BPC van de Warrenburg, KP Bhatia, NP Quinn. Pisa syndrome after unilateral pallidotomy in Parkinson’s disease: an unrecognised, delayed adverse event? J Neurol Neurosurg Psychiatry 2007;78:329–330.

The authors of this letter would like to correct the statement that “… postoperative imaging in these three patients confirmed that the lesions were confined to the medial pallidum…” Upon further subsequent expert review of the postoperative MRI scans, it became apparent to the authors that although the medial pallidum was indeed successfully lesioned in all three patients, in each of them the lesion was in fact more extensive. In patient 1, the surgical lesion extended into the external globus pallidus and putamen; in patient 2 into the internal capsule; and in patient 3 into the external globus pallidus, with lesions further rostrally into the area of the sella media. Nevertheless, the key issue of whether the Pisa syndrome in these patients was related solely to their advanced stage Parkinson’s diesease or to the surgical lesion in the medial pallidum (and beyond) remains unsettled. Therefore, the authors’ invitation to report on the very long-term follow-up of pallidotomy patients in relation to the localisation of the surgical lesion still stands. The authors apologise to the readership for this unfortunate and unintended error.