I don't like referring to something so unpleasant and uncomfortable by such a silly name. Is there a proper medical term for this phenomenon?
In the literature, they're referred to as shock-like paresthesias and less commonly, Lhermitte's sign (pronounced Ler-meets).
However, the phenomenology of Lhermitte's sign is a little bit different to brain zaps and is typically seen in multiple sclerosis.
From The SSRI discontinuation syndrome:
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\hspace{0.5cm}Sensory\text{ }abnormalities.\text{These include paraesthesia (i.e.}\\
\hspace{0.5cm}\text{tingling) and numbness, also described with TCA discon-}\\
\hspace{0.5cm}\text{tinuation but less prominent, and brief ’electric shock-like’}\\
\hspace{0.5cm}\text{sensations which appear unique to SSRI and venlafaxine}\\
\hspace{0.5cm}\text{termination (Louie et al., 1996). The shocks may be}\\
\hspace{0.5cm}\text{experienced as ’electrical sensations’ (Rosenstock, 1996)}\\
\hspace{0.5cm}\text{running through the head, upper body, arms or legs or as}\\
\hspace{0.5cm}\text{intense internal sensations within the head, for example a}\\
\hspace{0.5cm}\text{’slamming’ within the head (Mallya et al., 1993), a ’whooshing}\\
\hspace{0.5cm}\text{noise’ or a ’rush’ one could ’almost hear’ (Berlin, 1996).}\\
\hspace{0.5cm}\text{Sometimes they are exacerbated by movement, particularly of}\\
\hspace{0.5cm}\text{the head, and are associated with brief bursts of dizziness}\\
\hspace{0.5cm}\text{(Frost and Lal, 1995). Ellison’s (1993) description of bursts of}\\
\hspace{0.5cm}\text{dizziness as a ’jolt’, ’rush’, ’shock’, or ’buzz’ also suggests an}\\
\hspace{0.5cm}\text{overlap between shocks and dizziness.} \colorbox{yellow}{Coupland et al. (1996)}\\
\hspace{0.5cm}\colorbox{yellow}{regarded the shocks as a severe form of paraesthesia and}\\
\hspace{0.5cm}\colorbox{yellow}{emphasized that they were distinct from anything patients had}\\
\hspace{0.5cm}\colorbox{yellow}{experienced before.}\\
\hspace{0.5cm}\text{Shocks have occurred following discontinuation from}\\
\hspace{0.5cm}\text{sertraline (Rosenstock, 1996), paroxetine (Frost and Lal,}\\
\hspace{0.5cm}\text{1995; Dominguez and Goodnick, 1996), fluoxetine (Berlin,}\\
\hspace{0.5cm}\text{1996) and fluvoxamine (Mallya et al., 1993).} \colorbox{yellow}{Reeves and}\\
\hspace{0.5cm}\colorbox{yellow}{Pinkofsky (1996) reported a paroxetine discontinuation}\\
\hspace{0.5cm}\colorbox{yellow}{reaction in which shocks were consistently elicited by neck}\\
\hspace{0.5cm}\colorbox{yellow}{flexion. They proposed that the sensations constituted}\\
\hspace{0.5cm}\colorbox{yellow}{Lhermitte’s sign i.e. a neurological sign that usually indicates}\\
\hspace{0.5cm}\colorbox{yellow}{spinal cord disease.}\\
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