METHODS OF PHYSICAL EXAMINATION OF CNS SENSORY NERVOUS SYSTEM

METHODS OF PHYSICAL EXAMINATION OF SENSORY NERVOUS SYSTEM PRESENTED BY Dr. LALRAVI SAHU Ist YEAR PG SCHOLAR DEPARTMENT OF PANCHKARMA ,SDMCAH HASSSAN 1

CONTENTSINTRODUCTIONSENSORY NERVOUS SYSTEM EXAMINATIONNEURAL PATHWAYSLATERAL SPINOTHALAMIC TRACKPOSTERIOR COLUMNASSESMENTEXAMINATION SEQUENCEDISCUSSION

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INTRODUCTIONNervous system controls all the activities of body. It is quicker than all the other systems in the body. Primarily Nervous system is divided into two parts- 1.CENTRAL NERVOUS SYSTEM AND 2. PERIPHERAL NERVOUS SYSTEM

The central nervous system includes brain and spinal cord. Brain is situated in skull and it is continued to vertebral column through the foramen magnum. 3

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Cont...A sensory system is a part of nervous system responsible for processing sensory information.

Sensory system consist of sensory receptors, neural pathways and part of brain involved in sensory perception.4

SENSORY NERVOUS SYSTEM EXAMINATIONFor sensory nervous system examination one should aware:Dermatone. Peripheral nerve distribution.

This knowledge is necessary to appreciate that a certain distribution of abnormal sensation results from a lesion of particular peripheral nerve, nerve root or spinal segment level.5

DERMATONE...

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NEURAL PATHWAYSSensory impulses travel to the brain via Two ascending neural pathwaysSpinothalamic tractPosterior columns

Impulses originate in the afferent fibers of the peripheral nerves, are carried through the posterior dorsal root into the spinal cord.

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LATERAL SPINOTHALAMIC TRACT8

POSTERIOR COLUMN9

ASSESSMENTScatter stimuli over the distal and proximal parts of all extremities and trunk to cover most of the dermatomes.Abnormal symptoms may indicate need to test the entire body surfacePainNumbnessTingling

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Compare sensations on symmetric parts of the body.

If decrease in sensationSystematic testingFrom point of decreased sensation toward sensitive areaNote where sensation changes

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EXAMINATION SEQUENCELIGHT TOUCH

DEEP PAIN

TEMPERATURE

VIBRATION

JOINT POSITION SENSE

TWO POINT DISCRIMINATION

POINT LOCALISATION

STEREOGNOSIS AND GRAPHAESTHESIA

SENSORY IN ATTENTION

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LIGHT TOUCHWhile patient looks away or closes his eyes, use a wisp of cotton wool and ask the patient to reply to each touch. Normal Findings-if patient Correctly identifies light Touch then it Is normal. Abnormal findings are found in :- Peripheral neuropathies due toDiabetesFolic acid deficiencies

Lesions of the ascending spinal cord, brain stem, cranial nerves, and cerebral cortex

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SUPERFICIAL PAINUse fresh neurologic pin .Do not use hypodermic needle.

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DEEP PAINSqueeze the muscle bellies E.g. Calf , biceps, apply pressure to fingernail or toenail beds .Do not apply pressure with an instrument.15

Cont....Abnormalites of pain- Analgesia = absence of pain sensation Hypoalgesia = pain sensation decreased Hyperalgesia = pain sensation increased

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TEMPERATURETouch the patient with a cold metallic object e.g. tuning fork and ask if he feels cold.More sensitive assessment requires test tubes of hot and cold water at controlled temperature.17

VIBRATIONPlace a 128Hz tuning fork over the over the sternum.Next place it on the tip of great toe. If sensation is impaired, place the fork on the interphalangeal joint and progress proximally-the medial melleolus, tibial tuberosity and anterior illiac spine-depending upon the response.18

Vibration often first sense to be lost in peripheral neuropathy.

Loss of vibration means- posterior column disease or lesion of peripheral nerve or root.

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JOINT POSITION SENSERepeat this process in upper limb. Start at the distal interphalangeal joint of the forefinger, and if sensation is impaired ,proceed proximally-radial styloid olecranon ,acromion.

If in doubt as to the accuracy of the response, ask the patient to close his eyes and report when you stop the fork vibrating with your finger.20

TWO POINT DISCRIMINATIONUse a two point discriminator or an opened out paper clip.Ask patient to look away or close eyes.Apply either one or two point to the pulp of the patient fore finger and ask whether one or two stimuli were felt.Adjust the difference between the two points to determine the minimum separation at which they are felt separately. Test on both the fingers and thumb.21

POINT LOCALISATIONWith the patient eyes closed lightly touch various body parts like hand, finger solder; and ask which part has been touched and whether on right or left.Repeat touching individual fingers and ask patient to identify which is touched. Inability to do so is finger ignosia.22

STEREOGNOSIS AND GRAPHSTHESIAAsk the patient to close his eyes .place a similar object like coin , key matchstick, in the patients hand and ask him/her to identify what they are after feeling them. (stereognosis)

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Cont...Use a blunt end of pencil or orange stick and trace letters or digits on patients palm. ask the patient to identify the figure. (graphaesthesia)24

SENSORY INATTENTIONAsk the patient to close his eyes . touch the back of each of the patients hands in turn and ask whether the left ,right or both sides were touched.25

DISCUSSIONIf normalIdentifies light touch, dull and sharp sensations to trunk and extremities.Vibratory sensation, stereognosis, graphesthesia, two-point discrimination intact.Abnormal results in these tests indicate lesions of the sensory cortex.These tests not done on children 6 yrs and younger.

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Cont...65yrs &older loss of sensation of vibration at the anklePosition sense in big toe may be lostTactile sensation impaired27

SENSORY CHANGES IN VARIOUS DISEASESPolyneuropathy-symmetrical glove and stocking anesthesia involving all the modalities of sensation. There is calf tenderness.Cauda equina and conus lesion- loss all the modalities of sensations involving specially lower sacral segments leading to perianal anesthesia.

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Anterior spinal syndrome- loss of pain temperature and touch below a level on both side with preserved position, joint and vibration sense. E.g. anterior spinal artery thrombosis. Posterior spinal syndrome- loss of position, joint and vibration sense below a level with touch temperature and pain senses. E.g. tabes dorsalis.29

ContMultiple roots involvement there are varying degree of impairment of cutaneous of the nerve roots. Pain sensation is more affected than touch.

Complete section of spinal cord- all forms of sensations are abolished below a particular level , with a narrow zone of hyperesthesia at the upper margin of the anaesthetic zone . In some patients with high cord compression saral fibre may be spared resulting in sacral spare.30

Brain stem syndrome- loss of touch , pain and temperature on same side of face and other side of body due to involvement of trigeminal track and nucleus and lateral spinothalamic tracts.

Thalamic syndrome-loss of all the modalities of sensation on opposite side of body. Position sense is more affected than any other sensation. 31

Cont.

Parietal lobe syndrome- there is loss of discriminative sensory function:Loss of tactile localizationLoss of tactile discriminationTactile extinctionAstereognosisPrimary modalities of sensation32

Hemisection of spinal cord- pain and temperature is lost a few segments below a particular level on the opposite site while vibration position and joint senses are affected on same side.

Syringomyelia loss of pain , temperature sensation. Touch vibration and position senses are normal and this is called as dissociate anaesthesia.33

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