Morton’s Neuroma, CRPS, and the role of Vitamin C and Mirror Therapy.
Complex Regional Pain Syndrome (CRPS, also known as RSD) is a rare, but not uncommon condition that can cause significant, sometimes life changing pain and loss of function in either, the lower leg and foot, or the lower arm and hand. It can also affect those that have had excision surgery for Moron’s neuroma.
CRPS is generally caused by trauma such as ankle or wrist fracture, or by a period of immobilisation such as having the foot or arm in a plaster cast or brace. Sometimes, even a seemingly very minor injury such as a sprained ankle can trigger CRPS.
Approximately 80% of people affected by CRPS are European, or have European ancestry. CRPS associated with trauma affects approximately 26 people per 100,000 every year (1). Much like Morton’s neuroma it affects 4 times more women than men, and like Morton’s neuroma the typical age of onset is mid-forties. The female bias however, could simply be explained by the fact that women suffer more fractures especially of the wrist than men, making them more likely to develop CRPS.
Most cases of CRPS are associated with fracture and the upper limb seems to be more commonly affected than the lower limb.
CRPS also occurs at a surprisingly high rate of just under 4.5% for those having elective or planned foot and ankle surgery (1), though some UK podiatric surgeons suggest that the risks of CRPS from Morton’s neuroma excision surgery alone is as low as 0.46% (2).
Excision of Morton’s neuroma is the biggest cause of surgically induced CRPS in the foot (3,4). The exact rate of CRPS is hard to know for sure, because estimates are based on retrospective studies that look back on patient’s treatment records, meaning they rely on clinicians being able to recognise and document or report a complex condition that can easily be mistaken for other conditions. The true rate of CRPS could be either higher or lower that the figures quoted (3).
What are the features of CRPS?
Constant or fluctuating pain is the most prominent feature of CRPS. The pain is often out of proportion to the injury or stimuli. CRPS can cause a variety of symptoms including, swelling, movement disorders such as tremor or involuntary muscle contraction, and pain is often felt from even the lightest touch or pressure.
Other features include altered skin temperature and altered nail and hair growth, and overall increased sensitivity to pain. Body perception disturbances are not uncommon, such as the hand or foot feeling like it doesn’t belong to the owner.
CRPS is hard to diagnose, for patients developing CRPS following Morton’s neuroma excision surgery, the average length of time from onset to diagnosis is just over 9 and a half months (3). In extreme cases the effects can drive sufferers to seek amputation of the affected limb, however around 16 % of those who proceed with amputation continue to experience the same level of pain.
The outlook for most is good, with many experiencing substantial improvement or remission of symptoms within 12 months, though for some, full recovery may never be attained or can take some years.
Studies have helped develop a profile of those most susceptible to developing CRPS. Just about 50% of CRPS sufferers have a previous history of anxiety and depression. CRPS sufferers are 3.5 times more likely to experience migraine especially migraine with aura than the general population. Smokers and those having repeat forefoot surgery also have increased risk.
The image below illustrates how the foot can look in the early stages of CRPS. The foot is often moderately swollen and slightly discoloured and warmer due to increased blood. In later stages the appearance can reverse, with the foot becoming cooler and darker and slightly bluish-purple discolouration.
What can be done to reduce the risk of developing CRPS in the first place?
Avoidance of trauma and surgery are the two obvious things that spring to mind. However, as we all know, avoidance of such things, especially slips and trips is easier said than done.
If you are unlucky enough to suffer a fracture or if you are waiting for elective foot and ankle surgery you should give serious consideration to taking Vitamin C.
The reason why is clearly illustrated by a 2007 study of men and women who had fractured their wrists. Following their fractures, 317 patients were given Vitamin C daily for 50 days, and 99 were given a placebo tablet.
Only 2.4% of the Vitamin C group went on to develop CRPS, compared with 10.1% of the control placebo group. This research has since been repeated many times nearly all studies showing Vitamin C can reduce (but not entirely prevent) rates of CRPS in those suffering fracture or undergoing elective surgery (5).
Treatment of CRPS
Like most things in medicine, better outcomes are achieved with early diagnosis and treatment. Treatment typically involves the use of differing drugs that include antidepressants, anticonvulsants and anti-bone loss drugs.
Other treatments includes repeat local anaesthetic injections, epidurals similar to those given during childbirth and spinal cord stimulators.
An emerging treatment that shows some promise that does not involve drugs involves the use of mirrors. The affected side is hidden and the other foot is then observed by the patient performing movement or activities that would normally be painful. Tricking the brain to process information differently does seem to significantly help reduce pain both during and after mirror therapy especially if performed regularly over a 3 month period (6).
Cryosurgery and CRPS.
Cryosurgery to sensory nerves (the nerves that contain Morton’s neuroma) triggers a localised breakdown of the nerve however the nerve is able to regenerate and return to normal function. Critically, Cryosurgery avoids cutting the nerve. Cryosurgery has been applied to nerves for pain relief since 1961 to approximately 30 nerves throughout the body (7). Thankfully, while CRPS does not seem to be a prominent risk for those having cryosurgery to a nerve or a neuroma, we would still advise anyone having any treatment for a neuroma, be it an injection of steroid, Cryosurgery or excision surgery to consider Vitamin C.
Most studies dealing with Vitamin C and CRPS suggest either taking either a full, or half a gram (1000mg / 500mg) of Vitamin C approximately 1 week before and up to 30-40 days post treatment. Always discuss with your doctor or clinician first.
CRPS charity: https://www.burningnightscrps.org
- De Mos M, De Bruijn AG, Huygen FJ, Dieleman JP, Stricker BH, Sturkenboom MC. The incidence ofcomplex regional pain syndrome: a population-based study. PAIN 2007;129:12–20.
- Tollafield D. Morton’s Neuroma Podiatrist turned patient: My own journey 2018 ISBN-13: 9781981779284 page 95.
- Incidence of Complex Regional Pain Syndrome after Foot and Ankle Surgery 2014
- Anderson DJ, Fallet LM. Regional pain syndrome of the lower extremity: a retrospective study of 33 patients. J Foot Ankle Surg 38:381–387, 1999.
- Zollinger PE, Tuinebreijer WE, Breederveld RS, Kreis RW. Can vitamin c prevent complex regional pain syndrome in patients with wrist fractures? A randomized, controlled, multicenter dose-response study. J Bone Joint Surg Am. 2007;89:1424-1431. Mirror therapy for Complex Regional Pain Syndrome (CRPS)-A literature review and an illustrative case report.
- Sayegh Scand J Pain.2013 Oct 1;4(4):200-207. doi: 10.1016/j.sjpain.2013.06.002.
- Trescot AM. Cryoanalgesia in interventional pain management. Pain Physician. 2003; 6(3):345–360
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