Reviewed: Hashempur MH, Ghasemi MS, Daneshfard B, et al. Efficacy of topical chamomile oil for mild and moderate carpal tunnel syndrome: A randomized double-blind placebo-controlled clinical trial. Complement Ther Clin Pract. February 2017;26:61-67.
Carpal tunnel syndrome (CTS) is characterized by tingling, numbness, and weakness in the hand. Treatments include surgery, splinting, nonsteroidal anti-inflammatory drugs, and corticosteroids. In traditional Persian medicine (TPM), chamomile (Matricaria chamomilla, syn. M. recutita, Asteraceae) is considered an analgesic agent. In particular, chamomile flower extract is used as a topical treatment for joint pain. The authors of this study have previously reported that a standardized formulation of chamomile oil has been found to be beneficial in severe CTS. The purpose of this randomized, double-blind, placebo-controlled study was to evaluate the preparation’s effects on symptoms of mild-to-moderate CTS.
Patients over the age of 18 who met electrodiagnostic criteria for mild-to-moderate CTS were recruited from outpatient clinics of Shahid Faghihi Hospital and Imam Reza Polyclinic in Shiraz, Iran, between August 2014 and February 2015. Electrodiagnosis is a diagnostic method in which the body’s natural electrical activity, or the body’s response to an external electrical stimulus, is measured. Mild-to-moderate CTS was defined using various electrodiagnostic criteria, including compound latency, which is the time between nerve stimulation of a muscle and its response.
Included patients had at least two of the following symptoms: numbness, paresthesia (burning or prickling sensation on the skin), nocturnal pain, tingling, and positive Phalen, Tinel, or compression tests (assessments used in the diagnosis of CTS). Exclusion criteria were as follows: severe CTS; previous wrist trauma, fracture, or surgical release of the median nerve; intracarpal injection within six months of the study; cervical radiculopathy (pain caused by damage to a nerve root in the cervical spine) detected by electromyography; recent use of analgesics or corticosteroids; hypersensitivity to the study treatments; inability to complete the data-gathering sheet; neuropathy; collagen vascular diseases; rheumatoid arthritis; hyperthyroidism; diabetes; renal failure; and alcoholism.
The treatment preparation was made by the researchers. Chamomile flowers were purchased from a traditional herbal shop in Shiraz, Iran. The flowers were obtained from the nearby city of Kazeroon and were morphologically authenticated. The preparation method was based on historical medical literature. Powdered chamomile flower was boiled in distilled water, then the plant residue was removed and the resulting liquid was combined with sesame (Sesamum indicum, Pedaliaceae) seed oil (Golkaran Co.; Mashhad Ardehal, Kashan, Iran) and boiled until the water was removed. The authors note that the preparation contained 1% chamomile essential oil. The essential oil was analyzed by gas chromatography-mass spectrometry and the main components were found to be bisabolone oxide A (62.4%), bisabolol oxides A and B (15.5 and 2.1%, respectively), and -caryophyllene (7.5%). The placebo was 10% (by volume) sesame oil in pharmaceutical paraffin with 0.1% hydrodistilled chamomile essential oil. The authors state that the rationale for including a small amount of chamomile in the placebo was to convey chamomile odor to help maintain blinding.
All patients were instructed to wear a wrist splint to immobilize the wrist at night. Every morning and evening, patients were instructed to place five drops of the treatment or placebo on the palmar area of the wrist for four weeks. They also were instructed not to massage the wrist. The primary outcome measure, which was assessed at the beginning and end of the study, was the Persian version of the Boston Carpal Tunnel Questionnaire, which assesses function and symptom severity.
Of 112 assessed patients, 86 were enrolled in the study, and 43 were randomly assigned to the treatment or placebo group. Because nine patients were lost to follow-up, 39 completed the study in the chamomile group and 38 in the placebo group.
The improvement from baseline was significantly greater in the chamomile group than in the placebo group for symptom severity (P = .017), functionality (P = .0001), and dynamometry (a measurement of muscle power), for which the mean score slightly worsened in the placebo group (P = .040). Compound latency of the median nerve significantly improved in the chamomile group compared with the placebo group (P = .035). There were no other significant changes in electrodynamic measurements. No patients reported any adverse effects.
The authors concluded that four weeks of traditional chamomile oil treatment can improve symptoms and function in patients with mild-to-moderate CTS. It should be noted that sesame oil has been shown to have antioxidant, anti-inflammatory, and anesthetic properties. Therefore, the benefits seen in this trial cannot be attributed to chamomile alone. The chamomile oil and sesame oil could be working additively or synergistically. Limitations of the study include the short study duration (given that CTS is a chronic condition) and relatively small sample size. Nonetheless, this study provides support for the benefits of this treatment in CTS.
—Heather S. Oliff, PhD