Posts Tagged ‘Reflexes’

Upper Limbs

Monday, August 25th, 2014

Subtitles in English for this video can be displayed by clicking on CC (first button on the bottom right hand corner of the video).

Inspection of the Upper Limbs

After adequate exposure, one should then lay the patient’s arms out comfortably.

The examiner should stand at the end of the bed / facing the patient if the patient is sitting, and inspect for any obvious asymmetry, wasting or abnormal posturing. If the patient is lying down, one should then stand on the right hand side of the patient and inspect the upper limbs in greater detail, focusing on whether there is any muscle wasting (proximal and / or distal muscles), fasciculations, scars and tremor. If the patient’s arms initially laid in the prone position, the examiner could then place them at the “palm-up position” and examine the ventral aspect of the upper limbs. The opposite could be done if the patient’s arms are initially laid in the “palm-up position”.

Eliciting Fasciculations of the Upper Limbs

If there are no fasciculations visible on inspection, one can tap onto the muscle bulk gently, which may bring out the fasciculations in a patient with an underlying lower motor neuron disorder. However, one common pitfall is that students often rush through tapping of the muscle bulk, but do not observe long enough for the fasciculations to appear. Often a time, the fasciculations may be visible without tapping if the muscle bulk was examined in detail (see videos of a patient with fasciculations under ‘lower motor neuron signs’).

Determining the Tone of the Upper Limbs

The tone of the upper limbs could be determined via examining the elbow and wrist joints as shown in the video. The patient’s tone should then be classified as normal, hypertonic or hypotonic. One may also be able to delineate whether the patient has lead-pipe rigidity, cogwheel rigidity (e.g. in parkinsonism), or spasticity (e.g. in patients with an upper motor neuron lesion).

Determining the Power of the Upper Limbs

The power of the upper limbs could be determined as shown in the video. One should examine the power of muscles involved in abduction and adduction of the shoulders as well as flexion and extension of the elbows, wrists and fingers. The power of the small hand muscles: finger abduction, thumb abduction and thumb opposition should then be elicited. Further detailed examination of other muscles could also be performed if the clinical history or physical examination raises clinical suspicion.

The power of the muscles should then be graded according to the Medical Research Council (MRC) scale for muscle strength as follow:

  • Grade 5: Muscle contracts normally against full resistance
  • Grade 4: Muscle strength is reduced but muscle contraction can still move joint against resistance
  • Grade 3: Muscle strength is further reduced such that the joint can be moved only against gravity
  • Grade 2: Muscle can move only if the resistance of gravity is removed
  • Grade 1: Only a trace or flicker of movement is seen or felt in the muscle, or fasciculations are observed in the muscle
  • Grade 0: No movement is observed

Eliciting the Upper Limb Reflexes

The reflexes of the upper limbs including the biceps, triceps and supinator reflex should be examined as shown in the video. The patient’s upper limbs should be fully relaxed. To elicit the biceps tendon reflex, roll the thumb along the biceps tendon and gently tap onto the thumb with the tendon hammer. The tendon hammer should be held towards the end and the wrist should be used to ensure a good swinging motion.

If the reflex is absent, one should proceed by performing the reinforcement maneuver (Jendrassik maneuver) by asking the patient to clench his or her teeth tightly upon tapping the tendon with the tendon hammer. The patient’s reflex should then be classified as normal, brisk (hyper-reflexic), hypo-reflexic or absent.

Testing Coordination of the Upper Limbs

A video of how rebound is elicited is also shown here.

The patient’s coordination should be assessed by the finger-nose test (to elicit intention tremor and dysmetria) and asking the patient to perform rapid alternating movements of the hand (to elicit dysdiadochokinesia).

Once again, clear, simple instructions are vital. Common pitfalls of medical students, is that during the finger-nose test, the examiner’s finger is either held too close to the patient (thus intention tremor could not be accurately assessed) or too far away. The examiner’s finger should be ideally at arm’s length from the patient. It is useful to hold onto the patient’s hand and perform the test with the patient first before asking the patient to perform it himself.

Lower Limbs

Monday, August 25th, 2014

Subtitles in English for this video can be displayed by clicking on CC (first button on the bottom right hand corner of the video).

Inspection of the Lower Limbs

After positioning the patient on the bed and ensuring adequate exposure, the lower limbs should be inspected as follow:

The examiner should stand at the end of the bed and inspect for any obvious leg length discrepancy, asymmetry, wasting or abnormal posturing. One should then stand on the right hand side of the patient and inspect the lower limbs in greater detail, focusing on whether there is any muscle wasting (proximal and / or distal muscles), fasciculations, scars, tremor, pes cavus and clawing of toes.

Eliciting Fasciculations of the Lower Limbs

If there are no fasciculations visible on inspection, one can tap onto the muscle bulk gently, which may help bring out the fasciculations if an underlying lower motor neuron lesion is present. However, one common pitfall of medical students is that they often rush through the tapping of the muscle bulk, but do not observe long enough for the fasciculations to appear.

Determining the Tone of the Lower Limbs

The tone of the lower limbs could be determined first of all by gently rolling the lower limb on the bed as if it was a log. In patients with hypertonia, there would be increased resistance with this manoeuvre. The normal swinging motion of the foot will also be reduced. This should be followed by gently lifting up the thigh of the lower limb and releasing it back onto the bed. In patients with hypertonia, the heel of the foot would often elevate from the surface of the bed. The tone of the lower limb is classified as normal, hypertonic or hypotonic.

Determining the Power of the Lower Limbs

The power of the lower limbs could be determined as shown in the video. One should examine the flexion, extension, adduction and abduction of the hip muscles, followed by extension and flexion of the knee muscles. Finally, foot dorsiflexion, dorsiflexion of the big toe, foot plantar flexion, foot inversion and eversion should be examined.

Again, the power of the muscles should then be graded according to the Medical Research Council (MRC) scale for muscle strength as follow:

  • Grade 5: Muscle contracts normally against full resistance
  • Grade 4: Muscle strength is reduced but muscle contraction can still move joint against resistance
  • Grade 3: Muscle strength is further reduced such that the joint can be moved only against gravity
  • Grade 2: Muscle can move only if the resistance of gravity is removed
  • Grade 1: Only a trace or flicker of movement is seen or felt in the muscle, or fasciculations observed in the muscle
  • Grade 0: No movement is observed

One should then compare the muscle power between the right leg and left leg, as well as between proximal and distal leg muscles.

Eliciting the Lower Limb Reflexes

The reflexes of the lower limbs including the knee jerk, Achilles tendon reflexes and plantar reflexes can be examined as shown in the video.

Testing Coordination of the Lower Limbs

The heel-shin test is performed as demonstrated in the video shown here.

Examining the Gait

Examining the Cranial Nerves

Monday, August 25th, 2014

Subtitles in English for this video can be displayed by clicking on CC (first button on the bottom right hand corner of the video).

General Inspection

During the general inspection of the cranial nerves, we should look for whether the patient has any ptosisabnormal eye movements and facial asymmetry. We should also inspect for whether there are any neuro-cutaneous features (for example in patients with tuberous sclerosis and neuro-fibromatosis), syndromal features etc.

Cranial Nerve I (Olfactory Nerve)

Cranial Nerve II (Optic Nerve)

Visual Acuity

Visual Fields

Inspection of the Pupils

Direct and Consensual Light Reflexes

The Swinging Torch Test

Accommodation Reflex

Cranial Nerves III (Oculomotor Nerve), IV (Trochlear Nerve) and VI (Abducens Nerve)

Cranial Nerve V (Trigeminal Nerve)

Cranial Nerve VII (Facial Nerve)

Cranial Nerve VIII (Vestibulocochlear Nerve)

Cranial Nerves IX (Glossopharyngeal Nerve) and X (Vagus Nerve)

Cranial Nerve XI (Accessory Nerve)

Cranial Nerve XII (Hypoglossal Nerve)

Up-going Plantar Reflex

Wednesday, August 20th, 2014

To elicit this sign, the examiner strikes the patient’s sole using a blunt orange stick, starting from the heel, along the lateral border of the sole then medially to the base of the first toe. As one can see from the two videos, the patient demonstrates dorsiflexion of the big toe when testing for the sign. In some patients, there may also be fanning of the toes which is not very obvious in these two cases. Sometimes, the sign can also be elicited by striking other areas of the lower limb, such as the tibia and the ankle. The patient in the first video had a severe right cortical infarct resulting in left-sided upper motor neuron signs, whilst the patient in the second video had a history of transverse myelitis due to neuromyelitis optica resulting in upper motor neuron signs of both lower limbs.

Discussion of the sign

Up-going plantar reflex, or a positive Babinski’s sign, is considered a ‘hard’ neurological sign, which are signs that are objective and difficult to mimic. It is an upper motor neuron sign and any lesion along the cortico-spinal tract from the motor cortex to the spinal cord may result in this phenomenon. It has been proposed that loss of upper motor neuron control to local spinal circuits reproduces this primitive plantar reflex. It may be physiological in children before 1 year of age, but is otherwise pathological in older individuals, where the normal plantar response is downgoing. Of note, is that the foot should be fixed when eliciting the sign to minimise a withdrawal response, and the first direction of toe movement should be noted.

Also, as eliciting the sign often causes discomfort to the patient, it is preferable to use the blunt end of an orange stick when examining for the sign. Use of sharp objects (e.g. keys, pens or the sharp end of a tendon hammer) is discouraged. It is also of courtesy to warn the patient, whenever possible, that there will be some discomfort whilst testing for the sign.

Areflexia

Wednesday, August 20th, 2014

The knee-jerk, ankle-jerk and plantar reflexes are being examined in this patient. There is a slight down-going plantar reflex on the right side. Otherwise, all other reflexes are absent.

Discussion of the sign

Areflexia may indicate deficits in the reflex loop. This may be due to a lesion involving the sensory neuron or the lower motor neuron in which the location of the pathology may be at the peripheral nerve, spinal roots or the spinal cord.

Neuropathy is an important cause of this sign. There may be an isolated peripheral nerve lesion, as in peripheral nerve injuries or radiculopathies; or patients may have multiple nerves involved such as mononeuritis multiplex or peripheral neuropathy. This patient presented with an ascending weakness involving the four limbs and was noted to be areflexic. She was subsequently diagnosed to have Guillain Barré syndrome.