Ultrasound-guided injection of the iliopsoas muscle with botulinum toxin in camptocormia
Background: Camptocormia is characterized by an abnormal posture of the trunk with pronounced flexion of the thoraco-lumbar spine, which increases during walking and abates in the recumbent position, consistent with a primary action dystonia of the spine. Therapeutic efforts to alleviate this debilitating, mostly Parkinson's disease (PD)-associated symptom, have been mostly futile. Injection of botulinum toxin A (BtA) into the rectus abdominis muscle has been beneficial only in a small subgroup of patients with palpable dystonic contractions of the abdominal wall.
Methods: As a novel therapeutic approach, we treated four patients with PD-associated camptocormia with ultrasound-guided injection of BtA (Dysport®) into deep portions of the iliopsoas muscle. Two patients with pure forward flexion of the trunk received bilateral injections, and two patients who presented with marked trunk deviation to one side (“Pisa syndrome“) received unilateral (i.e. ipsilateral) injections. Starting from 500 U of BtA per side, the dose was increased by 500 U in 3- to 4-month intervals up to 1,500 U per side, or until side effects occurred. Outcome was evaluated at 2, 4 and 12–16 weeks after each treatment by a detailed interview, physical examination, and by measuring the height for quantitative assessment of posture.
Results: Treatment was generally well tolerated, with a transient inguinal itching and painful sensation in one patient as the only local complication at the injection site. At the initial dose, two patients reported a transient and moderate improvement of posture within a few days after injection. At the highest dose, two out of four patients complained of weakness of hip flexion (e.g. when climbing stairs or tying shoes), and one experienced significant worsening of her general condition including her posture, albeit closely associated with the passing away of a close relative. Clinical examination detected only mild to moderate hip flexor paresis. Objective assessment of posture failed to show a significant benefit at follow-up visits.
Conclusion: Injection of BtA to the iliopsoas muscle is not in itself a promising approach for the treatment of camptocormia. An appropriate target structure for BtA treatment of this severe postural disorder remains to be identified.