An Unusual Case of Foot Drop

Recently one of my neighbors developed foot drop; I saw her using a walker and she couldn’t walk her dog without someone with her. Of course, I volunteered. I couldn’t help asking her what happened.

She explained the foot drop came on suddenly. Her doctor told her it was slimmer’s palsy. (I’m thinking, what’s that?) She said he told her it probably would resolve on its own and if not, she might need surgery. She asked if chiropractic might help. Of course, I said yes, but I must admit I was a bit peeved with myself because I had not heard of this term.

There are many causes for foot drop; I’ve personally treated patients with foot drop with positive results, but not a patient with a diagnosis of slimmer’s palsy. So, I did some research on this term and now I am sharing it with you.

Slimmer’s Palsy

Slimmer’s palsy is a term used when there is entrapment of the common peroneal nerve at the neck of the fibula and is associated with rapid weight loss. It can be exacerbated by leg crossing or prolonged squatting. Carpet layers, plumbers and farmworkers are also at risk for common peroneal nerve entrapment. Most improve when they stop the activity. Frequent breaks and knee pads can help.

Even when the nerve lesion is clearly at the fibular neck, there are a variety of causes that may not be immediately obvious.^1-2 I was not aware of weight loss being associated with peroneal nerve entrapment. This is a diagnosis of elimination along with the associated history.

Symptoms & Diagnosis

Foot drop symptoms require a meticulous neurological evaluation to ascertain the site of the lesion. There are many causes of acute-onset foot drop, ranging from deep fibular nerve or sciatic nerve injury caused by trauma or a compressive mass such as a neuroma, to spinal cord disorders like disc herniation causing L4-5 radiculopathy. Even brain disorders like MS, stroke or ALS can result in foot drop, including various muscular dystrophies affecting the tibialis anterior muscle.

Foot drop causes significant disability and markedly restricts everyday activities, which is distressing because it can cause falls, resulting in other injuries.

Nerve conduction and electromyographic studies are useful adjuncts in localizing the site of injury, establishing the degree of damage, and predicting the degree of recovery. ³ Imaging, MR or ultrasonography, is important in establishing the cause of foot drop, be it at the level of the spine, along the course of the sciatic nerve or in the popliteal fossa.^4-5

It is not always easy to clearly determine the cause. The main challenge is to differentiate between radiculopathy and peripheral nerve injury or a neurological systemic disease.

Treatment

Chiropractic practitioners are underutilized in the conservative management of this disorder. Unfortunately, there is still controversy over treatment and little data available on the conservative management of this problem, so it is often not being addressed appropriately.⁷

“There are a range of treatment options, some are causal and others symptomatic in nature. Typically, these treatments cannot be provided by one specialty alone.” – Anne Elisabeth Carolus⁸

I found only one ongoing clinical trial on the efficacy of conservative vs surgical treatment to determine which patients with foot drop caused by peroneal nerve root entrapment need operative intervention or conservative management (ClinicalTrials.gov: NCT04695834). The trial will not be completed until 2027.

So, what was causing of my neighbor’s foot drop? No diagnostic studies had been performed to confirm there wasn’t any other condition causing this acute onset. The only recommendation was to stop crossing her legs and use the walker until it resolved.

She did receive a referral for physical therapy, but no appointments were available for over two months, at least under her insurance plan (thanks to our crazy health care system).

The Cause?

Initially, she didn’t mention that she had lost 25 lbs. over a two-month period by taking Ozempic. (I think she was a little embarrassed.) As with many patients, history is key. With that information, I understand how she got that diagnosis; but without some sort of diagnostic testing, how could one be certain?

Ozempic is prescribed for diabetics. However, semaglutide, the active ingredient in Ozempic and Wegozy, are not only prescribed for overweight diabetics. It has become popular with patients who want to lose weight quickly.

My neighbor wanted to lose weight quickly for a family wedding. I didn’t think she was that “overweight”; maybe 10 or 15 pounds. Who knew she might develop foot drop? She ended up going to the event with her walker, but in the pictures she looked slimmer. (A win/lose situation?)

I reviewed all the side effects reported by the pharmaceutical companies that make Ozempic and Wegozy.⁹ Foot drop / slimmer’s palsy is not mentioned. Apparently, this problem can happen with any dramatic weight loss over a short period of time. It is not associated directly with semaglutide.

The present theory is that rapid weight loss leads to the depletion of adipose tissue. When the peroneal nerve is not protected by the normal fat pad as it courses adjacent to the fibular head on the medial side, and by the peroneus longus tendon on the lateral side, entrapment can occur. It can be aggravated mechanically by long periods of crossing the legs and/or squatting.^10-11

Regarding my neighbor, she was able to receive treatment from a team of practitioners at a multidisciplinary sports medicine clinic. She received intense physical therapy from a team chiropractor with a specialty in sports injuries (DACBSP) and one minor intervention of hydrodissection from a sports team physician.^12-13 (Just south of San Diego, there is an Olympic training center in Chula Vista; hence a plethora of sports and musculoskeletal specialists.)

This patient was practical, lucky and had resources; she didn’t wait around to get her PT appointment, which her insurance would cover. Timely care is important, especially with nerve regeneration, which might not have been possible without surgical intervention. Patients need to be involved in their own care, especially now with all the problems with our health care system.

Chiropractic Relevance

We chiropractors need to keep in mind that the cause of foot drop could be rapid weight loss. We need to ask the right questions; especially when the weight loss exceeds 5 kg a month and is prolonged over several months. Further care should be taken if the patient has known conditions predisposing them to neurological issues.^14-16

Given the growing popularity of weight-reducing medications, I would anticipate this not-so-common disorder will increase in prevalence in the near future. Chiropractors can certainly manage slimmer’s palsy with conservative treatment, which should be the first option.

References

1. Koller RL, et al. Strawberry pickers’ palsy. Arch Neurol, 1980;37(5):320.
2. Kodaira M, et al. Squatting-induced bilateral peroneal nerve palsy in a sewer pipe worker. Occup Med, 2017 Jan;67(1):75-77.
3. Thatte H, et al. Electrodiagnostic Evaluation of Peroneal Neuropathy. Treasure Island, FL: StatPearls Publishing, 2023.
4. Bayrak IK, et al. Diagnostic value of ultrasonography in peroneal neuropathy,” Turkish J Med Sci, 2018;48(6):Article 6.
5. Nageeb RS, et al. Role of superficial peroneal sensory potential and high-resolution ultrasonography in confirmation of common peroneal mononeuropathy at the fibular neck, [url=https://rdcu.be/dhreG]https://rdcu.be/dhreG[/url]
6. Van den Bergh FRA, et al. Peroneal nerve: normal anatomy and pathologic findings on routine MRI of the knee. Insights Imaging, 2013;4:287-299.
7. Oosterbos C, et al. Controversies in treatment strategies in patients with foot drop due to peroneal nerve entrapment: results of a survey among specialists. Brain Spine, 2022 Apr 9;2:100887.
8. Carolus AE, et al. The interdisciplinary management of foot drop. Dtsch Arztebl Int, 2019 May 17;116(20):347-354.
9. McCrimmon KK. “Wegovy vs. Ozempic: The Truth About New ‘Weight-Loss’ Drugs.” UCHealth Today, April 5, 2023.
10. Meylaerts L, et al. Peroneal neuropathy after weight loss: a high-resolution ultrasonographic characterization of the common peroneal nerve. Skeletal Radiol, 2011 Dec;40(12):1557-62.
11. Öztürk I, et al. Neuropathic pain in peroneal nerve entrapment at the fibular head. Arq Neuropsiquiatr, 2022 Nov;80(11):1134-1140.
12. Song B, et al. Hydrodissection as a therapeutic and diagnostic modality in treating peroneal nerve compression. Proc Bayl Univ Med Cent, 2020 May 5;33(3):465-466.
13. Fortier LM, et al. An update on peroneal nerve entrapment and neuropathy. Orthop Rev, 2021 Jun 19;13(2):24937.
14. Sotaniemi KA. Slimmer’s paralysis peroneal neuropathy during weight reduction. J Neurol Neurosurg Psychiatry, 1984 May;47(5):564-566.
15. Shields LBE, et al. Varied presentation and importance of MR neurography of the common fibular nerve in slimmer’s paralysis. Case Rep Neurol, 2021 Aug 19;13(2):555-564.
16. Oh MW, et al. Bilateral common peroneal neuropathy due to rapid and marked weight loss after biliary surgery: a case report. World J Clin Cases, 2021 Mar 16;9(8):1909-1915.