Thompson says that after eight years of administering Botox therapeutically, he hasn't "had any patient with serious adverse reaction," and that the "incidence of side effects is very, very low."
"I don't believe her seizures were made worse by the Botox," said Thompson, who was not involved in treating Kristen, noting that patients with cerebral palsy are already at increased risk for pneumonia and Botox may not have contributed to contracting it.
"Properly dosed and diluted, botulinum toxins should not induce systemic side effects" such as breathing difficulties, adds Dr. Maurice Sholas, practice director of Rehabilitation at Children's Healthcare of Atlanta.
"I've been injecting patients with Botox for 12 years," says Garrett. "Patients are aware of potential side effects, [but] by and large, Botox has been proven to be very safe."
And Allergan fully endorses their safety record. Muilenburg notes that Botox is "one of the most widely researched medicines in the world" and Botox sponsors affirm that the toxin is "safe" and "effective".
But Spears' would beg to differ.
According to court documents, independent research has identified 16 deaths, 87 hospitalizations, and 180 cases life-threatening conditions associated with Botox injections, not including the death and injury claims that will be brought to court in this case.
"I don't want this to happen to anyone else's child," Spears said in a statement to the court, according to the Los Angeles Times.
"All drugs have potential side effects and one side effect of Botox is that it can, on occasion, migrate from the injection site, to other muscle groups," notes Besser. "When this hits the respiratory muscles, it can make breathing difficult."
This rare side effect, along with paralysis of the muscles needed for swallowing are particularly relevant for Kristen's case, notes Sholas, and he says that if the patient was given too much of the medication or to potent a dose, these side effects could have occurred.
Kristen's pediatrician, Dr. Pia Habersang testified that she gave Kristen 15 units of Botox per kilogram of the child's weight, reports the L.A. Times and Sholas and Thompson both say that this dosage is on the high end but still considered a reasonable dose for this condition.
However, Kristen required hospitalization 10 times for repeated bouts of breathing and swallowing difficulties in the months of her Botox treatment, according to a motion in court, the L.A. Times reported.
"Whether or not Botox played a role remains to be seen," says Garrett, who was also not involved in treating Kristen. but the take home message here is "to make sure patients or their parents are aware of this rare side effect and that they seek treatment immediately if there is any respiratory difficulty," adds Besser.
"People have to understand [that] no medication is 100 percent safe," says Thompson.
But Thompson also feels that it is essential that people understand the benefits this medicine can offer when used properly. "[It] provides significant benefit and can improve quality of life for kids with cerebral palsy," he says.
"We still have patients booked for and continuing to receive Botox on a regular basis. I hope that our patients for whom this is appropriate continue to use it."