Patients may report various symptoms depending upon the location of the trauma. In general, numbness and a tingling sensation are present in virtually all cases, while specific signs may be observed during the physical examination, such as an inability to use certain muscles, or loss of sensory input. If fractures are the cause of nerve injury, patients usually feel excruciating pain and report trauma that may have caused the fracture.

In the case of axillary injury, the radial nerve is damaged at the very beginning, and numerous symptoms may be present. Since both sensory and motor signaling of the entire arm is impaired, symptoms may include loss of the ability to extend the forearm, hands and fingers, as well as the inability to perform forearm supination. Wrist drop is present as well, while the loss of sensation in the posterior part of the arm and forearm can be discovered. The radial nerve provides sensory branches to the dorsal parts of 3 and a half digits (excluding the little finger, which is supplied by the ulnar nerve), and loss of sensation int he fingers may be experienced as well.

As the level of the injury descends, the number of symptoms are reduced, as smaller muscles and sensory branches are affected. Injury at the level of humeral shaft, along with bone fracture gives similar symptoms, but the activity of triceps brachii muscle is preserved, as the innervation of this muscle is above the site of injury [10]. If the injury occurs below the elbow and in the forearm, inability to extend the fingers and wrist drop may be the only motor deficits.

A proper physical examination can locate the approximate site of injury, and together with data regarding the onset, severity, and duration of symptoms, appropriate diagnostic procedures can be performed.

• Weakness

  There is an obvious wrist drop, due to weakness of the radial extensors of the wrist, as well as inability to extend the metacarpophalangeal joints or elevate the thumb. [physioknowledgebd.blogspot.com]

  Muscle testing of a patient with radial nerve palsy can incorrectly suggest median and ulnar weakness because of a decreased ability to stabilize the thumb and wrist. [ncbi.nlm.nih.gov]

  Radial groove (High): Cause: Fracture shaft of humerus, Saturday night palsy, Injection, Callus, Torniquet Deficit: Brachioradialis weakness, Wrist drop, Finger drop, Thumb drop, Sensory loss 3. [epomedicine.com]

  […] and finger flexion = radial nerve lesion Weakness of finger extension and radial deviation of the wrist on extension = posterior interosseous nerve lesion Weakness of triceps, finger extensors and flexors = c7,8 lesion General weakness of upper limb [en.wikipedia.org]

• Falling

  Of the 15 patients, two were injured during simple falls, two during baseball pitching, one by a fall from a height, one during skiing, and one by direct machine impaction during work. [ncbi.nlm.nih.gov]

  More often, though, they are due to chronic compression in the axilla; this is seen in drink and drug addicts who fall into a stupor with the arm dangling over the back of a chair (‘Saturday night palsy’) or in thin elderly patients using crutches (‘crutch [physioknowledgebd.blogspot.com]

  (Etiology) The following are the causes for Radial Nerve Dysfunction: Fracture of the humerus (the upper arm bone) Prolonged constriction of the wrist such as from wearing a tight bracelet or watch strap Falling asleep with one's arm hanging over the [dovemed.com]

  This can also happen if you fall asleep in a way that puts pressure on the nerve, such as with your arm hanging over a chair. In most cases, no treatment is needed. You will slowly get more strength and feeling. This can take weeks or even months. [myhealth.alberta.ca]

• Disability

  What matters is the effect of the disabilities on you, not the names of the disabilities themselves. [forums.moneysavingexpert.com]

  This age related disability was significant (p=0.003). Transient palsy was observed in 3 patients (10%) and mild wound infection in 2 (6%), which was not associated with age or open fracture. [ncbi.nlm.nih.gov]

  If recovery does not occur, the disability can be largely overcome by tendon transfers: pronator teres to the short radial extensor of the wrist, flexor carpi radialis to the long finger extensors and Palmaris longus to the long thumb abductor. [physioknowledgebd.blogspot.com]

• Swelling

  Corticosteroids injections into the area may reduce swelling and pressure on the nerve. Surgery to repair the nerve may be needed for chronic symptoms that don't respond to simpler treatments. [fairview.org]

  When muscle fibers tear, the capillaries that serve the muscle with blood also rupture, flooding the area with blood and other fluid, which in turn causes localized swelling. Ice reduces swelling and constricts blood flow in the broken capillaries. [livestrong.com]

  You may also have long-term swelling, burning, and changes to the color of the skin on your injured arm. Without treatment, you may lose all movement and feeling in your arm or hand. You may have long-term pain. [drugs.com]

• Soft Tissue Mass

  Magnetic resonance imaging of the right arm did not show any abnormal soft tissue mass, with a normal appearance of the humeral cortex and marrow signal. As no recovery was noted after four months, exploration of the right radial nerve was planned. [bjsm.bmj.com]

  Causes include fracture of the radius, elbow deformity, soft-tissue masses and compression by the extensor carpi radialis brevis. [patient.info]

  Wrist -causes could be due to elbow deformity and soft-tissue masses Axilla - here the most common cause is compression.However a dislocation of the head of the bone ( humerus ) is a possible factor as well.Additionally it could also be due to brachial [en.wikipedia.org]

• Diarrhea

  If the nerves serving the organs are involved, diarrhea or constipation may result, as well as loss of bowel or bladder control. Sexual dysfunction and abnormally low blood pressure also can occur. [webmd.com]

• Fracture

  BACKGROUND: Radial nerve palsy associated with humeral shaft fractures is the most common nerve lesion complicating fractures of long bones. [ncbi.nlm.nih.gov]

• Contusion

  Of the 10 PreR patients, 6 had nerve contusion and 2-nerve entrapment. Of the 3 PreNR patients, 2 had gross nerve damage and 1 nerve contusion and a history of spinal muscular atrophy. [ncbi.nlm.nih.gov]

  Many researchers also have emphasized that, in many cases, the radial nerve palsy caused by a shaft fracture is a contusion and, therefore, exploration of the nerve is unnecessary8, 28. [internalmedicine.imedpub.com]

  […] fractures humerus with radial nerve palsy was, exploration of the radial nerve with open reduction internal fixation for all the cases or external fixation for the open fractures cases but we found in all our explorations that there were only nerve contusions [omicsonline.org]

  In 44% (4 out of 9) with primary radial nerve palsy and the initial exploration, minor nerve injuries such as contusions or superficial damage were found. [link.springer.com]

• Muscular Atrophy

  Advocates for early exploration believe that late exploration can result in increased muscular atrophy, motor endplate loss, compromised nerve recovery upon delayed repair, and significant interval loss of patient function and livelihood. [ncbi.nlm.nih.gov]

• Joint Dislocation

  Other injuries: Broken bones, joint dislocations, significant bruises and injuries requiring the use of crutches can increase a person’s risk for radial nerve palsy. [baptisthealth.com]

• Suggestibility

  Furthermore, three infants had fat necrosis of the upper arm above the elbow, suggestive of compression of the radial nerve in the region of the spiral groove. Significant recovery of function was evident within 1 month in all four infants. [ncbi.nlm.nih.gov]

• Peripheral Neuropathy

  A patient with diabetic peripheral neuropathy experienced the acute onset of a proximal radial nerve palsy after prolonged use of a walker. [ncbi.nlm.nih.gov]

  Types of Peripheral Neuropathy There are several different kinds of peripheral neuropathies that stem from a variety of causes. [webmd.com]

  Medications associated with a risk of peripheral neuropathy include the cancer drugs cisplatin (Platinol) and vincristine; the HIV/AIDS medications didanosine (Videx), ritonavir (Norvir), stavudine (Zerit) and zidovudine (Retrovir); the antibiotics isoniazid [livestrong.com]

  Traumatic Peripheral Nerve Injury. Who, where, how? Approximately 20 million people in the United States have some form of peripheral neuropathy. There are more than 100 kinds of peripheral nerve disorders that can affect one nerve or many nerves. [saebo.com]

  Campbell WW (ed) (2005) Peripheral Neuroanatomy and Focal Neuropathies. In: Campbell WW (ed) DeJong’s The Neurologic Examination. 6th edition. Harper and Row Publisher Inc, pp 548–564 Google Scholar 12. [link.springer.com]

• Irritability

  In patients with de Quervain tenosynovitis, secondary irritation of the RSN is frequent. Other common causes include postoperative injury, external compression, and trauma. [emedicine.medscape.com]

  The lateral head of the triceps was extremely irritable to the point of spontaneously twitching after the decompression was performed. [bjsm.bmj.com]

  Fecal transplant is used to treat gut infections and is now being studied as a treatment for obesity, urinary tract infections, irritable bowel syndrome and more. [nytimes.com]

• Burning Sensation

  […] back at the wrist, or holding the hand Pain, numbness, decreased sensation, tingling, or burning sensation in the areas controlled by the nerve The health care provider will examine you and ask about your symptoms and medical history. [medlineplus.gov]

  […] the hand back at the wrist, or holding the hand Pain, numbness, decreased sensation, tingling, or burning sensation in the areas controlled by the nerve Exams and Tests The health care provider will examine you and ask about your symptoms and medical [pennstatehershey.adam.com]

  Continued The most common symptoms of polyneuropathy are: Tingling Numbness Loss of sensation in the arms and legs A burning sensation in the feet or hands Because people with chronic polyneuropathy often lose their ability to sense temperature and pain [webmd.com]

  Common signs and symptoms of Radial Nerve Dysfunction include: Abnormal sensations such as numbness, tingling, or burning sensation Sharp pain over the hand or forearm, thumb side (radial surface) of the hand, or the fingers nearest to the thumb (first [dovemed.com]

• Paresthesia

  When injured, radial neuropathies are therefore characterized by sensory symptoms of pain, paresthesia, and numbness, as well as motor symptoms of weakness of extension at the elbow, wrist (“ wrist drop ”), and/or fingers. [amboss.com]

  Retrieved 16 August 2016. ^ "Paresthesia Information Page: National Institute of Neurological Disorders and Stroke (NINDS)". www.ninds.nih.gov. Archived from the original on 2 December 2016. [en.wikipedia.org]

  In three-month follow-up her shoulder was better but still had paresthesia in SRN distribution. [casesjournal.biomedcentral.com]

  Wartenberg’s syndrome • Aka: Cheiralgia paresthetica • D/t compression of Superficial radial nerve as it emerges b/w ECRL and BR, 8 cm proximal to radial styloid 34. isolated pain or paresthesias over the dorsoradial aspect of the hand preceding history [slideshare.net]

• Stupor

  More often, though, they are due to chronic compression in the axilla; this is seen in drink and drug addicts who fall into a stupor with the arm dangling over the back of a chair (‘Saturday night palsy’) or in thin elderly patients using crutches (‘crutch [physioknowledgebd.blogspot.com]

  Saturday night syndrome (so named because it can be acquired by sleeping with the arm over the back of a chair whilst in a drunken stupor, so compressing the plexus): Is due to compression of the lower part of the brachial plexus. [patient.info]

The diagnostic workup of patients with suspected radial nerve palsy includes various imaging studies, and in some cases, EMG. Plain radiography should be initially performed in all patients. Regardless of the level of injury, X-ray of the entire arm should be performed and exclude fractures of the humerus, elbow, and radius, but tumors may also be a cause of nerve compression. If radiography shows inconclusive results, MRI can obtain a good view into soft tissues of the arm. Ultrasound is a cheap, easy, and minimally invasive study that can show nerve injury with very good efficacy, and is sometimes preferred over EMG [11] [12]. EMG studies are performed if MRI or ultrasound cannot determine the underlying cause. Through electric stimulation of various muscles, nerve conduction signaling, nerve injury can be easily identified, and the exact location can be established. Moreover, EMG can evaluate quantitative nerve damage, which has important implications in choosing optimal therapy. These studies serve not only for diagnosis but for follow-up of patients as well, to monitor the process of recovery.

Diffusion tensor imaging (DTI) is increasingly being used in clinical practice, and it is used for detecting very small neuropathological conditions, one of them being radial nerve palsy. Some studies have indicated that this imaging technique is good in detecting nerve injury in the case of acute compression [13] and that it should be used in patients with suspected radial palsy.

Once the diagnosis and the injury are assessed, appropriate therapeutic strategies can be implemented.

Depending on the magnitude of nerve damage and the underlying cause, treatment principles vary significantly.

In the case of low-grade trauma and mild injury to the nerve, only observation is recommended. It is established that complete spontaneous recovery occurs in patients with closed fractures of the humerus and that surgical treatment should not be indicated under these circumstances [14]. On the other hand, patients in whom functional deficits persists, which significantly impairs their daily activities, other modalities need to be used. Splinting of the affected arm is recommended as an initial method, to reduce the risk of further aggravation [15]. Surgical treatment is reserved for patients in whom no progress has been made after a prolonged period of time. Tendon transfer is one of the methods used in the attempt to restore normal function with promising results [16]. Nerve transfer has been conducted in severe injuries and has shown good results in long-term follow-up [17].

Rehabilitation therapy is an important part of recovery for the vast majority of patients, and aids in restoring normal function of the affected muscles. Rehabilitation is often carried out for a prolonged period of time (> 6 months, or more), with the idea of complete restoration of function, or in severe cases, as much as possible.

The prognosis of patients with radial nerve palsy almost strictly depends on the severity of injury [8]. For patients in which transient symptoms appear, without sensory or motor dysfunction (termed neurapraxia) [9], recovery is complete without any forms of therapy. More severe injuries, in which motor or sensory paralysis occurs (or both) require significant care, through various treatment forms. Surgical treatment is not indicated in all cases but is often necessary for patients who have persistent symptoms for a prolonged period of time without signs of recovery.

There are several potential causes of radial nerve palsy, but trauma is by far the most common cause. Fracture of the middle third of the humerus - the humeral shaft is the most common cause, while fractures of the elbow and ulna are also reported as causes of radial nerve injury. Surgical instrumentation has also been established as a possible cause [2], while severe muscular effort has also been noted [3]. Pressure from external sources can also cause radial nerve compression, which is seen in intoxicated patients (also known as "Saturday night palsy"). Congenital radial nerve injury is rare, but cases that are reported occur due to amniotic banding (limb entrapment in amniotic bands) and abnormal uterine activity [4].

Patients of any age and gender may be affected by this condition. Radial nerve injury is estimated to occur in approximately 11-12% of patients that suffer a fracture of the humeral shaft, more commonly in the middle and distal thirds area, and specific types of fractures (transverse and spiral) are associated with an increased risk for nerve damage [5].

The radial nerve originates from the posterior division of the brachial plexus. It descends along the arm and forearm and provides both sensory and motor innervation. This nerve is responsible for the majority of sensory signaling from the posterior aspect of the entire arm and supplies several muscles with motor fibers, including triceps brachii, brachioradialis, supinator, and to all extensors of the hand [6].

As the nerve descends from the brachial plexus through the arm, forearm and eventually reaching the hand, there are several points at which it is susceptible to injury. Firstly, this can occur in the axillary region, as a result of mechanical pressure, which can be seen in patients who are in deep sleep or intoxication. When the radial nerve descends along the radial groove, it can be damaged or compressed in the setting of humeral fractures. In fact, this is the most common site of radial nerve damage. Once the nerve passes through the spiral groove, it divides into two terminal branches - superficial sensory branch, and deep motor branch which passes through the fascia of the supinator muscle, to innervate these muscles and extensors of the hand. The nerve is susceptible to injury while passing through the supinator muscle, but fractures of the radius and elbow, as well as dislocation of the elbow [7], may result in radial palsy at this part of the arm. It is important to clarify that palsy can occur at any part of the radial nerve.

Because the principal cause of radial nerve palsy is trauma, and injury is often unexpected, prevention measures are not possible. However, an early diagnosis may prevent patients from further aggravating nerve injury, which can significantly prolong the process of recovery.

Radial nerve palsy is characterized by injury or compression of the radial nerve at various sites in the arm. The radial nerve originates from the brachial plexus and contributes numerous branches to the arm and forearm, providing both sensory and motor signaling. The most common cause of this condition is a fracture of the humerus because the nerve travels along the arm through the radial groove, the small depression in the humeral shaft [1]. Other causes may include fractures at other sites in the arm as a result of trauma, surgical instrumentation, and in rare cases, congenital radial nerve palsy may occur. Approximately 12% of patients who experience humeral fractures will develop radial nerve palsy, and clinical presentation depends on the site of injury. Failure to extend the forearm (as a result of triceps brachii inactivity), hand and fingers, wrist drop, decreased sensation, as well as numbness and a tingling sensation are all symptoms that may be observed. Since trauma is the cause in the majority of patients, severe pain and edema of local tissue may be present. Because symptoms depend on the location of the injury, a proper physical examination can help in diagnosis. The diagnostic workup is aimed at identifying the underlying cause, but also to evaluate the severity of the injury. Plain radiography, magnetic resonance imaging (MRI), ultrasound, and electromyography (EMG) are all used in evaluating patients with radial nerve palsy. Therapy depends on the scope of nerve damage, and the majority of patients with mild symptoms may spontaneously recover, with minimal or no sequelae, while surgical treatment may be necessary for patients with severe functional impairment. Rehabilitation is indicated for all patients, to facilitate recovery and restoration of normal muscular function. In severe cases, tendon or nerve transfer may be performed.

Radial nerve palsy is a term that describes an injury to the radial nerve, which is one of the main nerves of the arm and hand. This nerve supplies various muscles of the arm, such as triceps, and almost all finger muscles that perform the function of extension, and it also provides sensory signaling to the back of the arm and fingers. Radial nerve travels from the shoulder and terminates in the forearm, where it branches into two nerves. This disorder is most commonly caused by trauma and fracture of the bone of the upper arm. However, injury to the nerve may occur at various sites in the arm, which is why patients present with different symptoms. Usually, inability to extend the elbow, hand or fingers is observed, while numbness and a tingling sensation is frequently reported. Since trauma is often the cause, severe pain at the site of impact is reported, which can be accompanied by redness of the skin and swelling. The physician can identify the site of injury during the physical examination, after which the diagnosis can be confirmed by various studies. X-rays, ultrasound, magnetic resonance imaging and electromyography can be performed to assess the exact location and severity of nerve injury. Treatment, as well as prognosis, depend on the severity and location of the injury. Since nerve tissues heal very slowly, recovery may take up to several months. For patients with mild injury, observation with rehabilitation may be sufficient for full recovery, but for patients with significant functional impairment, surgery may be necessary.

1. Lowe JB, Tung TR, Mackinnon SE. New surgical option for radial nerve paralysis. Plast Reconstr Surg. 2002;110(3):836–43.
2. Wang JP, Shen WJ, Chen WM, Huang CK, Shen YS, Chen TH. Iatrogenic radial nerve palsy after operative management of humeral shaft fractures. J Trauma. 2009;66(3):800–3.
3. Streib E. Upper arm radial nerve palsy after muscular effort: report of three cases. Neurology. 1992;42(8):1632–4.
4. Richardson GA, Humphrey MS. Congenital compression of the radial nerve. J Hand Surg Am. 1989;14(5):901–3.
5. Shao YC, Harwood P, Grotz MR, Limb D, Giannoudis PV. Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br. 2005;87(12):1647-52.
6. Tuncel U, Turan A, Kostakoglu N. Acute closed radial nerve injury. Asian Journal of Neurosurgery. 2011;6(2):106-109.
7. Matsubara Y, Miyasaka Y, Nobuta S, Hasegawa K. Radial nerve palsy at the elbow. Ups J Med Sci. 2006; 111(3):315-20.
8. Venouziou AI, Dailiana ZH, Varitimidis SE, et al. Radial nerve palsy associated with humeral shaft fracture. Is the energy of trauma a prognostic factor? Injury. 2011;42(11):1289–93.
9. Seddon HJ. Surgical Disorders of the Peripheral Nerves. 1972:66-88
10. Ekholm R, Ponzer S, Törnkvist H, Adami J, Tidermark J. Primary radial nerve palsy in patients with acute humeral shaft fractures. J Orthop Trauma. 2008;22(6):408-14.
11. Toros T, Karabay N, Ozaksar K, Sugun TS, Kayalar M, Bal E. Evaluation of peripheral nerves of the upper limb with ultrasonography: a comparison of ultrasonographic examination and the intra-operative findings. J Bone Joint Surg Br. 2009;91(6):762-5.
12. Lo YL, Fook-Chong S, Leoh TH, et al. Rapid ultrasonographic diagnosis of radial entrapment neuropathy at the spiral groove. J Neurol Sci. 2008;271(1-2):75-9.
13. Jengojan S, Kovar F, Breitenseher J, Weber M, Prayer D, Kasprian G. Acute radial nerve entrapment at the spiral groove: detection by DTI-based neurography. Eur Radiol. 2015;25 (6):1678-83.
14. Szekeres M. Tenodesis extension splinting for radial nerve palsy. Tech Hand Up Extrem Surg. 2006;10(3):162-5.
15. Gousheh J, Arasteh E. Transfer of a single flexor carpi ulnaris tendon for treatment of radial nerve palsy. J Hand Surg [Br]. 2006;31(5):542-6.
16. Jacobson JA, Fessell DP, Lobo Lda G, Yang LJ. Entrapment neuropathies I: upper limb (carpal tunnel excluded). Semin Musculoskelet Radiol. 2010;14(5):473-86.
17. Mackinnon SE, Roque B, Tung TH. Median to radial nerve transfer for treatment of radial nerve palsy. Case report. J Neurosurg. 2007;107(3):666-71.