Beth Peterson Smith

Dose‐ and volume dependent‐response to intramuscular injection of botulinum neurotoxin‐A optimizes muscle force decrement in mice

Botulinum neurotoxin‐A (BoNTA) is a potent neurotoxin used to alter muscle tone to manage spasticity and to provide tendon bioprotection; however, the appropriate dose and injection volume to administer is not defined. Male mice (n = 120) received BoNTA injections into one gastrocnemius with either a constant volume (10 µl) with a variable dose (1, 3, 6 U/kg) or a constant dose (3 U/kg) in a variable volume (2.5, 5, 10, 20, 30 µl). Electromyographic (EMG) examination, muscle force generation (MFG), and wet muscle mass were measured in the ipsilateral and contralateral limbs at 1, 2, 4, or 12 weeks post‐injection. MFG and EMG responses decreased to approximately 40% of contralateral after a 1 U/kg injection and 0% of contralateral by 3 and 6 U/kg injection at 1 week after injection. Neuromuscular blockade was greatest with a 10 µl injection volume. MFG, EMG examination, and wet muscle mass reached contralateral values 12 weeks after injection for all injection doses and volumes tested. Effective injection doses and volumes were identified for producing full and partial neuromuscular blockade in the mouse gastrocnemius. These findings have important clinical implications in the intramuscular administration of BoNTA to manage muscle tone.

Treatment of Palmar Hyperhidrosis With Botulinum Neurotoxin A

i s t p t i PALMAR HYPERHIDROSIS IS a type of primary hyperhidrosis, defined as excessive sweating in localized areas in the absence of an associated systemic disorder. This disorder of eccrine sweat glands affects between 1% and 3% of the population, including men and women of all ethnicities equally, with a strong hereditary component demonstrated by the fact that most affected individuals have a positive family history. It can be a debilitating condition, affecting patients both physically and psychologically. Severe palmar hyperhidrosis disturbs mechanical grip function and often impairs physical contact with others, which may have profound personal and professional consequences. When associated with spasticity and a closed fist, or under a cast or splint, hyperhidrosis may contribute to maceration, loss of skin integrity, and ulcers or infection. This article reviews the evaluation, management, and treatment of primary palmar hyperhidrosis, with an emphasis on the therapeutic use of botulinum neurotoxin type A (BoNT-A). Initial evaluation of a patient with palmar hyperhidrosis should include a detailed history focusing on exacerbating factors such as heat or emotional stress, and the severity of the associated psychological, social, and professional disability. An age-appropriate history and physical examination should also be performed to evaluate for possible causes of secondary hyperhidrosis, which include but are not limited to endocrinologic abnormalities (hyperthyroidism), neoplasms (carcinoid tumors and pheochromocyto-