Finger agnosia is a type of tactile agnosia, in which there is inability to identify which finger has been touched when the eyes are closed, despite knowing that a finger has been touched; or inability to point to or move a finger when it is named; or inability to name the fingers (patient’s own fingers or those of another person). This is a disorder of body schema, and may be regarded as a partial form of autotopagnosia.
Finger agnosia is most commonly observed with lesions of the dominant parietal lobe. It may occur in association with acalculia, agraphia, and right-left disorientation, with or without alexia and difficulty spelling words, hence as one feature of Gerstmann syndrome. Isolated cases of finger agnosia in association with left corticosubcortical posterior parietal infarction have been reported. Since this causes no functional deficit, it may be commoner than reported.
Della Sala S, Spinnler H. Finger agnosia: fiction or reality? Archives ofNeurology 1994; 51: 448-450