Cortical stimulation had also practical implications in neurosurgery and became increasingly selleckbio important during epilepsy surgery. Fedor Krause (1857�C1937), the pioneer of the German neurosurgery, and the neurologist and neurosurgeon Otfrid Foerster (1873�C1941) from Breslau, Germany, used the cortical electric stimulation to localize intraoperatively the epileptic foci by provoking an aura or a typical epileptic fit [20�C22]. This electrical stimulation was superior to focus localization based merely on anatomical landmarks. The knowledge of the localization of the eloquent cortical areas had also a very practical consequence for neurosurgery. At the end of the 19th century, two Swiss professors of surgery Rudolf Ulrich Kr?nlein (1847�C1910) [23, 24] in Zurich and Theodor Kocher (1841�C1917) [25, 26] in Bern developed independently a method to localize the underneath situated central sulcus and the Sylvian fissure on the scalp.

Kr?nlein used for this a construction of two parallel horizontal and three vertical supporting lines which were based on external bony landmarks (Figure 2) [23]. These lines allowed defining and localizing the position and extension of the central sulcus on the scalp or on the sagittal X-ray image. These supporting lines and the lines representing the central sulcus and the Sylvian fissure in form of ribbons could be also pulled over the head. They marked on the scalp the position of these intracranial structures [24]. The device was called craniometer.

In contrast to Kr?nlein, Kocher’s craniometer was based on cadaver studies and consisted of elastic ribbons which were arranged and fixed on the head in a way that the ribbons were just beyond the central sulcus. The elasticity of this craniometer had the advantage that the ribbons preserved their relative position independently of the size of the head. Kocher already described this method in 1892 in his book Lessons in Operative Surgery [25, 26]. Figure 2 Kr?nlein’s construction of the central region and the Sylvian fissure based on external anatomical landmarks. The horizontal inferior orbitomeatal line is the base line. The parallel supraorbital line marks the inferior border of the central region … A more general approach to the problem of localization of cortical structures was developed by the anatomist Dimitri Zernov (1843�C1917) [27] and his pupil Nikolay Altukhov [28] at the end of Dacomitinib the 19th century in Russia. Zernov called his device an encephalometer. It was a head ring, which was fixed to the patients skull [29, 30]. The basic idea was to understand the head approximately as a terrestrial globe (Figure 3). Every point at the surface of the head was defined similar to the globe by polar coordinates expressed in degrees of latitude and longitude.