Procerus sign in progressive supranuclear palsy and corticobasal degeneration.

The procerus sign was described by Romanoand Colosimo (1) in two patients with progressive supranuclear palsy (PSP), being defined as the appearance of vertical wrinkles in the glabellar region and the bridge of the nose due to dystonic contractions of the procerus muscle, associated with a combination of reduced blinking, spasticity, lid retraction, and gaze palsy. This occurs because the procerus muscle originates in the nasal bone and inserts in the skin in the center of the forehead between the eyebrows (1). Recently, two letters (2, 3) have been published suggesting that the name"procerus sign" is erroneous, because the vertical wrinkles in the forehead are not formed by contractions of the procerus muscle, but rather by those of the corrugator supercilii muscle. The procerus muscle acts by drawing down the medial angle of the eyebrows, producing the transverse wrinkles over the bridge of the nose. The reply from Romano and Colosimo (4) was as follows: the peculiar contractions of the upper facial muscles in PSPpatients are complex and not easily explained by simple contraction of the procerus muscle, where the corrugator supercilii and orbicularis oculi muscles are also involved. They stated that their aim was not to detail the complex anatomy of the muscles involved in the human facial expression, but simply to draw attention to a distinctive semiological aspect of PSP using the procerus sign, thus with no need to withdraw the nameof the procerus sign (4). Are the peculiar facial expressions with vertical wrinkles in the forehead associated with "astonished", "worried" or "reptile-like" features, specific to PSP? Warabi et al (5) have recently reported similar features in a patient with clinically diagnosed corticobasal degeneration (CBD).