Outline the important distinguishing  clinical features and  the site of lesion for the following neurological states (you may tabulate your answer).

a) Locked in syndrome (de-efferented state)

b)  Persistent vegetative state

c)  Akinetic mutism

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College Answer

Syndrome

Features

Site of lesion

Locked-in
syndrome
(de-efferented state)

Alert and aware, vertical eye movements present, and able to blink. Quadriplegic, lower cranial nerve palsies, no speech , facial or pharyngeal movements

Bilateral anterior pontine lesion

Persistent
vegetative state
(PVS) (apallic syndrome, neo- cortical death)

Previously comatose, who now appear to be awake. Spontaneous limb movements, eye movements and yawning seen. However patient inattentive, no speech, no awareness of environment and total inability to
respond to commands

Extensive damage to both cerebral
hemispheres with relative preservation of the brainstem

Akinetic
mutism
(coma vigile)

Partially or fully awake patient, immobile and silent

Lesion in bilateral frontal lobes or hydrocephalus or third ventricular masses

Discussion

A description of the various vegetable-like states is available elsewhere.

It is easy to summarise:

PVS is characterised by a preserved autonomic regulation and sleep-wake cycle, but the absence of any behavioural evidence of consciouseness. The lesion is typically diffuse, eg. severe hypoxic brain injury.

Locked in syndrome is usually caused by damage to the ventral pons, and the characteristic features are total tetraplegia and facial/oral musuclar paralysis, with preserved eye opening and vertical eye movements, in the presence of a totally intact level of consciousness.

Akinetic mutism is usually caused by bilateral frontal lobe damage, and the characteristic features are immobility and silence with preserved eye tracking. These people are not paralysed, but rather lack any volition to move.

The abovelinked summary contains a table to help discriminate between states of persistent unconsciousness, which I will reproduce below to simplify revision.

 

Clinical Features to Distinguish States of Persistent Unconsciousness
Category Chronic Coma Persistent vegetative state (PVD) Minimally conscious state Locked-in syndrome Alinetic mutism Brain death
Awareness

None

None

Some

Totally alert

Some

None

Sleep-wake cycle

None

Present

Present

Present

Present

None

Response to pain

Possibly

Possibly

Present

Only in eyes

Present

None

GCS

E1-2 M1-4 V1-2

E4 V1-2 M1-4

E4 V1-4 M1-5

E4 M1 V1

E4 V1-4 M4

E1 V1 M1

Motor function

Nothing purposeful

Nothing purposeful

Some purposeful-seeming motor behaviour

Immobile

Nothing voluntary

None

Respiration

Possibly spontaneous

Spontaneous

?

Possibly spontaneous

Spontaneous

None

EEG features

Slow wave activity

Slow wave activity

?

Completely normal

Slow wave activity

Isoelectric

PET: cerebral metabolism

Severely reduced

Severely reduced

?

Normal, except the area of the lesion

Reduced

Absent

This table, as the summary it is derived from, is based heavily on the diagnostic guidelines published in 2003 by the Royal College of Physicians.

References

 

Oh's Intensive Care manualChapter 49   (pp. 549) Disorders  of  consciousness  by Balasubramanian  Venkatesh

 

Working Party of the Royal College of Physicians. "The vegetative state: guidance on diagnosis and management." Clinical Medicine 3.3 (2003): 249-254.

 

Schnakers, C., J. Giacino, and S. Laureys. "Coma: Detecting signs of consciousness in severely brain injured patients recovering from coma."Coma Science Group, Cyclotron Research Centre University of Liege, Liège, Belgium

 

Monti, Martin M., Steven Laureys, and Adrian M. Owen. "The vegetative state."Bmj 341.c3765 (2010): 292-296.

 

Giacino, Joseph T., et al. "The minimally conscious state definition and diagnostic criteria." Neurology 58.3 (2002): 349-353.

 

Plum, Fred, and Jerome B. Posner. The diagnosis of stupor and coma. Vol. 19. Oxford University Press, 1982.

 

Smith, Eimear, and Mark Delargy. "Locked-in syndrome." BMJ: British Medical Journal 330.7488 (2005): 406.

 

Cairns, Hugh, et al. "Akinetic mutism with an epidermoid cyst of the 3rd ventricle." Brain 64.4 (1941): 273-290.