Entrapment neuropathy is a term describing a type of neuropathy that is rather commonly encountered in clinical practice (carpal tunnel syndrome is one of the examples) and results from either compression, traction or structural impairment of the nerve [1] [2] [3]. As the nerve becomes compressed or "entrapped" in tissues after trauma or some other form of injury, the blood supply to the nerve is diminished, eventually causing edema, ischemia, necrosis and death of neuronal tissue if the structural deformity is not repaired promptly [4] [5]. During this process, typical symptoms of neuronal injury arise, such as pain, paresthesia, and numbness [1]. Depending on the affected nerve, both sensory and motor deficits can be observed. For example, deltoid weakness indicates axillary nerve entrapment; restriction of wrist flexion is present in the setting of median nerve compression, whereas loss of sensation in the dorsal proximal areas of the index finger, middle finger and the thumb suggests radial nerve entrapment [1] [2]. It must be noted that several nerves could be entrapped at more than one anatomical location, which is why recognizing associated signs and symptoms is pivotal for identifying the affected nerve [1] [2] [6]. The appearance of symptoms can be abrupt or slowly progressive [1].

• Limb Pain

  Página 212 - Jensen TS, Krebs B, Nielsen J, Rasmussen P: Immediate and longterm phantom limb pain in amputees — incidence, clinical characteristics and relationship to pre-amputation limb pain. Pain 21:267278, 1985. ‎ [books.google.es]

• Painter

  painters, electricians, volleyball and tennis players), which may result in chronic mechanical stretching and irritation of the suprascapular nerve Rotator cuff injury (Vad et al., 19 using electrodiagnostic testing, studied patients with full-thickness [musculoskeletalkey.com]

• Paresthesia

  When evaluating patients with unilateral leg pain and paresthesias, one should consider the possibility of entrapment of peripheral nerve. Electrodiagnostic studies are helpful in establishing the diagnosis. [ncbi.nlm.nih.gov]

  Patients with carpal tunnel syndrome (CTS) or ulnar neuropathy in their dominant hand may complain of bothersome paresthesias which impair certain work activities requiring fine motor skills. [connect.springerpub.com]

• Foot Drop

  Foot drop is often caused by an entrapment below and behind the knee before the nerve splits into these two branches, but I knew this was not the cause. [tonymorris.github.io]

  Four patients had classical rheumatoid arthritis, while foot-drop developed in one man after trauma to the knee. In all five patients, a painful palpable enlargement in the popliteal area became most symptomatic with the [jamanetwork.com]

  Motor nerve injury would then cause two particular symptoms of weakness, foot drop and inversion sprain. Foot drop occurs when walking. The foot will slap on the ground when the heel strikes the surface. [neckandback.com]

  Weakness usually starts in a distribution of a single peripheral nerve with unilateral wrist drop, foot drop, or grip weakness. 1–3,15 It can differentially involve branches of a peripheral nerve; a common clinical finding noted in some patients is the [touchneurology.com]

  It needs to be distinguished from an L5 radiculopathy (foot drop) when tripping and fractures occur, especially in older people. [care.diabetesjournals.org]

• Gait Ataxia

  Gait ataxia, with difficulty walking or frequent falls, is observed. [spineuniverse.com]

A delayed diagnosis of entrapment neuropathy and nerve compression may lead to irreversible neuronal injury and cause a significant impairment in daily life, thus early recognition of this clinical entity is of absolute necessity [3] [6]. One of the first steps toward the diagnosis is a detailed patient history that will determine the duration of symptoms and their severity, followed by a thorough physical examination, perhaps the pivotal part of the diagnostic workup [1] [6]. Depending on the cause and location of symptoms, a complete motor evaluation of muscle groups and the sensorium in the areas where the patient reports pain, paresthesias, or numbness, is the mainstay in revealing which nerve is injured [1] [6]. A presumptive diagnosis might be made solely on clinical findings, but imaging and electrophysiologic studies are highly useful in confirming entrapment neuropathy. Plain radiography, although important in delineating skeletal injuries as potential causes, is of no use in assessing nervous tissues [1]. For this reason, ultrasonography (US) and magnetic resonance imaging (MRI) are recommended but are not equally effective for all anatomical sites [1] [2] [6] [7]. A hypoechogenic appearance of the nerve, as well as edema, thickening, and fatty atrophy of the muscles supplied by the injured nerve, are frequent findings on US, whereas swelling and hyperintensity are seen on MRI studies [1] [4] [7]. Conversely, electromyography (EMG) and nerve conduction studies are often used in the setting of peripheral nerve injury and provide important clues in discerning between peripheral and central nerve injuries [1] [6].

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3. Choi S-J, Ahn JH, Ryu DS, et al. Ultrasonography for nerve compression syndromes of the upper extremity. Ultrasonography. 2015;34(4):275-291.
4. Deniel A, Causeret A, Moser T, Rolland Y, Dréano T, Guillin R. Entrapment and traumatic neuropathies of the elbow and hand: An imaging approach. Diagn Interv Imaging. 2015;96(12):1261-1278.
5. Kobayashi S, Meir A, Baba H, Uchida K, Hayakawa K. Imaging of intraneural edema by using gadolinium-enhanced MR imaging: experimental compression injury. AJNR Am J Neuroradiol. 2005;26(4):973-980.
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7. Lawande AD, Warrier SS, Joshi MS. Role of ultrasound in evaluation of peripheral nerves. Indian J Radiol Imaging. 2014;24(3):254-258.