Method of elicitation
Keep a finger on the upper lip and a direct tap on the lips with the examiner's finger lightly over it.
Puckering and protrusion of the lips is seen.
pressure of the knuckle against the center of upper lip provokes con-traction of the orbicularis oris muscle
This is also seen in B/l UMN facial palsy and diffuse cerebral damage.
Ask the subject to open his mouth widely and then touch the mucous membrane covering the palate using a spatula. This produces reflex contraction of the palatal muscles which results in sudden elevation of the palate.
Receptors : Touch receptors of the palatal mucosa
Afferent limb : Glossopharyngeal nerve and Trigeminal nerve
The corneal reflex, also known as the blink reflex, is an involuntary blinking of the eyelids elicited by stimulation of the cornea. The purpose of this reflex is to protect the eyes from foreign bodies and bright lights (the latter known as the optical reflex)
The edge of cornea (limbus) is touched with a wisp of cotton, with the patient looking upward in the opposite direction
The nasociliary branch of the ophthalmic branch (V1) of the 5th cranial nerve (trigeminal nerve) sensing the stimulus on the cornea(afferent fiber).
The temporal and zygomatic branches of the 7th cranial nerve (Facial nerve) initiating the motor response (efferent fiber).
The centre (nucleus) in the pons of brain stem.
Use of contact lenses may diminish or abolish the testing of this reflex.
Response is brisk closure of both the eyes
Stimulation should elicit both a direct and indirect or consensual response (opposite eye). The reflex consumes a rapid rate of 0.1 second. The evolutionary purpose of this reflex is to protect the eyes from foreign bodies
Interpretation:
An absent corneal reflex may be due to
Sensory loss in Vi (e.g. neuropathy or ganglionpathy)
Weakness or paralysis of the facial muscles (myopathy)
Facial nerve (facial palsy, for example Bell's palsy)
Brain stem disease.
For a myopathy to cause a loss of the blink reflex the weakness has to be very severe, example chronic progressive external ophthalmoplegia (CPEO)
Hyporeflexia is a condition characterized by the absence or diminished reflex in reaction to an applied stimulus. This condition is associated with the lower motor neuron disease defined by a deficit in the nerve that runs through the spinal cord going to the extremities.
Hyporeflexia is the hallmark of LMN lesion .It is also seen in UMN shock LMN lesions
AHC
Root
plexus
nerve
muscle
Neurological shock
Severe extrapyramidal rigidity
Contracture
Peripheral neuropathy
GBS
SACD
Tabes dorsalis
Friedreich's ataxia
Periodic paralysis
Cerebral or spinal shock
Isolated loss of a rellex usually suggests radiculopathy.
Symmetrical loss of rellex may be found in peripheral neuropathy.
Reflexes may be absent if the patient is unable to relax.
A reflex seems lost or diminished in defect of technique, relaxation, or observation.
In a screening examination you it more convenient to integrate the reflex examination into the rest of the examination of that part of the body; that is, do the lower extremity reflexes when examining the rest of the lower extremity. When there is an abnormality of the reflexes is noted , however, the reflexes should be examined as a group with careful attention given to the technique of the examination.
Reliable test results are best obtained when the patient is fully relaxed
Explain the procedure to the patient
If you fails to get any response with a specific reflex that can usually occcur with ankle jerks then try the following:
Several different positions of the limb.
Get the patient to put slight tension on the muscle being tested. One method of achieving this is to have the patient strongly contract a muscle not being tested.
In the upper extremity, have the patient make a fist with one hand while the opposite extremity is being tested.
If the reflex being tested is the knee jerk or ankle jerk, have the patient perform the "Jendrassik maneuver," a reinforcement of the reflex . The patient's fingers of each hand are hooked together so each arm can forcefully pull against the other. The split second before you are ready to tap the tendon, say "pull."
In general, any way to distract the patient from what you are doing will enhance the chances of obtaining the reflex. you can instruct the patient to count or give the names of children are examples.
The best position to elicit reflex is that the patient to be sitting on the side of the bed or examining table. The Babinski reflex hammer may be used..
Use a brisk but not painful tap.
Use your wrist, not your arm, for the action.
In an extremity a useful maneuver is to elicit the reflex from several different positions, rapidly shifting the limb and performing the test. Use varying force and note any variance in response.
After obtaining the reflex on one side, always go immediately to the opposite side for the same reflex so that you can compare them.
You should note the following features of the reflex response:
Amount of hammer force necessary to obtain contraction
Velocity of contraction
Strength of contraction
Duration of contraction
Duration of relaxation phase
Response of other muscles that were not tested. When a reflex is hyperactive, that muscle often will respond to theexamination of a nearby muscle. A good example is reflex activity of a hyperactive biceps or finger reflex when the brachioradialis tendon is tapped. It is termed "overflowing" of a reflex.
In hyperactive stretch reflex there is increased speed of response, duration and amplitude of movement.
Hyperreflexia can be either exaggerated or brisk response.it is very difficult to differentiate between the two. The term exaggerrated reflex means tbe amplitude and duration of the limb movement is more and brisk rellex means an increase in amplitude but not increase in duration,Brisk reflex may be a normal variant its presence may confuse us as abnormal but is only of pathological significance when it is asymmetrical (comparing with the other side) or if associated with other signs of UMN lesion (spasticity. Babinski’s sign etc.)
Brisk = Increase in amplitude of muscle contraction Exaggerated = Increase in amplitude and duration of musle contration
Hyperactivity of muscle indicate an interruption of corticospinal and other descending pathways that influence the reflex arc due to a suprasegmental lesion, that is, a lesion above the level of the spinal reflex pathways.
Hyperactivity of muscle reflex is seen in the following conditions
As a sign of UMN lesion - pyramidal lesion and associated damage of reticulospinal and vestibulo spinal tract.
Psychoneurosis - anxiety -amplitude of movement is increased.Reflexes may be brisk if the patient is agitated, frightened, or anxious.
Tetany
Tetanus
Early phase of neuritis - increased irritability of peripheral nerve
Paralysis of antagonist - increased knee jerk in paralysis of antagonist hamstring muscle
Spasticity often occurs with clonus. It involves long-term muscular tightness.
Spasticity, as seen in clonus, is produced by damaged nerves among the brain, spinal cord, and muscles. This abnormal activity is disrupt muscle movement by causing involuntary contractions, stiffness, and pain.
Neurological and muscular issues that can occur alongside clonus can include:
Overactive deep tendon reflexes
Fixed joints, known as contractures
Hypertonicity
Scissoring-Involuntary leg-crossing, sometimes called scissoring
Clonus, is usually encountered in the knee or ankle, it is a classic symptom of spasticity occurring as a result of lesions in upper motor neurons.
Wrist clonus significance is that it is much less common and can be confusing and misdiagnosed. Wrist clonus in patients affected with hemiplegia was described in lectures published in 1883 by the French neurologist Jean-Martin Charcot, who called this phenomenon as “provoked trepidation” and noticed that .These patients, on raising the paralysed arm, often experience a trembling similar to that which occurs in the lower limb under like circumstances. But the wrist-phenomenon, provoked or spontaneous, is much more uncommon.” Method of elicitation of wrist clonus
Hyperextend the wrist, sustained pressure is applied.
There is sustained clonic movement of the hand induced by sudden extension of the wrist.
Clonus is a series of involuntary, rhythmic, muscular contractions and relaxations. Clonus is a sign of upper motor neuron lesions involving descending motor pathways,
Ankle clonus is an involuntary tendon reflex that causes repeated flexion and extension of the foot. . More than four beats of clonus is pathological.It is the grade 4 ankle hyper reflexia.
There is repetitive ankle dorsiflexion and plantarflexion on passive dorsiflexion of the foot by the examiner till the force applied by the examiner is withdrawn. Method of elicitation of ankle clonus
Patient lies supine.
Support the flexed knee with your left palm (placed in the popliteal fossa) (with both the knee and ankle resting in 90° flexion)
Now briskly dorsiflex and partially evert the foot with your right hand sustaining the pressure (do not leave the hand after dorsiflexing). (heel should not touch the bed).
A series of contraction and relaxation of calf muscles are seen if a steady pressure is maintained on the foot by the right hand. Clonus is felt as repeated beats of dorsiflexion/plantar flexion.
Pathogenesis of ankle clonus
Ankle clonus is seen in people with damage to the neuronal pathways in the spinal cord or brain (an upper motor neurone lesion), elicited by a deliberate rapid, stretching of the ACHILLES TENDON, by forcibly flexing the foot. There is a rhythmic contraction of the calf muscles following a sudden passive dorsiflexion of the foot, the leg being semiflexed.The spinal reflex arc is intact but the normal control on it, from above, is abnormal. Causes of ankle clonus
Any spinal cord lesions, be it traumatic, neoplastic, pyogenic, vascular above the level of S1 can cause clonus.
This is because of the spasticity caused by the UMN type of injury causing hyper reflexia and clonus. Some other causes of clonus are
Plantar response is a local reflex arc modified by the pyramidal tract. Position of the patient
All the leg muscles should be visible and in a relaxed state. It can be achieved by positioning the patient in a way that the knee is slightly flexed and the thigh is externally rotated. The patient should be warned that the sole is going to be scratched and ask him to try to let his limb remain as floppy as possible. You should not be touched the toes. Stimulation
Many factors can influence the clinical response including the site of stimulation, the intensity of stimulation, and even the object used for stimulation . Any part of the leg can be stimulated, but the best technique is to stimulate the lateral plantar surface and the transverse arch in a single movement upto the middle metatarsophalangeal joint with a firm applicator lasting 5 to 6 seconds. Method of elicitation of elicitation of plantar reflex.
The patient lies supine with extended legs and there should be relaxation of the muscles of the Iower limb.
Hold the leg firmly above the ankle joint with examiners left hand
The outer border of the sole is scratched gently by a key (preferable). stick of the hammer or blunt needle.
Starting from the heel, go along the lateral border towards the little toe and then turn medially across the metatarsus upto the head ol 2nd metatarsus in a semicircular fashion.
You should never touch the ball of the great toe and the flexor creases of the toes.
The stimulus should not produce injury but it should be of noxious character as this is a ‘nociceptive reflex'.
You should stop stimulating the sole as soon as you get the first movement of the great toe.
Now do the test on the other side.
What are the precautions taken before eliciting plantar response ?
You should assess the following before checking the reflex
Assess the thickness of the sole—Thick sole may be responsible for absent response .
Look for any deformity of great toe—Move the great toe. and confirm that it is moving freely and
It is not rigid.
Knee must be extended.
Sole should be made warm (eg. by rubbing with your palm, specially in winter seasons
Leg should lie straight don't allow rotation of thigh.
One may assess the power of extensor hullucis longus before doing the test (optional).
What is the root value of this reflex ?
S2 Why the lateral aspect of the sole is stimulated ?
1.Lateral aspect of the sole is preferred because the receptors for extensor plantar response are present there in abundance and hence,even. In minimal UMN lesion, extensor plantar response is obtained by stimulating the lateral aspect of the sole.
2. If the medial aspect of the sole is stimulated, it may elicit flexion (even in the presence of UMN
lesion) of all the toes as part of the grasp relex,which is a different phenomenon.
Extensor plantar response is usually associated with brisk ankle reflex .But in certain conditions the plantar response is extensor with absent ankle jerk
Subacute combined degeneration.
Taboparesis (CPI plus tabes dorsalis).
Friedreich's ataxia.
Cauda-equina lesion (cauda equina lesion with lesion in conns medullaris)
Combined cervical and lumbar spondylosis
Plantar response is flexor with brisk ankle jerk
Sometimes it is observed in anxiety and thyrotoxicosis (exaggerated deep reflex).
Tricep jerk is an example of deep tendon reflex. Method of elicitation of tricep jerk?
Place the patients hand over his chest with the elbow flexed.
Support the hand at the wrist by your left hand so that the upper limb does not fall on the bed. Suddenly tap above the olecranon process ie on the tricenp tendon 5 cm above the elbow (never tap on the muscle)
Observe the following response
Contraction of triceps
Slight extension of the elbow.
Innervation of Triceps Jerk
Innervation of tricep jerk C7-C8 Nerve -Radial nerve What is Paradoxic triceps reflex:
This consists of flexion instead of extension of the forearm following stimulation of the triceps tendon.
This response appears when the arc of the triceps reflex is damaged
Occur in lesions of seventh and eighth cervical segments in such cases the stimulus calls forth a flexor response unopposed by the triceps muscle.
Paradoxical Triceps jerk is characterised by the following
Rhythmic reflex monophasic contractions and relaxations of hypertonic muscles in response to an abruptly applied and sustained strecth stimulus
Clonus is a rhythmical series of contractions in response to the maintenance of tension in a muscle, associated with increased gamma efferent discharge. It is elicitable when tendon reflexes are brisk after a corticospinal lesion
The word Clonus comes from the Greek word meaning "violent, confused motion. Significance of clonus is that it is a sign of neurological conditions, epecially associated with upper motor neuron lesions involving descending motor pathways
Clonus is a condition that produce involuntary muscle spasms and most commonly it affects the muscles at the end of a limb. Clonus mainly affects the knees, ankles, upper and lower arm muscles, and the jaw. The basic abnormality in clonus is
1. alternate involuntary muscular contraction and relaxation in rapid succession.
2. a continuous rhythmic reflex tremor that is initiated by the spinal cord below an area of spinal cord injury, when set in motion by reflex testing. Mechanism of clonus
The exact mechanism of clonus remains unclear. Two different hypotheses have been asserted regarding the development of clonus.
The most widely accepted explanation is that hyperactive stretch reflexes in clonus are caused by self-excitation.
Another alternative explanation for clonus is central generator activity that arises as a consequence of appropriate peripheral events and produces rhythmic stimulation of the lower motor neurons.
What are the association of clonus?
Clonus is always associated with
Brisk tendon reflex.
Spasticity and
Bablnski's sign-It is a very reliable sign of pyramidal tract lesion.
There arc two types of clonus :
Sustained clonus (true clonus).
Unsustained clonus (pseudoclonus).
Unsustained clonus (≤5 beats): may be physiological
Sustained clonus (>5 beats): regarded as abnormal
Sites for clonus examination in clinical neurology :
Ankle clonus.
Patellar clonus.
Jaw clonus (elicit the Jaw jerk to see a scries of closure and opening of the mouth).
Wrist clonus (elicited by sudden passive extension of the fingers).
3 and 4 are not routinely practised in clinical neurology.
Medical conditions that can cause clonus include:
Multiple sclerosis
Huntington disease
Spinal cord or brain injuries
Stroke
Meningitis
Cerebral palsy
Difference between a organic and non organic clonus
