Does intravesical application of botulinum toxin lead to systemic muscle weakness? An approach to an uro-geriatric problem

Abstract

Muscle weakness after botulinum toxin injection into the detrusor muscle due to refractory overactive bladder is reported by approximately 10 % of patients in clinical studies. This could further aggravate the risk of falls in geriatric patients. For the first time, the potential problem of muscle weakness after urologic treatment with botulinum toxin was to be investigated by a geriatric assessment (hand grip measurement). In a prospective study design, hand grip was measured before and three months after botulinum toxin injection into the urinary bladder in a dose of 100 - 200 MU. The measurement was performed with the usual hand grip device by pressing the pressure gauge three times with the dominant hand. Relevant muscle weakness was assumed if hand grip was reduced by more than 20 %. The measurement of 100 patients was intended. In an interim analysis of 53 patients with an average age of 65.25 ± 13.99 years, the decrease in hand grip was + 0.00 ± 0.06 kPa or -0.13 ± 1.69 %. In patients receiving 100 MU of botulinum toxin, the decrease was +0.01 ± 0.06 kPa or -0.29 ± 1.64 %; after injection of 200 MU, it was 0.02 ± 0.06 kPa or 0.720 ± 1.77 %. The changes were neither significant for the overall population nor for the differences between the dosage groups. Therefore, the study was terminated. The results of the hand grip measurement performed after botulinum toxin injection into the detrusor muscle demonstrated for the first time that there is no loss in hand grip as a possible indicator of muscle weakness and a risk of falls after urologic treatment with 100 MU or 200 MU. Accordingly, the botulinum toxin injection due to refractory overactive bladder seems to be safe for geriatric patients.