Injections were performed at a rate of 1 µl/min using a motorized syringe pump and the needle was slowly withdrawn 5 min after lesioning to minimize diffusion of toxin into the injection tract.
Complications that result from weakened muscles adjacent to the injection site are due to the diffusion of toxin to unintended muscles; this may be minimized through proper injection technique (Klein 2004; Naumann and Jankovic 2004; Batra et al 2005; Vartanian and Dayan 2005).
This cell wall reinforcement could contribute to the development of physical barriers hampering the expansion of M. pinodes within the P665 tissues or reducing the diffusion of pathogenic toxins.
Hyaluronidases in Loxosceles venom have been characterized as spreading factors, increasing the diffusion of other toxins and also contributing to the gravitational dissemination of the local reaction [ 1]. Figure 3 shows the alignment of the deduced amino acid sequence of LLAE0048C from L. laeta venom glands with known hyaluronidases from Bos taurus, Apis mellifera and Vespula germanica.
The effective forward and reverse rate coefficients are defined by [ 24– 28] (2) k f e = γ k 1, k r e = γ k − 1, where k1, k−1 are intrinsic reaction rates, k D = 4 πaD is the diffusion rate, D is the diffusivity of toxin in the extracellular space, and γ = 1/(1 + Rk1/ k D ) ≤ 1 [ 25– 27].
It has been demonstrated that the injected volume is a major factor affecting the diffusion of botulinum toxin, independently from the dose.
The choice of employing an increased concentration for the corrugator and temporalis muscles aimed to limit unwanted diffusion of the toxin to the adjacent muscles and the subsequent side effects such as ptosis.
That is why we used a higher dilution for the trapezius muscles, as well as a multipoint injection procedure, in order to increase the diffusion of the toxin within such a large muscle.
Digital pressure after the injection may also decrease the diffusion of the toxin.
The patient should not manipulate the treated area after treatment to avoid unintended diffusion of the toxin.
After entire administered of 6-OHDA, the cannula was left in place for further 5 mins for complete diffusion of the toxin and then was slowly retracted.
