We received a consult to evaluate for “abulia vs akinetic mutism”. You may be unfamiliar with these terms. Here is a brief overview:
Definition
Akinetic mutism is the most severe presentation along a spectrum of disorders affecting motivation and initiation.
Least severe Apathy –> Abulia –> Akinetic mutism Most severe
These patients have the ability to think, move, and speak. But they lack the drive to initiate.
-Where they land on the spectrum depends on their degree of impairment.
- Apathy: Low motivation but still functions independently
- (apathy = nonspecific term and has broader implications than abulia and akinetic mutism which often hint at specific dysfunction in brain circuits as below)
-Abulia: Marked decrease in initiation, needs prompting to act
-Akinetic mutism: Near-complete lack of movement (akinesia) and speech (mutism)
-Initiation is essentially absent, despite prompting
Akinetic mutism is a SYNDROME. When you identify it, you need to investigate its etiology. The term alludes to dysfunction in frontal-subcortical circuits.
Similarly, making a diagnosis of abulia is hinting at dysfunction in frontal-subcortical circuits.
-Usually made in the context of neurologic illness (ie stroke, TBI, neurodegeneration).
Supportive features in diagnosis of akinetic mutism:
-Confirm wakefulness
-Confirm that capacity to move and speak is intact
-Demonstrate lack of spontaneous speech and movement
-Look for stimulant-induced activation (“telephone effect” – they will suddenly answer the phone with a sudden, abrupt stimulus)
-Check affect (minimal distress, different than depression)
-Check history:
-Hx of frontal lobe lesion, basal ganglia/thalamic stroke, hydrocephalus
-Imaging supporting frontal-subcortical involvement
Differential Diagnosis/Possible Causes of Low Motivation:
-Neurologic
-Lesions involving frontal lobe, basal ganglia, thalamus, white matter
-Medication-related
-Dopamine blockade (antipsychotics), sedatives
-Neurodegenerative
-Parkinson’s, Alzheimer’s, Frontotemporal dementia
-Psychiatric
-Depression (however in depression, will want to act, but are unable. In abulia, there is no drive)
-Medical/systemic
-Delirium, endocrine disorders
Other differentials:
-Catatonia
-Minimally conscious state
-Locked-in syndrome
Pathophysiology:
–Failure of frontal-subcortical motivation circuit.
-Problem at any of the “nodes” within the circuit.
-Key locations:
-Anterior cingulate cortex (ACC)
-Striatum
-Globus pallidus (GPi)
-Thalamus
-This leads to loss of Dopamine-driven “energizing signal” –> over-inhibition of thalamus (via GPi) –> decreased frontal activity –> decreased initiation of behavior and speech
-Akinetic mutism (AM) = network disconnection syndrome (not a single lesion problem)
Treatment:
-Treat underlying cause (stroke, tumor, hydrocephalus, etc)
-Possible meds:
-Dopamine-based
-Bromocriptine, levodopa
-Stimulants/frontal activation
-Methylphenidate
-Atomoxetine
-Zolpidem (diagnostic and therapeutic)
Gator Psychiatry 