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Radial Nerve Palsy

Radial nerve palsy implies compression or injury of the radial nerve, which can occur anywhere from its origin at the brachial plexus to its terminal branches of the forearm and hand. Most commonly, injury occurs due to humeral shaft fracture, and clinical findings and symptoms depend on the localization. A proper clinical examination can identify the lesion, and treatment depends on the severity of the injury.


Presentation

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.

Respiratory Distress
  • Surgical exploration of the nerve was delayed because of respiratory distress. Six weeks later, when exploration was scheduled to be undertaken, some recovery was noted, and exploration was thus deferred.[ncbi.nlm.nih.gov]
Subcutaneous Nodule
  • Seventeen infants (68.0%) had a subcutaneous nodule representing fat necrosis in the inferior posterolateral portion of the affected arm.[ncbi.nlm.nih.gov]

Workup

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.

Treatment

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.

Prognosis

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.

Etiology

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].

Epidemiology

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].

Sex distribution
Age distribution

Pathophysiology

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.

Prevention

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.

Summary

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.

Patient Information

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.

References

Article

  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.

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Last updated: 2018-06-22 05:29