Credit carditis or fat wallet syndrome-A neglected yet, preventable public health problem

Dear Editor,

Modern men tend to love their wallets, which is kept usually in their back pocket, while women tend to love their purses, and they usually carry them by hand or hang them from their shoulders. The use of a wallet sometimes gives rise to wallet neuritis, a condition associated with compression of the sciatic nerve, which has been extensively documented in men.[1] In the literature, various terms such as hip pocket syndrome, wallet-neuropathy, wallet sciatica, walletosis, fat wallet neuritis, fat wallet syndrome [Figure 1], and credit carditis are commonly used to refer to this condition.[2]

Figure 1.

Fat wallet syndrome (P.C. Niwedita Jha, AIIMS, Deoghar)

Wallet neuritis, also known as fat wallet syndrome, is a condition where the sciatic nerve on the same side as an exogenous wallet beneath the piriformis muscle becomes compressed, resulting in symptoms resembling lumbar sciatica. The use of a bulky pocketbook can affect the posture of the pelvic and dorso-lumbar spine, exerting irregular pressure on the pelvic muscles, intervertebral discs, nerve roots, and nerves. Contrary to previous beliefs, wallet neuritis is not uncommon, and its prevalence among different populations and occupational groups is yet to be estimated. The correlation between wallet texture, weight, types of currencies, types of cards, and clinical manifestations of wallet neuritis is still unknown.[3,4]

Some publications have referred to fat wallet syndrome as a subtype of piriformis syndrome, even though it can occur independently. Prolonged seating on a large, fatty wallet can lead to low back pain and radiate lower extremity pain, often referred to as back pocket sciatica. The term “credit carditis” was introduced in a letter to the editor in 1966, but the popularization of the condition occurred through the Seinfeld television series in the 1990s.[5] Scientific literature, such as a study published in the Journal of the American Medical Association in 1978, has described instances of credit card wallet sciatica, indicating that even relatively small wallets can cause symptoms of wallet neuritis.[5]

The mechanism by which a wallet in the rear compartment exacerbates sciatica is not fully understood. However, it has been hypothesized that repetitive compression of the sciatic nerve beneath the wallet could be a contributing factor. Animal models have shown that compression of the sciatic nerve leads to the expression of Nav1.8 channels and the c-fos gene, which are associated with nerve sensitization. Human model testing is yet to confirm this hypothesis.[6]

There is a lack of original contributions on wallet sciatica, with only a few case reports and case series available.[7] The clinical entity has not been demonstrated in the Indian population or in numerous developed and developing countries. Long-term reclining on a large, fatty wallet can negatively impact men’s postural balance and stress the anatomy of the lower back.[8]

Both acute and chronic compressions have negative effects on the nerve’s blood supply and can lead to the formation of fibrous tissue around the nerve due to the proliferation of fibroblasts. Animal models have provided evidence of these effects, demonstrating tissue fibrosis and alterations in gene expression. Chronic compression specifically triggers the upregulation of the c-fos gene in spinal sensory afferent neurons, resulting in heightened neural sensitivity. Sensitized central afferent nociceptive fibers release neurotransmitters that activate pain pathways in the spinal cord, leading to hyperalgesia and central sensitization.[9]

Wallet neuritis has been observed in attorneys, laborers, and physicians. A study described sciatica symptoms in a laborer who got stuck on a toilet seat, providing evidence for wallet sciatic compressive neuropathy. Even sitting on a hard surface or carrying objects like a cell phone, golf ball, or handkerchief in the rear pocket can compress the sciatic nerve. The diagnosis of wallet neuritis can be challenging as it may be confused with other causes of low back pain. MRI of the lumbosacral spine typically shows no significant pathological alterations, while nerve conduction studies may reveal demyelination of the sciatic nerve. Ultrasonography can indicate associated muscle hypertrophy and spasms in the piriformis muscle due to overuse.[6] Long-term use of a hip pocket wallet can cause sciatica-like symptoms that are difficult to differentiate from spinal conditions.

Preventing fat wallet syndrome is straightforward by keeping the wallet in the front pocket. However, if someone is already experiencing symptoms, there are several recommended methods to alleviate and treat the condition. Noninvasive approaches include using anti-inflammatory medications, engaging in stretching exercises, and strengthening the muscles in the affected area. Shockwave therapy is suggested by experts to reduce stiffness, while conditioning the glute muscles through exercises like clamshells and fire hydrant workouts is beneficial. In more severe cases, surgical decompression of the muscle and nerve may be prescribed as a treatment option. The compressed and sensitized sciatic nerve produces clinical symptoms similar to sciatica, regardless of whether a wallet is filled with credit cards or not. The exact size of a wallet that causes sciatica and which wallets are more trustworthy remain unknown. Prospective multicenter studies involving consumers of rear-pocket wallets are needed to provide answers to these questions.

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