Saturday Night Palsy
Saturday night palsy refers to a compressive neuropathy of the radial nerve that occurs due to prolonged and direct pressure to the upper medial arm by an object or a surface . The radial nerve originates from the brachial plexus, carrying fibres from the C5-T1 ventral nerve roots. It innervates the medial and lateral heads of the triceps brachii muscle, as well as all twelve muscles in the posterior osteofascial compartments of the forearm. It provides motor innervation to the dorsal arm muscles and extrinsic extensors of the wrist and hand, as well as sensory innervation to most of the back of the hand (except the back of the 5th digit and adjacent half of 4th digit) .
Saturday night palsy is also known as the “honeymoon palsy”, which describes an event where an individual falls to sleep on their partner’s arm, compressing the person’s radial nerve for an extended period. Other terms for Saturday night palsy include “lover’s palsy”,” park bench palsy” and “crutch palsy”. Essentially, Saturday night palsy can be caused by any unnatural positioning or use of equipment that compresses the radial nerve, which is where the terms have originated from [1,3].
History and Physical Examination
As described in the case above, patients often report symptoms following excessive alcohol consumption and sleeping in an unnatural position. Otherwise, they may report other mechanisms in which their inner arm may have been compressed. Sometimes, symptoms do not present until several days after the nerve compression, making the diagnosis of this presentation difficult. Patients can also report other symptoms such as weakness, numbness, tingling and pain in the arm .
On physical exam, patients present with a characteristic wrist drop and inability to extend the wrist and fingers to the metacarpophalangeal joints’ level. Patients may also present with loss of triceps reflex, and sensory deficits involving the back of the hand [1,4].
Saturday night palsy is mainly a clinical diagnosis and does not require further investigative measures. However, some tools may help evaluate differential diagnoses and prognosis of the presenting condition. Electromyography and nerve conduction studies may localize the lesion and help differentiate between other neuropathies such as the brachial plexus or peripheral neuropathies. Ultrasound is a low-cost and low-risk method that can help visualize the nerve and identify areas of damage. MRI can assist in visualizing the finer details that may not be noticeable on ultrasound, as well as other presenting problems such as soft-tissue masses. The X-ray can guide in assessing for fractures and dislocations that may be causing the nerve compressions [1,5]. While none of these measures is necessary for diagnosing Saturday night palsy, it may be worthwhile to consider them for individual patients that require further investigations and where other diagnoses are being considered.
Treatment of Saturday night palsy is mainly through physical therapy, involving a dynamic splint that holds the arm in extension and allows for full passive range of motion during use. This can be complemented with the help of supportive care, including analgesics such as non-steroidal anti-inflammatory drugs (NSAIDs), resting the arm, corticosteroids use, and steroid injections . To prevent re-injury of the nerve, it is important to counsel the patient on not repeating the same mechanism that caused the initial neural compression. Patients should also be counseled on the importance of physical therapy and following up in case of delayed recovery, which may necessitate other considerations such as surgical interventions [1,2].
References and Further Reading
- Ansari FH, Juergens AL. Saturday Night Palsy. [Updated 2020 May 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557520/
- Bumbasirevic, M., Palibrk, T., Lesic, A., & Atkinson, H. D. (2016). Radial nerve palsy. EFORT open reviews, 1(8), 286-294.
- Latef, T. J., Bilal, M., Vetter, M., Iwanaga, J., Oskouian, R. J., & Tubbs, R. S. (2018). Injury of the radial nerve in the arm: A review. Cureus, 10(2).
- DeCastro A, Keefe P. Wrist Drop. [Updated 2020 Jul 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK532993/
- Agarwal, A., Chandra, A., Jaipal, U., & Saini, N. (2018). A panorama of radial nerve pathologies-an imaging diagnosis: a step ahead. Insights into imaging, 9(6), 1021-1034.