The American Academy of Neurology, in conjunction with the American Congress of Rehabilitation Medicine, and the National Institute on Disability, Independent Living and Rehabilitation Research, updated recently the AAN 1995 practice parameter on disorders of consciousness, and its 2002 definition of minimally conscious state. The 2 reports are published in Neurology 2018, 91:450-460 and 461-470.
The first recommendation is to treat confounding conditions and withdraw confounding drugs and carry out multiple serial evaluations at times of best levels of arousal, to improve diagnosis of children and adults with prolonged disorders of consciousness. In adults, the minimally conscious state, unresponsive wakefulness syndrome and traumatic etiology have better prognosis than vegetative state, and non-traumatic. Prognostic accuracy is improved in adults by structural MRI, SPECT, and the Coma Recovery Scale-revised. In children there are no established tests. Amantidine (200-400mg daily) improves funcitonal recovery in some traumatic cases in the 4-16 week period after onset.
These recommendations apply when patients have achieved a stable state of disorders of consciousness. When there is continuous ambiguity about the evidence of the presence of conscious awareeness, in spite of repeated behavioural assessments, neurophysisiological assessments may clarify the situation. In the first 28 days postinjury clinicians should avoid statements of a universally poor prognosis. Serial clinical evaluations help in establishing the directions consciousness is evolving. At 2-3 months postinjury the P300 auditory evoked response and the EEG are of proven value in conjuntion with MRI good enough to asess corpus callosum, dorsolateral upper brainstem and corona radiata lesions. The SPECT scan may be carrried out at 1-2 months postinjury. BOLD functional MRI shows activation of the auditory cortex with familiar voices. All these tests help predict the final state at 12 months.
The term “permanent” in disorders of consciousness should be substituted for chronic, given that many non-traumatic recover at 3 months, and traumatic at 12 months. After these times it is still useful to use “chronic”, but the state may be permanent. Some late recovery cases may be related to imprecise diagnosis, and cognitive-motor dissociation. The later has sometimes been called “unaware wakefulness syndrome”, a denomination that does not seem to be any better than “vegetative state”. Pain precautions are mandatory in all cases, because of the possibility of covert consciousness.
Dr Paulo Bittencourt
