Persistent vegetative state

Last updated: March 16, 2022

Summarytoggle arrow icon

Persistent vegetative state (PVS) is a clinical condition in which function of the cortex is impaired while function of the brainstem is preserved for a period of more than one month. Traumatic brain injury and diffuse cerebral hypoxia are the most common etiologies. Patients in PVS may appear awake but are not aware or conscious, and they are unable to communicate with others or purposefully interact with their environment. However, they are still able to breathe on their own, sleep-wake cycles are preserved, and autonomic function is at least partially retained. PVS is a clinical diagnosis, and it is important to differentiate it from coma (no sleep-wake cycles) and brain death (no sleep-wake cycles or brainstem function). No definitive treatment exists. Although most patients remain in a vegetative state for years, a few may recover spontaneously. A vegetative state is declared permanent when recovery is very unlikely (i.e., PVS due to trauma lasting more than 1 year or PVS due to a nontraumatic cause lasting more than 3 months).

Etiologytoggle arrow icon


Pathophysiologytoggle arrow icon

Widespread damage to the white matter of both cerebral hemispheres and/or the thalamus bilaterally, without damage to the brainstem. This results in reduction of cortical function with preserved brainstem control of respiration, cardiac function, sleep-wake cycles, and reflexes.


Clinical featurestoggle arrow icon

  • Usually preceded by comatose state requiring intensive care and gradual recovery of autonomic function
  • But lack of recovery of higher mental function after 1 month and the following features:
    • Intact sleep-wake cycles with periods of wakefulness
    • Loss of perceptual and self-awareness
      • Lack of purposeful response to external stimuli (e.g., tactile, auditory, visual, etc.)
      • Inability to communicate and lack of apparent language comprehension
      • Disconjugate eye movements with loss of fixation
      • Occasional nonpurposeful limb movements and spontaneous smiling, crying, grunting, or screaming
    • Autonomic function and reflexes retained to variable degrees


Diagnosticstoggle arrow icon

  • Clinical diagnosis based on ≥ 1 month of intact sleep-wake cycles, loss of perception and self-awareness, and autonomic functions retained to variable degrees
  • Neuroimaging
    • CT/MRI: nonspecific diffuse or multifocal abnormalities involving the gray and white matter; decrease in cerebral blood flow
    • PET: diffuse reduction of the glucose metabolic rate of the brain
  • EEG: diffuse generalized polymorphic delta and/or theta activity

Differential diagnosestoggle arrow icon

Disorders of consciousness
Persistent vegetative state Coma Locked-in syndrome Brain death
Perceptual and self-awareness Absent Absent Present Absent
Sleep-wake cycles Present Absent Present Absent
Motor function No purposeful movement No purposeful movement Quadriplegia and bulbar or pseudobulbar palsy; eye movement preserved None or only reflex spinal movements
Brainstem reflexes Variable Variable Variable Absent
Respiratory function Normal Depressed, variable Variable Absent


The differential diagnoses listed here are not exhaustive.

Prognosistoggle arrow icon

  • The vegetative state is defined as permanent if recovery is very unlikely.
  • Likelihood of recovery depends on etiology
    • PVS due to trauma → recovery unlikely after ≥ 12 months
    • PVS due to nontraumatic etiology → recovery unlikely after ≥ 3 months
  • Low life expectancy
  • Withdrawal of life support may be considered if the chances of recovery are very low (e.g., ≥ 12 months in traumatic PVS). However, in patients without advanced directives, it is a complicated legal and ethical question that requires discussion with family members and experts.


Treatmenttoggle arrow icon

  • Treatment is supportive; no definitive treatment exists.

Referencestoggle arrow icon

  1. Caplan LR. Locked-in Syndrome. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. Last updated: August 25, 2014. Accessed: April 3, 2017.
  2. Ashwal S, Cranford R, Bernat JL, et al. Medical aspects of the persistent vegetative state. N Engl J Med. 1994; 330 (21): p.1499-1508.doi: 10.1056/nejm199405263302107 . | Open in Read by QxMD
  3. Zeman A. Persistent vegetative state. The Lancet. 1998; 351 (9096): p.144.doi: 10.1016/s0140-6736(05)78109-5 . | Open in Read by QxMD
  4. Vegetative State and Minimally Conscious State. Updated: December 1, 2017. Accessed: November 28, 2018.
  5. Adams JH. The neuropathology of the vegetative state after an acute brain insult. Brain. 2000; 123 (7): p.1327-1338.doi: 10.1093/brain/123.7.1327 . | Open in Read by QxMD
  6. Pathophysiology of the Vegetative State. Updated: March 30, 2010. Accessed: November 28, 2018.
  7. Wijdicks EFM, Cranford RE. Clinical diagnosis of prolonged states of impaired consciousness in adults. Mayo Clin Proc. 2005; 80 (8): p.1037-1046.doi: 10.4065/80.8.1037 . | Open in Read by QxMD

Icon of a lock3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer