Pronator teres is a muscle situated in the palm-side of the forearm. This muscle originates from two locations – one from your Ulna (medial forearm bone) and one from the end region of the Humerus (upper arm bone) at the elbow joint. The Pronator teres attaches to the other forearm bone (Radius) and contraction of the muscle causes pronation (rolling the forearm and wrist inwards so the palm faces down). It also plays a supportive role in elbow flexion. Pronator teres syndrome (PTS) refers to a condition in which the median nerve is compressed between the 2 heads of pronator teres leading to a compressive neuropathy. The median nerve is a branch of the brachial plexus in the neck which supplies the thumb, index, middle and inside portion of the ring finger. PTS may be overlook as the median nerve is more commonly subjected to compression at the wrist which relates to carpal tunnel syndrome (Asheghan et al., 2016).
Characteristic features include tingling and numbness of the thumb and two adjacent fingers (palmar side of the hand) along with the weakness of the muscles that innervated by median nerve’s branches (Flexor Digitorum Profundus, Pronator Quadratus and Flexor Pollicis Longus).
PTS typically arises from repeated gripping and forearm pronation actions (e.g. hammering, heavy lifting, tennis) leading to the Pronator teres growing larger, subsequently compressing the median nerve (Dididze, 2019).
It will be tender when the muscle is palpated and this may also recreate the symptoms in your hand and forearm. Resisting pronation – the movement it is responsible for, may also bring on the associated symptoms (Hartz et al., 1981). Your Physiotherapist will take a detailed history of your symptoms and conduct a series of physical tests which will help them to rule in/out the presence of PTS.
They may also recommend a nerve conduction study which will determine if there is a reduction in the speed in which electrical signals are transmitted through the median nerve. Compression neuropathies like PTS typically presents with a decreased conduction velocity compared to the unaffected side.
Providing a timely and accurate diagnosis will ensure the most effective and suitable treatment plan can be devised and put in to action straight away. Your Physio will want to understand how your symptoms are affecting your life so they can help you create goals geared towards achieving recovery. Progress towards your goals will be measured through regular re-assessment which will also allow for adjustments in your treatment to be made.
Initial management comprises of reducing inflammation by avoiding or modifying activities that increase symptoms, relative rest, and anti-inflammatory medications (NSAIDs) (Carter & Weiss, 2015). In most cases, patients with PTS stay relatively functional and can continue working with some limitations or adjustments and conservative treatment should be trialed for at least 6 weeks.
Your Physiotherapist can help with specific stretching and strengthening exercises to help you improve the symptoms. Treatment may include manual therapy techniques (trigger point therapy and deep tissue massage), offer advice regarding temporary offloading of the muscles and methods to specifically target the region to build strength and resilience, ultimately to restore normal physiology and mitigate compression on the median nerve.
Should conservative management be unsuccessful, local corticosteroid injection should be considered as an adjunct to supporting the rehabilitation progress. In the absence of positive results from steroid injection, the remaining option is a referral to a specialist Orthopaedic surgeon for decompression or release. This procedure is usually performed endoscopically and has demonstrated favourable outcomes (Hsiao, Shih & Hung, 2017).
Asheghan, M., Hollisaz, M. T., Aghdam, A. S., & Khatibiaghda, A. (2016). The prevalence of pronator teres among patients with carpal tunnel syndrome: Cross-sectional study. International journal of biomedical science: IJBS, 12(3), 89.
Carter, G. T., & Weiss, M. D. (2015). Diagnosis and treatment of work-related proximal median and radial nerve entrapment. Physical Medicine and Rehabilitation Clinics, 26(3), 539-549.
Dididze, M. (2019). Pronator Teres Syndrome. In StatPearls [Internet]. StatPearls Publishing. [Accessed 21/5/2020].
Hartz, C. R., Linscheid, R. L., Gramse, R. R., & Daube, J. R. (1981). The pronator teres syndrome: compressive neuropathy of the median nerve. J Bone Joint Surg Am, 63(6), 885-90.
Hsiao, C. W., Shih, J. T., & Hung, S. T. (2017). Concurrent carpal tunnel syndrome and pronator syndrome: a retrospective study of 21 cases. Orthopaedics & Traumatology: Surgery & Research, 103(1), 101-103.