IVIG versus Plasma Exchange in Acute Myasthenic Crisis with Autonomic Instability
A single patient in the ICU with myasthenic crisis and a swinging blood pressure. The disagreement isn't the same as the drug-selection question in Guillain-Barré syndrome — it's a distinct acute setting where a planned thymectomy and active hemodynamic instability pull in opposite directions.
N.T., a 39-year-old high school chemistry teacher, called her neurologist's after-hours line eighteen hours ago because breathing felt, in her words, "like trying to inhale through a straw that keeps getting narrower." Generalized myasthenia gravis has been reasonably controlled for the two years since her diagnosis, well enough that she rarely thought about it outside her twice-daily pyridostigmine, with a thymectomy already scheduled for six weeks from now. A respiratory infection the week before appears to have precipitated this crisis, and she is now in the ICU on non-invasive ventilatory support, her forced vital capacity down to 45% predicted and still trending downward. Her husband, sitting at the bedside, keeps asking how a cold turned into this. What's complicating the immediate treatment decision isn't her myasthenia itself — it's her vitals: her blood pressure has swung from 88 over 54 to 168 over 98 within the past six hours, with intermittent sinus tachycardia, a real autonomic instability layered on top of the crisis itself.
Both IVIG and plasma exchange are reasonable acute treatments for myasthenic crisis, and neither guideline evidence nor practice consensus names one as clearly superior. Gajdos and colleagues randomized 87 patients in myasthenic exacerbation to plasma exchange or IVIG in 1997 and found no significant difference in muscular score at day 15 — but did record markedly more adverse events in the exchange arm, eight against one. Some centers favor PLEX specifically ahead of a near-term planned thymectomy, reasoning that its faster clearance of circulating antibody better prepares a patient for surgery than IVIG's somewhat slower onset. But PLEX requires central line placement, which N.T. doesn't yet have, and apheresis itself involves real intravascular volume shifts — exactly the kind of hemodynamic stress her current blood pressure swings make genuinely risky right now, not just theoretically so.
Faster clearance against an unstable pressure trend
I'd start PLEX. Onset of effect tends to be faster than IVIG in acute crisis, and with thymectomy planned in six weeks, some centers specifically favor PLEX ahead of surgery because it clears circulating autoantibody more quickly — getting her stabilized and closer to her surgical timeline in one move rather than two separate treatment decisions.
I hear the onset-speed argument, and in a hemodynamically stable patient I might agree with it. And I'd point at the tolerability side of Gajdos specifically: the trial that found the two equivalent on efficacy also found nearly all its adverse events concentrated in the exchange arm, which is not a detail I can set aside in this patient. N.T.'s blood pressure has swung from 88 over 54 to 168 over 98 in the past six hours — that's active autonomic instability happening right now, not a theoretical risk factor on a chart. Placing a central line and then running apheresis, with its real intravascular volume shifts, in a patient whose pressure is already this labile is asking for a hemodynamic event on top of a respiratory crisis we're still actively managing.
I'd start IVIG through her existing peripheral access instead — it doesn't require a new central line or subject her to apheresis-related volume shifts while she's this unstable, and it treats the same crisis without adding a second acute risk to manage simultaneously.
I don't think these positions are actually in conflict once you put them in sequence rather than treating this as a single either-or choice. Start IVIG now, through her peripheral line, given the immediate hemodynamic risk — that addresses the Neurointensivist's genuine concern without giving up on stabilizing her.
Then reassess in 48 to 72 hours: if her respiratory status hasn't improved adequately, or if the thymectomy timeline genuinely requires the faster antibody clearance PLEX offers, we revisit it once her blood pressure has settled and central line placement is a lower-risk decision than it is today.
Resolved for the acute period: IVIG started via her existing peripheral access, with a planned 48-to-72-hour reassessment of respiratory status and blood pressure stability before any decision about PLEX or central line placement.