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Superficial Abdominal reflexes -A complete guide

An abdominal reflex is a superficial neurological reflex that is elicited by  by stroking the abdomen around the umbilicus. It is a reflex with localising value in neurology.As it is a superficial reflex, it is polysynaptic.
Prerequisites for elicitation of abdominal reflex
  • Palpate the abdomen lor the degree of relaxation 
  • Explain the procedure to the patient
  • Apply  light non painful stimulus along the line of contraction of the muscle  
  • Stimulus should not be unpleasant
Method  of elicitation
The patient should lie flat, palpate the abdomen gently to assess the degree of relaxation and sensitivity of the skin. Then explain the procedure and illustrate on the chest.Lightly stroke the abdomen with a blunt object either a key or two point discriminator from without inwards, stimulating each of the four quadrants of the abdomen.
Normal response:There is homolateral contraction of the abdominal muscles and retraction of the linea alba and the umbilicus towards the area stimulated.

Root value of abdominal reflex
Superficial abdominal reflex center- T7 to T 12 spinal segments
Afferent is  posterior  root and efferent  is anterior  root of spinal nerves T7 to T12
  • Upper abdominal -T6-T8
  • Mid abdominal—T8-T10
  • Lower abdominal - T10-T12
What  are the types of Abdominal Reflex
1.Normal abdominal reflex
2.Absent abdominals
3.Fatiguable abdominals
4.Exaggerated abdominals
Exaggerated abdominal reflexes may be seen in psycho neurosis, or in anxiety states
5.Dissociated abdominals
In UMN lesion the superficial abdominal reflex is absent while the deep abdominal reflex is exaggerated.

6.Inverted abdominals
It is seen in unilateral abdominal paralysis
Stimulation of the paralysed side leads to contraction of the normal side & deviation of umbilicus to that side while the reflex is absent on the paralysed side
When Beevor's sign is positive, there is upper abdominal muscle contraction and retained upper abdominal reflexes.but there is absence of lower abdominal muscle contraction and reflexes (T10 - segment lesion).
  • Heavy stimulation will elicit a deep abdominal reflex which is often exaggerated in a corticospinal tract lesion
  • Lax or tense abdomen may result in absent abdominals
  • Abdominals are not always absent in multiple sclerosis
  • Difficulty in relaxing the abdominals may be circumvented by eliciting the jerk while the patient is upright
  • If the abdomen is lax, slight contraction can still be elicited by stimulation near the ribs and-inguinal ligament
  • Abdominal reflexes are retained till late in a motor neurondisease, cerebral diplegia, infantile hemiplegia inspite ot pyramidal system involvement.
  • There is unilateral loss of abdominal reflexes on the side of hemiplegia.