Dissociation of anosognosia and phantom movement during the Wada test

Patients who misperceive that they are moving their paralysed arm (phantom movements) may not recognise its weakness. Therefore, the relation between phantom limb movements and anosognosia for hemiplegia during selective right hemispheric anaesthesia (the Wada test) was examined.

Nine patients with intractable epilepsy underwent the Wada test. During the right hemispheric injection, after the onset of hemiparesis, anosognosia was assessed by asking patients if they were weak. The patient's vision was limited such that they could not see the position of their limbs. Phantom movements were tested for by asking patients to attempt to lift their left upper limb, and to demonstrate their left limb's position by placing their right limb in the same position as their left. Proprioception was tested by lifting the patient's paretic upper limb and having patients demonstrate this position by lifting their right limb to the same position.

Three patients experienced left phantom limb movements, and five were anosognosic for their hemiplegia. However, phantom movement occurred in only one patient with anosognosia. The other two patients with phantom movement were without anosognosia. The patient with phantom movement and anosognosia had impaired proprioception. The two patients with phantom movement but without anosognosia had intact proprioception.

Phantom movement in the presence of a proprioceptive deficit could contribute to anosognosia. However, anosognosia and phantom movement are dissociable; therefore phantom movement cannot alone account for anosognosia. Because phantom movement occurred with and without proprioceptive deficits, proprioceptive loss is not a prerequisite for phantom movement.