LAUSR

We greatly appreciate Dr. Blomstedt's comments about our recent article describing two patients with reproducible hyperhidrosis after subthalamic nucleus deep brain stimulation (STN-DBS) in Parkinson's disease (PD) [1]. Importantly, his experience regarding the occurrence of hyperhidrosis after DBS, specifically with posterior subthalamic area (PSA) neurostimulation greatly contributes to a better understanding of the anatomical distribution of thermoregulatory tracts in humans. The PSA is an anatomical term that includes several closely related structures including the caudal Zona incerta (cZi), the prelemniscal radiation (Raprl) and pallidothalamic white matter tracts (fields of Forel H1, H2) [2]. The PSAborders are defined by ananterior apex that lies lateral to the hypothalamus and periaqueductal graymatter, posterior and medial to the STN and internal capsule, anterior to the tegmental area, medial lemniscus and lateral to the Red nucleus (Rn). There is limited data regarding the anatomical and functional characteristics of central thermoregulatory pathways in humans. After publication of our article describing two patients with DBS induced hyperhidrosis [1], we learned that Dr. Blomstedt and Fytagoridis briefly reported one additional case in a general review of PSA complications [3]. Dr. Blomstedt's experience emphasizes the close anatomical relationship between autonomicfibers and the tremor suppressing area in the PSA. Stimulation of contacts used for chronic tremor control induced hyperhidrosis only at higher voltages. Interestingly, his observations in nine patients confirm experimental data showing that decussation of autonomic descending fibers follows a segmental pattern rather forming fiber bundles accounting for bilateral effects [4] except in one patient. The reasons behind ipsilateral sweating in this patient are unclear. We agree with Dr. Blomstedt's comments regarding anatomical localizations of DBS leads in other previously reported cases. However, the contact responsible for hyperhidrosis in our first patient although located medially between subthalamic nucleus and Rn, it was in a more anterior location (0.46 mm posterior) in relationship to the midcommissural point (MCP). Typical cZi coordinates are 14.0 ± 1.56 mm lateral, 5.8 ± 1.46 mm posterior and 2.1 ± 1.05 mm below the MCP [5]. The mean