in a smooth and definite motor act. Incoordination results in imperfect performance of the motor act and leads to ataxia. Coordination is effected by several factors such as afferent propioceptive impulses from muscles spindles and joint receptors, cerebellar function and muscle tone. Ataxia may be due to loss of proprioceptive sensations or diseases of the cerebellum. In the case of sensory ataxia (eg, tabes dorsalis), visual impulses can compensate to maintain posture and movement so that with eyes open, the patient is able to maintain posture, but with eyes closed, ataxia manifests. Ataxia occurring in cerebellar disease is not influenced by visual impulses.

Gait

Analysis of the gait gives valuable neurological information. Well-defined neurological disorders give rise to characteristic gaits.

1. Spastic gait: Indicates pyramidal tract lesions such as spastic paraplegia or hemiplegia.

2. Stamping gait: This occurs in sensory ataxia in which the patient stamps his foot on the ground with the heel touching first. This gait is seen in posterior column lesions.

3. Cerebellar gait: This is described as the reeling or drunken gait.

4. Festinant gait: It is seen in florid parkinsonism.

5. Waddling gait: It resembles the git of a duck. This results from defects in maintaining posture due to weakness of the truncal and gluteal muscles. This is seen in myopathies. A similar gait may occur in bilaterla disease of the hip joints as well.

6. High stepping gait: In the patient lifts up his fet high to avoid tripping from the toes touching the ground. This type of gait is seen in patients with foot drop, eg, peripheral neuropathy.

Sensory examination

Proper results are obtained only when the patient is alert and cooperative. Considerable skill is required to elicit the sensations properly without unduly tiring out the patient. When testing the sensation, it is better to proceed from the abnormal to the normal area. The primary modalities that are tested include:

1. Tactile sensibility, including light touch, pressure, tactile localization and discrimination:

2. Pain-superficial and deep;

3. Temperature (heat and cold);

4. Position sense and appreciation of passive movement.

5. Vibration; and

6. Stereognosis- recognition of size, shape, weight, texture and form of objects.

Recording of neurological findings

The findings elicited on clinical examination should be systematically recorded. Many neurological disorders progress or resolve within short periods. Therefore the examination may have to be respected at regular intervals depending on the type of the disorder. This is all the more important in conditions such as transient ischemic attacks (TIAs), head injury, and meningitis.




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