Cradling the telephone between the head and shoulder during a lengthy conversation can be hazardous to one's health.
A case report in the November 10 issue of Neurology described the experience of a 43-year-old French psychiatrist who held the telephone receiver between his left ear and shoulder to keep his hands free while talking with a patient for more than an hour. Shortly after the call he experienced temporary blindness in his left eye, pulsed ringing in his left ear, and difficulty speaking.
Voelker R. "Mini-Stroke" From Phone Call. JAMA. 1999;282(22):2111. doi:10.1001/jama.282.22.2111-JWM90010-3-1