x
x

DOUBLE CRUSH SYNDROME

Introduction

Double crush syndrome (DCS) was first described in 1973 by Upton and McComas,1 who theorized that asymptomatic compression at one site of a peripheral nerve increased its susceptibility to impairment at another site. This “double crush” eventually leads to disruption of axonal transport along the nerve and increases the vulnerability of distal axons to compression syndromes.1,2 However, there is some controversy surrounding several aspects of DCS, including etiology, pathophysiology, diagnostic criteria, and nomenclature, as the condition can result from other pathologic processes and is not limited to two sites of a given nerve. Most cases of suspected DCS are managed conservatively at first; conservative and surgical interventions are usually based on the condition(s) and nerve involved.2-4

Pathophysiology

  • The etiology and pathophysiology of DCS is widely debated, and there are several unanswered questions regarding its underlying mechanisms2-4 One theory proposes that there is a disruption of nutrient flow in both anterograde and retrograde directions along the axons2
  • As a result, the nerve will gradually undergo morphological and functional changes, ultimately manifested by various DCS symptoms3
  • Some patients have a predispositon for entrapment neuropathies related to congenital narrowing of the nerve’s osseous tunnel or thickening of an overlying retinaculum (eg, inflammation, edema), which can result in nerve compression5
  • Other factors that can alter neural physiology and increase the risk for DCS include some pharmacotherapies, infectious disease, anatomic abnormalities, hypothyroidism, hereditary neuropathy, uremic neuropathy, vitamin deficiency, and chronic alcoholism2

Related Anatomy

  • Peripheral nerve axon
  • Osseous tunnel
  • Flexor retinaculum

Incidence and Related Conditions

  • As there are no standardized criteria for diagnosing DCS, epidemiologic data are lacking
  • The most widely studied association is that between carpal tunnel syndrome (CTS) and cervical radiculopathy (CR)
    • In studies focused on these conditions, incidence estimates of concomitant CTS and CR vary widely from <10% to >70%4,6
    • If strict anatomic and electrodiagnostic criteria are applied, DCS incidence estimates are low2
    • Related conditions include: CTS, thoracic outlet syndrome, CR, cubital tunnel syndrome, Guyon’s ulnar nerve entrapment, diabetes, and edema

Differential Diagnosis

  • Carpal tunnel syndrome
  • Thoracic outlet syndrome
  • Cervical radiculopathy
  • Cubital tunnel syndrome
  • Guyon’s ulnar nerve entrapment
ICD-10 Codes

  • DOUBLE CRUSH SYNDROME

    Diagnostic Guide Name

    DOUBLE CRUSH SYNDROME

    ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

    DIAGNOSISSINGLE CODE ONLYLEFTRIGHTBILATERAL (If Available)
    DOUBLE CRUSH SYNDROME (CERVICAL ROOT DISORDER)G54.2   

    ICD-10 Reference

    Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
  • The perikaryon (A) synthesizes neural components that are key to normal axon function. These components move by axoplasmic flow. Serial impairments to flow can cause neural dysfunction at point (B).
    The perikaryon (A) synthesizes neural components that are key to normal axon function. These components move by axoplasmic flow. Serial impairments to flow can cause neural dysfunction at point (B).
Basic Science Photos and Related Diagrams
Basic Science Pics
  • A – Normal perikaryon and axon with normal flow (large horizontal arrow), normal function and no symptoms (paresthesias). B. - Normal perikaryon and axon with slightly impaired flow (horizontal arrow), normal function and no symptoms (paresthesias). C. - Normal perikaryon and abnormal axon with moderately impaired flow (small thin arrow) at two levels (X&Y), with abnormal function and symptoms (Sx) representing classical Double Crush Syndrome. D. - Normal perikaryon and abnormal axon flow (small thin arrow)
    A – Normal perikaryon and axon with normal flow (large horizontal arrow), normal function and no symptoms (paresthesias). B. - Normal perikaryon and axon with slightly impaired flow (horizontal arrow), normal function and no symptoms (paresthesias). C. - Normal perikaryon and abnormal axon with moderately impaired flow (small thin arrow) at two levels (X&Y), with abnormal function and symptoms (Sx) representing classical Double Crush Syndrome. D. - Normal perikaryon and abnormal axon flow (small thin arrow)
Symptoms
Numbness
Painful paresthesias
Impaired pinch and/or grip
Nighttime paresthesias
Dropping objects more frequently than normal
Typical History

The typical patient with Double Crush Syndrome is a middle-aged female with slightly elevated A1C, history of chronic neck arthritis and severe bilateral paresthesias. The patient is complaining of numbness, pain, dropping objects frequently and nighttime paresthesias.  The symptoms have been occurring for six months.

Positive Tests, Exams or Signs
Work-up Options
Images (X-Ray, MRI, etc.)
  • Cervical Arthritis is a common proximal component in Double Crush Syndrome. See root impingement at the arrow.
    Cervical Arthritis is a common proximal component in Double Crush Syndrome. See root impingement at the arrow.
Treatment Options
Conservative
  • The majority of cases of suspected DCS are treated conservatively at first; multimodal therapy is often needed and the focus should be on managing the unique pathology and symptomatology of each lesion, with physicians addressing each suspected level of nerve compression or involvement2,4 
  • Cervical Radiculopathy
    • Orthosis or short-term immobilization with a soft collar
    • Activity modifications
    • Non-steroidal anti-inflammatory drugs (NSAIDs)
    • Corticosteroid injections
    • Oral steroids
    • Physical therapy
  • Thoracic outlet syndrome
    • Exercise
    • NSAIDs
    • Bracing
  • Carpal Tunnel Syndrome
    • Bracing
    • NSAIDs
    • Physical therapy
Operative
  • Surgical interventions are based exclusively on the pathology/symptomatology present and the suspected level of nerve compression/involvement
  • Thoracic Outlet Syndrome
    • Excision of any anomalous offending anatomy
    • First rib resection
  • Cervical Radiculopathy
    • Anterior cervical discectomy and fusion
    • Rarely total disc replacement
    • Posterior cervical laminoforaminotomy
  • Carpal Tunnel Syndrome
    • Carpal tunnel release
Outcomes
  • Surgical outcomes are generally considered to be poorer than outcomes for patients with only one site of compression2-3
    • In one study, 33% of patients with CTS and CR considered carpal tunnel release as a failure compared to 7% of those with CTS alone8
  • Patients with DCS may have a suboptimal response to carpal tunnel injection, and this lack of clinical improvement may be used as a predictor for surgical outcomes with carpal tunnel release2
Key Educational Points
  • The term “double crush” may be misleading, as “double” does account for conditions in which ≥3 sites of a given nerve are affected, and “crush” does not account for other mechanical stresses or medical and pharmacological factors that may contribute
  • For these reasons, the term “multifocal neuropathy” has been proposed
  • There is a lack of consistency among studies on DCS, which highlights the complexity of the pathologic processes that contribute to its symptomatology2
  • Multiple studies have failed to recognize an electrodiagnostic correlation between patients with isolated CTS and those diagnosed with DCS 
  • When treating an isolated entrapment like carpal tunnel syndrome, clinicians must always appreciate that the outcome of treatment may be affected by co-existing diseases such as diabetes and cervical arthritis in the case of carpal tunnel syndrome.
References

Cited

  1. Upton AR, McComas AJ. The double crush in nerve entrapment syndromes. Lancet 1973;2(7825):359-62. PMID: 4124532
  2. Kane PM, Daniels AH, Akelman E. Double Crush Syndrome. J Am Acad Orthop Surg 2015;23(9):558-62. PMID: 26306807
  3. Cohen BH, Gaspar MP, Daniels AH, et al. Multifocal Neuropathy: Expanding the Scope of Double Crush Syndrome. J Hand Surg Am 2016;41(12):1171-5. PMID: 27751780
  4. Molinari WJ 3rd, Elfar JC. The double crush syndrome. J Hand Surg Am 2013;38(4):799-801. PMID: 23466128
  5. Toussaint CP, Ali ZS, Heuer GG, Zager EL. “Double Crush Syndrome” in Thoracic Outlet Syndrome (2013). Springer-Verlag: London, UK, pp. 101-104.
  6. Morgan G, Wilbourn AJ. Cervical radiculopathy and coexisting distal entrapment neuropathies: double-crush syndromes? Neurology 1998;50(1):78-83. PMID: 9443461
  7. Baba M, Ozaki I, Watahiki Y, et al. Focal conduction delay at the carpal tunnel and the cubital fossa in diabetic polyneuropathy. Electromyogr Clin Neurophysiol 1987;27(2):119-23. PMID: 3582257  
  8. Osterman AL. The double crush syndrome. Orthop Clin North Am 1988;19(1):147-55. PMID: 3275922

New Articles

  1. Cohen BH, Gaspar MP, Daniels AH, et al. Multifocal Neuropathy: Expanding the Scope of Double Crush Syndrome. J Hand Surg Am 2016;41(12):1171-5. PMID: 27751780
  2. Kane PM, Daniels AH, Akelman E. Double Crush Syndrome. J Am Acad Orthop Surg 2015;23(9):558-62. PMID: 26306807

Review

  1. Molinari WJ 3rd, Elfar JC. The double crush syndrome. J Hand Surg Am 2013;38(4):799-801. PMID: 23466128

Classic

  1. Upton AR, McComas AJ. The double crush in nerve entrapment syndromes. Lancet 1973;2(7825):359-62. PMID: 4124532
  2. Hurst LC, Weissberg D, Carroll RE.: The relationship of double crush syndrome to carpal tunnel syndrome (Analysis of 1,000 cases of carpal tunnel syndrome). J Hand Surg 1985: 10B:202-204. PMID: 4031604
Subscribe to DOUBLE CRUSH SYNDROME
⇡