Tag Archives: Cushing’s sign

Difference between Cushing’s Sign and Cushing’s Reflex

Cushing’s Sign also goes by the name Cushing’s Triad.
It is a late sign of increased intracranial pressure and is defined by three signs:
1. Hypertension
2. Bradycardia
3. Irregular breathing

It occurs whenever something occupies the already limited space in the skull. The space can be occupied by:
1. Blood – As seen in cerebrovascular accidents that result in bleeding (cerebral hemorrhage due to ruptured aneurysm or trauma)
2. Enlarging lesion – Brain tumor
The pressure on the brain tissue causes it to shift across the structures within the skull (this is called brain herniation). This can be rapidly fatal.

Cushing’s sign should be suspected in any person who has had a recent head injury, a recent brain surgery or shows sudden altered level of consciousness.

Cushing’s Reflex goes by a lot of names – Cushing’s Effect, Cushing’s Reaction, Cushing’s Phenomenon even Cushing’s Law!
As is the case with any other reflex, Cushing’s reflex is a physiologic response. It is a physiologic response to increased intracranial pressure via the sympathetic and parasympathetic nervous system.
It has four stages that can be briefly described as follows:

The body tries to increase blood supply to the brain – Stage 1 is due to sympathetic system activation leading to tachycardia and hypertension.
Baroreceptors respond to the sympathetic system activation – Stage 2 is due to parasympathetic system activation leading to bradycardia.
Stage 3 and 4 involves irregularity in breathing caused by functional abnormality of the brainstem due to the increased intracranial pressure, tachycardia and bradycardia.

The bottom line – Cushing’s Sign occurs as a result of Cushing’s Reflex.

1 Comment

Posted by on January 7, 2012 in Medical


Tags: , , , ,