Discussion
In this paper, we shared a case of acute pulmonary complication that
resulted in the need for intensive care and intubation on the third day
after treatment of focal spasticity with BoNTA in a patient with CPM.
When we examined the literature in terms of BoNTA-related pulmonary
complications, we found that Oliver et al. published clinical
correspondence in 2018, in which they described a gradual decrease in
pulmonary function over time, which returned to normal after BoNTA
discontinuation during long-term treatment of migraine (11). We did not
see any case in which pulmonary involvement developed in an acute
dramatic manner as in our case. In addition, a multicenter study
conducted in 2006 investigating the pulmonary effect of BoNTA reported
that this treatment was safe without pulmonary complications (12).
It is known that after BoNTA applications, respiratory failure may
develop due to paralysis of the respiratory muscles, which may result in
death. In our case, we initially considered the paralysis of the
respiratory muscles since the patient worsened approximately 72 hours
after the BoNTA injection. Pulmonary involvement was not expected at
first, and it was thought that the respiratory muscles were likely to be
affected by toxins and that a tracheostomy would probably be required.
However, the presence of bilateral consolidation in the lungs and areas
of infiltration of ground-glass opacity on the thoracic CT taken during
the intensive care period further complicated the case by revealing that
the situation was not actually expected based on our knowledge that
systemic complications associated with BoNTA therapy were uncommon and
such an acute pulmonary complication had never been encountered before.
However, the radiological findings on thoracic CT being interpreted in
favor of ARDS, clinical indications, and absence of any other condition
that could explain the etiology supported the possibility of a
BoNTA-related pulmonary complication.
In a study in which the intranasal administration of BoNTA-related
pulmonary involvement was evaluated in mice, some histopathological
changes were detected in the lungs despite the protection of the animals
against neurotoxic effects. Although this situation was not considered
to be direct toxin poisoning, it was suggested to have occurred with
alveolar hemorrhage due to pulmonary capillary endothelial injury caused
by a secondary cytokine-mediated inflammatory reaction triggered by the
toxin, which led to the development of interstitial edema (13).
Similarly, in two studies, Ermert et al. observed widespread endothelial
weakening in the electron microscopic examination of the lungs of
rabbits poisoned with botulinum toxin c2 and found edema formation due
to increased permeability in pulmonary capillaries (14,15).
In the retrospective evaluation of our patient, the ground glass
opacities observed in the thoracic CT scan, rapid improvement in her
clinical state according to the laboratory findings, and increased
pulmonary capillary permeability and endothelial damage due to BoNTA and
other toxin types reported in animal experiments in the literature
primarily suggested that our patient developed an acute pulmonary
complication in which pulmonary edema was seen due to increased
capillary permeability associated with BoNTA.