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
College Answer
|
Syndrome |
Features |
Site of lesion |
|
Locked-in |
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 |
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 |
Extensive damage to both cerebral |
|
Akinetic |
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.
| 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 manual: Chapter 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.