Compare and contrast persistent vegetative state, locked-in state & akinetic mutism

Persistent vegetative state
* Loss of cognitive neurological function but retains non cognitive functions- respiration,BP, cardiac function etc.
* Lack of consistency in neuro examination; eg.pt may blink, respiration may quicken to stimulation, lack of constant visual following of objects
* EEG- minimal/no change in EEG activity during & after stimulating the patient(i.e no desynchronization)
* Lesion- diffuse cerebral injury, thalamic injury(medial and ventromedian nuclei) & caudal midbrain lesions

Locked-in state
* De-efferented state- patient is alert & aware of environment + quadriplegia+ lower cranial nerve palsy. The only way the patient responds is by vertical gaze & blinking.
* Lesion- involves motor pathways- CS tract, corticobulbar & cortico pontine pathways with sparing of somatosensory pathways & ARAS. The most common site is the ventral pons

Akinetic mutism
* It is a state of altered behaviour where alert appearing patients are silent, inert & profoundly apathetic. They lack psychiatric drive or impulse to action & are doubly incontinent. They usually lie with eyes opened and retain cycles of self-sustained arousal
* Lesion- B/L anterior frontal lobe- this leaves intact motor & sensory pathways

Thanks to Dr Ishaq M for contributing this wonderful article.