Phenomenology and neural correlates of implicit and emergent motor awareness in patients with anosognosia for hemiplegia.

Anosognosia for hemiplegia (AH) is characterized by a lack of awareness of motor disorders and appears associated with fronto-temporal-parietal damage. Neuropsychological evidence indicates that behavioral indices of residual forms of motor awareness may co-exist with explicit denial of impairment. Here we explore whether the attempt by AH patients to perform an action may disclose residual forms of motor awareness and whether such forms are underpinned by different neural structures. Twelve hemiplegic patients affected by AH were tested in tasks assessing: (i) implicit awareness (IA), indexed by discrepancies between verbal reports and actual motor behavior; (ii) emergent awareness (EA), indexed by increased verbal awareness induced by the attempt to perform actions. IA and EA were found in five and three patients, respectively. Lesion analysis indicates that while the lack of IA is associated with damage to subcortical white matter anterior to the basal ganglia, lack of EA is linked to damage to cortical regions including insulo-frontal, temporal and parietal structures. Our results indicate that deficits in explicit and implicit awareness are associated with lesions involving different cortico-subcortical structures. Moreover, the results show that the attempt to perform an action may ameliorate body awareness deficits and have implications for rehabilitation.

Intrathecal baclofen withdrawal syndrome caused by low residual volume in the pump reservoir: a report of 2 cases.

Intrathecal baclofen (ITB) is an effective treatment for spasticity caused by spinal or cerebral pathologies. Severe withdrawal symptoms can result, however, if ITB is abruptly withdrawn as a result of equipment malfunctions or human error. We describe 2 cases of severe ITB withdrawal syndrome. In the first case, the symptoms appeared 5 months after pump placement, when residual volume was 2.0 mL; in the second case, symptoms appeared 2 months after the replacement of a new pump, when residual volume was 0.9 mL. In both cases, there was no evidence of system malfunction or human error. The syndrome occurred from up to 72 hours before the scheduled refilling procedure, and the residual volume in the Medtronic SynchroMed EL pump reservoir was either at, or significantly lower than, the recommended 2 mL. These cases suggest that the SynchroMed EL pump reservoir should be refilled, to avoid potentially serious consequences, when the residual volume is not lower than 3 mL by programming the alarm to sound at a volume larger than the recommended 2 mL.