Neurological examination quiz Part 1

The minimum difference in diameter between the dominant and non dominant leg considered abnormal is 1cm. (link)

The minimum difference in diameter between the dominant and non dominant arm considered abnormal is 0.5cm. (link)

Random generalised twitches are pathological and their presence implies a lower motor neurone lesion. They are of the same rapidity and strength as benign fasciculations, however benign fasciculations are characterised by a repetitive twitch in the same muscle fibre, whereas pathological fasciculations tend to be random and generalised in a muscle. (link)

Fasciculations may be difficult to see in overweight patients and are easiest to see in the first dorsal interosseous muscle of the hand. Strong muscle contraction or percussion may increase the frequency of the fasciculations following relaxation. Fasciculations are rare following peripheral nerve lesions and can be caused by motor neurone disease, motor root compression, motor neuropathies and myopathies. (link)

When tone is normal, rapid passive flexion of the knee usually raises the heel off the bed slightly and transiently. If the heel drags across the bed from the start, this indicates hypotonia. If the heel is jerked upward, this indicates increased tone. Reinforcement techniques are used to increase the strength of weak reflexes, but do not usually increase muscle tone. (link)

Clasp knife rigidity is due to a heightened stretch reflex from an upper motor neuron lesion. Rapid passive flexion and extension of the elbow or knee produces a transient increase in resistance that occurs after a period of normal resistance, and is then overcome. (link)

With lead pipe rigidity the increase in tone is equal in the flexors and extensors and is felt throughout the range of movement. It may be easier to detect with slow movements and may gradually increase in intensity with repeated motion. (link)

Cog wheel rigidity is a rapid, regular series of resistances during passive movement. It may occur in essential or familial tremor in the presence of normal tone and is one of the classical  features of Parkinsonism. (link)

Gegenhalten phenomenon is the resistance by the patient against any passive movement. When present attempted movement is met with an equal and opposing force. It is usually associated with diffuse cerebral disease and advanced dementia. It is derived from the german ‘gegen’ – against, and ‘halten’ – to stop.

Hoover’s sign is as follows: with the patient lying in bed, place the palm of the hand between the bed and the heel of the weak limb and ask the patient to raise their unaffected leg. The presence of downward force in the weak leg and the lack of downward force under the good leg when instructed to raise the weak leg indicates feigned weakness. There is no contromano phenomenon! (link)

Clonus is a repetitive contraction of a muscle or muscle group demonstrated by suddenly stretching a muscle. One to two beats of clonus at the ankle is normal in those with naturally brisk reflexes but is considered pathological if it is present at any site other than the ankle or if more than 2 beats are present at the ankle, except in neonates when it can be normal, if not sustained. Fast beats with slow relaxation on lateral gaze is typical of horizontal nystagmus, not clonus. Clonus does not alter the normal pattern of a rapid contraction and longer relaxation of a deep tendon reflex, although tendon reflexes are usually brisk. (link)

Muscle power is assessed across joints. The joint is isolated by stabilising the part proximal to the joint with one hand whilst applying force to the limb proximal to the next joint with the other hand. The same segment is then assessed in the opposite limb for comparison. The grading of muscle power is: 0 = complete paralysis; 1 = flicker of contraction; 2 = movement with gravity excluded; 3 = movement against gravity but not resistance; 4 = movement against resistance; 5 = normal power. (link)

When testing reflexes, support the limb to ensure the muscle is relaxed and the muscle should be at its resting length or slightly stretched (e.g. slight knee flexion for the patellar reflex). (link)

Reflexes are usually graded using the following scale: 0 – absent with reinforcement; 1 – present but decreased in amplitude and velocity from the normal range and elicited with reinforcement; 2 – normal amplitude and velocity without reinforcement; 3 – increased in amplitude and/or velocity with spread to adjacent site; 4 – increased in amplitude and/or velocity with spread to adjacent site and duplication of the jerk or clonus. (link)

A plantar reflex would normally be present after 1 year of age. (link)

The nerve roots involved in the biceps reflex are C5-6. (link)