Disorders of consciousness (DOC) include coma, vegetative state (VS) and 
minimally conscious state (MCS). Coma is a condition of unarousability with a 
complete absence of wakefulness and awareness, whereas VS is characterized by a 
lack of awareness despite a preserved wakefulness. Patients in coma are 
unconscious because they lack both wakefulness and awareness. Patients in a VS 
are unconscious because, although they are wakeful, they lack awareness. 
Patients in a MCS show minimal but definite behavioural evidence of self and 
environmental awareness. Coma results from diffuse bilateral hemispheric lesions 
or selective damage to the ascending reticular system (which is functionally 
connected to the cerebral cortex by intralaminar thalamic nuclei). VS is a 
syndrome that is considered to be the result of a disconnection of different 
cortical networks rather than a dysfunction of a single area or a global 
reduction in cortical metabolism. As revealed by functional imaging studies, 
clinical recovery is often associated with a functional restoration of 
cortico-thalamo-cortical connections. Depending on the amount of network 
restored, patients may regain full consciousness or remain in a MCS. Molecular 
and neural mediators may indirectly contribute to the above restoration 
processes owing to their role in the phenomenon of neural synaptic plasticity. 
Therefore, there is growing interest in the possible effects of drugs that act 
at the level of the CNS in promoting emergence from DOC. Sporadic cases of 
dramatic recovery from DOC after the administration of various pharmacological 
agents, such as baclofen, zolpidem and amantadine, have been recently supported 
by intriguing scientific observations. Analysis of the reported cases of 
recovery, with particular attention paid to the condition of the patients and to 
the association of their improvement with the start of drug administration, 
suggests that these treatments might have promoted the clinical improvement of 
some patients. These drugs are from various and diverging classes, but can be 
grouped into two main categories, CNS stimulants and CNS depressants. Some of 
these treatments seem to directly encourage a consciousness restoration, while 
others play a more determinant role in improving cognitive domains, especially 
in patients with residual cognitive impairment, than in the field of 
consciousness. Given the great interest recently generated in the scientific 
community by the increasing number of papers addressing this issue, further 
investigation of the above treatments, with particular attention paid to their 
mechanisms of action, the neurotransmitters involved and their effects on 
cortico-thalamo-cortical circuitry, is needed.