Neurological Examination of the Upper Limbs

The general principles of neurological examination will be common to all parts of the body and a knowledge of anatomy is required to interpret findings. If the pathology can be explained by a lesion of a single nerve or group of nerves such as the brachial plexus, it would appear to be a peripheral nerve lesion. Otherwise, especially where motor and sensory signs appear to be independent, it is probably a lesion of the central nervous system. This includes the spinal cord. The segmental sensory innervation passes along the lateral aspect of the arm from C4 over the shoulder and up the medial side to T2 in the axilla. Motor supply simply moves distally from C4 in the deltoid down to T1 in the small muscles of the hand.

There is more than one way of performing a neurological examination and a clinician should develop his own technique. Poor technique will fail to elicit signs or will produce false results. In examinations such as MRCP, much emphasis is placed on correct performance of examination technique. The article on neurological history and examination covers many of the basic principles of examination and technique.

Examination of the upper limb may be performed with the patient sitting in a chair or standing rather than on the couch and this can be rather easier.

Note if there appears to be any damage to the hands. The mutilation associated with leprosy is caused not by the infection but by failure to respond to noxious stimuli. Pain is a protective mechanism.

Sensation

Light touch can be tested by using a light touch of the finger, a piece of cotton wool or a small brush. It is important to touch and not to stroke as moving sensation, such as rubbing and scratching are conducted along pain pathways.

Sharp sensation is often tested by using a disposable needle. An ordinary pin may be preferable as it is less likely to draw blood but a new pin must be used for each patient.

• A logical progression is required. A sensible progress would be to start testing over the shoulder and to move along the lateral aspect of the arm and up the medial side as this moves progressively from C4 to T2 dermatomes.
• The hand requires more intense testing. It may be useful to return to it after testing the rest of the arm.
• Some people would test first with sharp and then with light touch. A better technique may be to use both and to touch the patient with one or the other, saying to the patient, "When I touch you say sharp or soft."
• Test both the plantar and the dorsal surface of the hand.Test both the medial and lateral aspects of fingers and thumbs over the planar surface of the distal phalanx. Be aware of the distribution of the median, ulnar and radial nerves. Usually, on the plantar surface, the ulnar nerve supplies the thumb, index and middle fingers and the lateral aspect of the ring finger whilst the ulnar nerve supplies the medial aspect of the ring finger and the little finger. There is variation and sometimes the median nerve supplies all of the ring finger and sometimes none.
• Testing for temperature sensation is often overlooked but it can be important. Tubes of hot and cold water may be used but an easier and more practical approach is often to touch the patient with a tuning fork as the metal feels cold. First touch the patient where sensation is thought to be normal, such as the face and say, "Does that feel cold?" Then, when testing the limb, check that the patient is feeling the fork as cold and not just as pressure.

In most instances, where there is impairment of sensation over an area, there will be impairment of all modalities of sensation. A notable exception is syringomyelia.

Proprioception

• Proprioception is often tested just in the lower limb but it can be tested in the upper limb too. Take the hand and hold a finger between your index finger and thumb. Grasp the side of the finger so that movement is not felt as pressure up or down. Ask the patient to close his eyes and to tell you if you move the finger up or down.
• Vibration sense is transmitted along the same dorsal pathways as proprioception. It can be tested by placing a vibrating low frequency tuning fork on the patient's wrist and asking him to tell you when it stops vibrating. This distinguishes the vibration sense from just feeling pressure.
• Another way to test joint position sense is to ask the patient to hold out his arms, extended in front of him with his fingers spread. Ask him to close his eyes and hold the position. Without visual feedback, do the arms drift up or down? You may give a gentle push to an arm and see if it swiftly resumes its position.

The segmental level of sensation is:

• Posterior aspect of the shoulders is C4
• Lateral aspect of the upper arms is C5
• Tip of the thumb is C6
• Tip of the middle finger is C7
• Tip of the little finger is C8
• Medial aspect of the lower arms is T1

Some aspects of sensation may be deficient because of central lesions. Astereognosis is the inability to recognise common objects by touch. It may result from lesions in the posterior columns or the sensory cortex. It is tested by asking the patient to close his eyes, placing an object in his hand and asking him to recognise it. Typical objects may be a 50 pence piece or a key.

Another test of cortical function is called extinction. Touch the patient in one place and ask him to open his eyes and point to the spot where he was touched. Repeat but this time, touch the patient in two places on opposite sides of their body, simultaneously. Again, ask him to point to where he felt the touch. With extinction he will point to only one place. With lesions of the sensory cortex in the parietal lobe, the stimulus is not felt on the side opposite to the damaged cortex. The sensation is "extinguished".

As with most aspects of examination, this starts simply by looking at the patient.

Inspection

• Note the resting posture. Is there unusual rotation or clawing of the hand? Is the patient symmetrical?
• An upper motor neurone (UMN) lesion will produce disuse atrophy in the affected muscles. A lower motor neurone (LMN) lesion or myopathy will produce much more marked atrophy.
• A LMN lesion or myopathy will produce fasciculation. This is spontaneous discharges of groups of muscle cells to produce twitches in little areas of muscle. Striking an area with a jerk hammer may stimulate such action.

Tone

Tone is raised in an UMN lesion and reduced in a LMN lesion but the latter can be more difficult to distinguish from normal.

Ask the patient to relax and take his hand in your hand and support the elbow with the other hand. Flex the elbow so that the palm is in front of the shoulder and facing it. Gently, but fairly swiftly, passively extend the arm, at the same time supinating it. Return it to its position with flexion and pronation and repeat the movement a few times. Note the degree of resistance to movement.

• In an UMN lesion there is clasp knife rigidity. There is resistance to movement in the first part of extension and supination and then the resistance rapidly fades. It is like the resistance on opening a pen knife.
• In Parkinson's disease, there is constant hypertonia throughout the range of movement. This is lead pipe rigidity as it is like bending a lead pipe.
• In Parkinson's disease a tremor may be superimposed on lead pipe rigidity to give cog-wheel rigidity.

Another cause of apparent increased tone is myotonica. In this the muscles are slow to relax. The classical physical sign is to shake hands with the patient who is then apparently reluctant to let you have your hand back. Striking the thenar eminence with a jerk hammer make cause a sustained contraction that produces a dent in the muscle or abduction of the thumb that is sustained for a few seconds.

Simply noting that a muscle or a group contract is not enough. A robust assessment of power is required. This almost involves grappling with the patient and for a small doctor assessing a powerful man, it can be quite demanding. Power is usually graded from 0 to 5 with 0 being no contraction and 5 being full and normal power for the patient's physique. The scale is skewed towards the weak end and some people enhance it with supplements such as 3+/5 or 2–/5. The last digit indicates a scale of 0 to 5 as sometimes a scale of 0 to 4 is used.

• Ask the patient to stand and ask him to abduct his arms to about 45° with elbows flexed. Stand behind him and try to push his arms down to his side. This should be very difficult to achieve.
• Ask him to sit or lie on the couch or to sit in a chair. It is often easier to perform the rest of the examination with the patent sitting near the desk rather than on the couch.
• With the elbow at about 90°, ask him to pull against you.
• Then, from the same position, hold the elbow steady with one hand and resist extension with the other.
• Ask him to squeeze your wrist as tightly as possible. Be careful if he is very muscular and testing flexion of the wrist may be safer.
• Place your hand on the desk and ask him to lay his wrist across yours with the wrist flexed. With your other hand, resist attempted extension of the wrist.
• Ask him to spread his fingers and to resist your attempts to squeeze them together. Assess the fingers in pairs.
• Assess flexion, extension, abduction and adduction of the thumbs.

A potentially useful technique to assess power when it is not markedly reduced is called pronator drift. Ask the patient to extend and raise both arms in front of him with palms up, about the level of his shoulders. Ask him to maintain the position with his eyes closed and count up to 10. Normally the arms will remain in place. If there is weakness of the upper limb there will be a positive pronator drift, in which the affected arm will pronate and fall. This is one of the most sensitive tests for upper extremity weakness.

Pronator drift indicates UMN weakness. In this condition, supination is weaker than pronation in the upper extremity, leading to a pronation of the affected arm. This test is useful to confirm consistency. If a patient fakes weakness, he will almost always drop the arm without pronating it.

These are often referred to as deep tendon reflexes. Basically they represent a spinal reflex to a sudden, short stretching of the muscle. The requirements of a good jerk hammer and how to use it are discussed in neurological history and examination. UMN lesions will produce an enhanced reflex. LMN lesions will produce a diminished or absent response. Reflexes can be graded from 0 that is no respnse to 5 that is brisk and sustained clonus. Sensory input is also required. The briskness of the jerk is probably less important than any difference between the two sides.

Techniques will vary between individuals and the following description is a suggestion rather than a dictum.

• To elicit the biceps reflex, get the patient to relax with his elbow joint at about 120°. Support his arm with your own arm as you place your thumb over the biceps tendon. Let the hammer fall on your thumb so that your thumb transmits the movement to the tendon. There should be a brief but definite contraction of the biceps.
• To perform the triceps jerk, support the patients arm by holding the wrist with the elbow at about 90°. Support the weight of the arm and get him to relax. Strike the triceps tendon just above the olecranon.
• The third tendon reflex that is routinely tested in the arm is often called the supinator reflex although it is actually the brachioradialis that is tested. Support the patient's arm in a manner similar to the technique for the triceps reflex. The elbow should be at or around 90° again. Let the hammer fall to strike the tendon about 7 or 8cm above the wrist. The response is supination.

There are other reflexes that may be tested including finger jerks and Hofman's sign. They are UMN lesion signs. They are difficult to elicit but may be found in the further reading.

Reinforcement

If a reflex is negative it may be possible to enhance it by reinforcement. This involves getting the patient to contract muscles briefly whilst the test is performed. The muscles to be contracted isometrically are in the lower limb to reinforce jerks in the upper limb and vice versa. When testing the upper limb you may ask the patient to push out with his legs against a firm object such as a heavy desk. Call, "Push" and he pushes for about 2 or 3 seconds and about 1 second after he starts the push, strike with the hammer.

Power alone is inadequate without the ability to coordinate movement. Coordination is likely to be poor if power is weak. Incoordination may be disproportionate to reduction of power, if any. Coordination involves power, sensory feedback, especially proprioception and central control, especially by the cerebellum. There are a number of tests. Remember to test both sides of the body.

• Hold an extended index finger about 30 or 40cm away from the patient and ask him to use his index finger to touch yours and then his nose. Get him to do this several times, moving your finger a little each time.
• Ask him tap to the back of his hand as rapidly as possible.
• Dysdiadochokinesis is tested by asking the patient to hold up his hands with his palms facing forwards at about the level of his shoulders, and rapidly to pronate and supinate.

The segmental innervation of the reflexes is:

• Biceps C5,6
• Brachioradialis (supinator) C5,6
• Triceps C7

There are a number of neurological lesions that should be recognised without specialist knowledge. Many have their own articles to which the reader is referred and so they will be mentioned just briefly here.

• Erb's palsy is most often seen in neonates who have had trauma to the upper brachial plexus during delivery. A classical feature is the internal rotation of the arm with flexion at the wrist, said to be reminiscent of a porter turning away but soliciting a tip.
• Klumpe's palsy is damage to the lower brachial plexus. It may arise from falling asleep with the arm slumped over the back of a chair. This is usually a very deep sleep induced by alcohol intoxication. It can also occur from pressure in the axilla from the use of shoulder crutches. There is paraesthesia along the inner aspect of the arm and weakness of the intrinsic muscles of the hand. If it is necessary to change from shoulder crutches to elbow crutches, the weakness of the hands poses difficulty. This palsy usually recovers with time.
• Ulnar neuritis usually occurs as a result of injury near the elbow.
• Carpal tunnel syndrome is produced by compression of the median nerve in the wrist.
• Problems with use of the upper limbs may result from stroke, cerebellar ataxia or Parkinson's disease.
• Problems may arise in the neck as cervical spondylosis and cervical disc protrusions and lesions.
• Musculocutaneous nerve lesions may mislead as it is a peripheral nerve but it supplies motor fibres only above the elbow and sensory fibres only below the elbow.
• Syringomyelia is a rare but fascinating disease in which the central canal of the spinal cord expands and impinges on the neuronal pathways. For a full description the reader is referred to the article. The classical feature is dissociated sensory loss. Pain and temperature sensation are lost, while light touch, vibration and position senses are intact. As the cavity enlarges into the posterior columns, position and vibration senses in the feet are lost and astereognosis may result.