Hemispatial neglect

To the Editor: We recently reviewed “Hemispatial neglect dected by non-neglected stimuli” by Market al .1 The concept is an intriguing one and worthy of investigation. The hypothesis that the authors wiehed to test waa that patients either cannot disengage from, or are overattracted to, stimuli in the non-neglected field. They defined neglect as an omission of 2 or more targets to the left of the midline in a cancellation task, and identified 10 subjecta who met this criterion. They then tested thew subjects with 2 additional cancellation task.91 in which targets were erased and 1 in which the targeta were drawn over. They found that a total of 298 targeta were neglected in the drawing-over task and that only 87 were neglected in the erasure task. From this, they concluded that the amount of neglect waa related to the presence or absence of targets in the non-neglected field. After reviewing their paper, we find it difficult to reach this conclusion on the h i s of the data provided. Becauae of the wide variability in the lesion sites, the wide range in time from injury, and the absence of a description of the patienta’ clinical state (in particular, reference to gaze preferences, hemianopias, dementia and, especially, level of consciousness), we find it difficult to accept the premiae that the screening test waa measuring the same phenomenon in all the subjects. In addition, during the testing phase, patients 1, 4, and 9 failed to meet the screening criterion, which casts doubt on the reliability of this screening test. Perhaps moat remarkable, thoee patienta greater than 65 years of age (2,5,7,8, and 10) accounted for 359ofthe385miseedtargets,whereaathoseyoungerthan65 (1,3,4,6, and 9) accounted for only 26 of the missed targeta. This raiees the question of whether this is an age-dependent phenomenon related, perheps, to dementia rather than neglect. All of the foregoing points out the need for comparison or control group to 888e88 the effects of lesion site, time from injury, clinical state, and age on the results of these teets. More generally, it demonstrah the necessity for proper comparison or control groups in any clinical trial, without which the data are bound to be difficult to interpret. Thus, we remain where we began: with an interesting hypothesis that still requires appropriate investigation.