Many have vaguely heard of these two scary brain conditions – both sequelae to extensive brain damage. What does it mean when a loved one is diagnosed with locked-in syndrome, or in a persistent vegetative state? And how do they differ from one another?
These two conditions are somewhat opposites. Many confuse them. In Persistent Vegetative State (PVS), the person may open his eyes, but is not aware of his environment. In Locked-in Syndrome (LIS), the person is fully aware of his environment, but cannot talk or move.
To fully understand them, you’ll need to remember two brain structures:
(1) The cerebral cortex (upper brain): responsible for consciousness, awareness, cognition, reasoning, speech
(2) The brain stem (lower brain): the part of the brain that keeps you alive! It maintains breathing, houses the cranial nerves and contains nerve pathways that connect your upper brain to the spinal cord.
For a thorough review of human brain anatomy, read this article:
Parts of the Brain – Simplified
Persistent Vegetative State
“Awake but not Aware”
Causes: Damage to the upper brain (cerebral cortex). The upper brain is responsible for consciousness, awareness, cognition, reasoning, speech — thinking abilities in general. The lower brain (brain stem) is intact.
People in persistent vegetative states CAN:
- breathe on their own
- open and move their eyes (some can even track objects with their eyes)
- have regular sleep-wake cycles
- cry, laugh, smile, moan, scream spontaneously (not related to external stimulus)
- move their limbs slightly (only as a reflex)
People in persistent vegetative state CANNOT:
- understand his environment
- perform any voluntary action such as follow commands
- move his body beyond reflexive actions, such us raise his arms
“Conscious but Cannot Move”
Locked-in syndrome is a condition in which a person is completely conscious and aware of his environment, but cannot move due to complete paralysis of all voluntary muscles in the body except for the eyes. In fact, there’s a version called total locked-in
syndrome where the eyes are paralyzed as well. It’s considered the closest experience someone can have to being “buried alive.”
Cause: Damage to the anterior portion of the pons, which is part of the brain stem. The ventral or anterior portion of the pons contains majority of the motor nerve tracts that control voluntary movement. Since the brain stem also controls breathing and circulation, some locked-in patients have trouble breathing on their own.
The upper brain (cerebral cortex) is intact.
People with Locked-in Syndrome CAN:
- understand his environment
- perceive and process thought like any other person
- feel pain and other regular sensations
- have normal sleep-wake patterns
- (mostly) move their eyes, track objects and blink
People with Locked-in Syndrome CANNOT:
- move his body
- (occasionally) cannot even move his eyes
A brilliant French movie about Locked-In Syndrome was made in 2007 called The Diving Bell and the Butterfly. It tells the real life story of Jean-Dominique Bauby – from his stroke, his locked-in diagnosis, and how he was able to write an entire book by just blinking one eye. Highly, HIGHLY recommended!
Hopefully this entry helps family and friends understand and differentiate Persistent Vegetative State and Locked-in Syndrome. Both conditions are devastating to family, and in the case of LIS, exponentially more devastating to the patient! And remember:
- PVS and LIS are NOT coma. In coma, the person does not wake up at all
- PVS and LIS patients are NOT brain dead. In brain death, there is absence of total brain function, not just part of it. To learn more about brain death, read this entry: How to Determine Brain Death