Botulinum Toxin Injection for Functional Popliteal Artery Entrapment Syndrome
| Status: | Not yet recruiting |
|---|---|
| Healthy: | No |
| Age Range: | 18 - 50 |
| Updated: | 12/12/2018 |
| Start Date: | January 31, 2019 |
| End Date: | August 31, 2019 |
Can Botulinum Toxin Injection Relieve Pain and Improve Function in Patients With Functional Popliteal Artery Entrapment Syndrome?
Failure to adequately diagnose and treat patients with functional popliteal artery entrapment
syndrome (PAES) leads to continued pain, loss of function and poor quality of life for many
patients nationwide. Currently, the primary treatment for functional PAES involves muscle
resection, sometimes involving large segments of muscle, which itself can lead to functional
impairment. As such, a less invasive treatment for functional PAES is desirable. The focus of
this work is to determine whether Botulinum toxin type A (BTX-A) injections into the
gastrocnemius muscle can lessen the mechanical forces placed on the popliteal artery by the
involved muscle, thereby improving symptoms caused by impaired distal blood flow.
syndrome (PAES) leads to continued pain, loss of function and poor quality of life for many
patients nationwide. Currently, the primary treatment for functional PAES involves muscle
resection, sometimes involving large segments of muscle, which itself can lead to functional
impairment. As such, a less invasive treatment for functional PAES is desirable. The focus of
this work is to determine whether Botulinum toxin type A (BTX-A) injections into the
gastrocnemius muscle can lessen the mechanical forces placed on the popliteal artery by the
involved muscle, thereby improving symptoms caused by impaired distal blood flow.
Ten (10) patients with suspected functional popliteal artery entrapment syndrome will be
recruited for this study. Dr. Michael Fredericson will recruit patients from local sports
medicine clinics and sports teams. Equal men and women will be recruited, between the age of
18 and 50 years. This subcategory will reduce the potential of recruiting patients with
age-related confounding causes for their symptoms.
After patients have been identified as having clinical features suggestive of PAES,
confirmation of the diagnosis will involve the following in accordance with standards of
care: 1) Ankle-brachial index testing with provocative maneuvers (maximal passive
dorsiflexion and maximal active plantarflexion, treadmill running at a slope), 2) MRI
angiography with provocative maneuvers (maximal plantar and dorsiflexion).
All patients will also complete at baseline a visual analog scale (VAS) of their pain, a
lower extremity functional scale (LEFS), and lower extremity ultrasound for evaluation of
gastrocnemius muscle size.
Currently, treatment of functional PAES involves surgical intervention frequently involving
resection of the gastrocnemius muscle. As part of this study, BTX-A will be administered to
the gastrocnemius. Patients will be informed about the indications, contraindications, and
adverse events associated with BTX-A injections, and they will be informed of current
standard of care options, including surgical intervention. Written consent will be obtained.
Dr. Michael Fredericson will carefully inject BTX-A (Dysport-Ipsen Inc.) into the proximal
third of the medial and lateral gastrocnemius muscles of the symptomatic leg(s). Total dose
per leg will be 400 units, 200 per injection site. Injections will be performed with the aid
of real-time ultrasound (Sonosite, Bothwell, WA) guidance.
The premise of the intervention is that hypertrophy of the gastrocnemius muscle leads to
functional entrapment of the popliteal artery at the level of the popliteal fossa with
provocation maneuvers or exercise. By temporarily reducing muscle tone and promoting
localized atrophy through BTX-A-induced chemodenervation, this entrapment can be relieved.
The primary outcome measures for this study will be VAS scores, LEFS scores, findings of
improved blood flow on ABI with provocative maneuvers, and gastrocnemius size on ultrasound.
All patient's recruited to this study will have failed prior conservative treatment, and
therefore any improvements seen in symptoms from the BTX-A injection will be considered above
and beyond what was provided by conservative care. As such, each patient in this study design
acts as their own case control (i.e. there is no appropriate intervention and/or placebo
control group for these patients).
At 1 month, 3 months and 6 months post-injection, patients will return for clinical
examination, visual analog scale (VAS) score, a lower extremity functional scale (LEFS), and
lower extremity ultrasound for evaluation of gastrocnemius muscle size.
recruited for this study. Dr. Michael Fredericson will recruit patients from local sports
medicine clinics and sports teams. Equal men and women will be recruited, between the age of
18 and 50 years. This subcategory will reduce the potential of recruiting patients with
age-related confounding causes for their symptoms.
After patients have been identified as having clinical features suggestive of PAES,
confirmation of the diagnosis will involve the following in accordance with standards of
care: 1) Ankle-brachial index testing with provocative maneuvers (maximal passive
dorsiflexion and maximal active plantarflexion, treadmill running at a slope), 2) MRI
angiography with provocative maneuvers (maximal plantar and dorsiflexion).
All patients will also complete at baseline a visual analog scale (VAS) of their pain, a
lower extremity functional scale (LEFS), and lower extremity ultrasound for evaluation of
gastrocnemius muscle size.
Currently, treatment of functional PAES involves surgical intervention frequently involving
resection of the gastrocnemius muscle. As part of this study, BTX-A will be administered to
the gastrocnemius. Patients will be informed about the indications, contraindications, and
adverse events associated with BTX-A injections, and they will be informed of current
standard of care options, including surgical intervention. Written consent will be obtained.
Dr. Michael Fredericson will carefully inject BTX-A (Dysport-Ipsen Inc.) into the proximal
third of the medial and lateral gastrocnemius muscles of the symptomatic leg(s). Total dose
per leg will be 400 units, 200 per injection site. Injections will be performed with the aid
of real-time ultrasound (Sonosite, Bothwell, WA) guidance.
The premise of the intervention is that hypertrophy of the gastrocnemius muscle leads to
functional entrapment of the popliteal artery at the level of the popliteal fossa with
provocation maneuvers or exercise. By temporarily reducing muscle tone and promoting
localized atrophy through BTX-A-induced chemodenervation, this entrapment can be relieved.
The primary outcome measures for this study will be VAS scores, LEFS scores, findings of
improved blood flow on ABI with provocative maneuvers, and gastrocnemius size on ultrasound.
All patient's recruited to this study will have failed prior conservative treatment, and
therefore any improvements seen in symptoms from the BTX-A injection will be considered above
and beyond what was provided by conservative care. As such, each patient in this study design
acts as their own case control (i.e. there is no appropriate intervention and/or placebo
control group for these patients).
At 1 month, 3 months and 6 months post-injection, patients will return for clinical
examination, visual analog scale (VAS) score, a lower extremity functional scale (LEFS), and
lower extremity ultrasound for evaluation of gastrocnemius muscle size.
Inclusion Criteria:
- To participate in the intervention portion of the study, patients must have a
confirmed diagnosis of functional PAES.
- Patients must report ongoing leg pain during or after physical activity at the time of
intervention.
- Patients must have failed prior conservative treatment and have been experiencing
exertional leg pain for > 6 months.
- Patients must be between the age of 18 and 50.
Exclusion Criteria:
Any subject will be excluded from the study if he/she has any of the following:
- History of muscle/tendon ruptures to the lower extremities
- History of a neurological disease that would affect running or jogging
- History of adverse reactions to BTX-A
- Concomitant diagnosis of exertional compartment syndrome or other cause for leg pain.
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