Heuristic map of myotomal innervation in humans using direct intraoperative nerve root stimulation

Clinical article

Clemens M. Schirmer Division of Neurosurgery, Baystate Medical Center, Springfield;
Tufts University School of Medicine, Boston;

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 M.D.
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Jay L. Shils Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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 Ph.D.
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Jeffrey E. Arle Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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G. Rees Cosgrove Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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 M.D.
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Peter K. Dempsey Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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Edward Tarlov Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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Stephan Kim Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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 M.D.
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Christopher J. Martin Impulse Monitoring, Columbia, Maryland

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 B.S.
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Carl Feltz Impulse Monitoring, Columbia, Maryland

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 Au.D.
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Marina Moul Impulse Monitoring, Columbia, Maryland

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 B.S.
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Subu Magge Department of Neurosurgery, Lahey Clinic, Burlington, Massachusetts; and

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Object

Considerable overlap exists in nerve root innervation of various muscles. Knowledge of myotomal innervation is essential for the interpretation of neurological examination findings and neurosurgical decision-making. Previous studies relied on cadaveric dissections, animal studies, and cases with anomalous anatomy. This study investigates the myotomal innervation patterns of cervical and lumbar nerve roots through in vivo stimulation during surgeries for spinal decompression.

Methods

Patients undergoing cervical and lumbar surgeries in which nerve roots were exposed in the normal course of surgery were included in the study. Electromyography electrodes were placed in the muscle groups that are generally accepted to be innervated by the roots under study. These locations included levels above and below the spinal levels undergoing decompression. After decompression, a unipolar neural stimulator probe was placed directly on the nerve root sleeve and constant current stimulation in increments of 0.1 mA was performed. Current was raised until at least a 100 μV amplitude–triggered electromyographic response was noted in 1 or more muscles. All muscles that responded were recorded.

Results

A total of 2295 nerve root locations in 129 patients (mean age 57 ± 15 years, 47 female [36%]) were stimulated, and 1589 stimulations met quality criteria and were analyzed. Four hundred ninety-five stimulations were performed on roots contributing to the cervical and brachial plexus from C-3 to T-1 (31.2%), and 1094 (68.8%) were roots in the lumbosacral plexus between L-1 and S-2. The authors were able to construct a statistical map of the contributions of each cervical and lumbosacral nerve root for the set of muscle groups monitored in the protocol. In many cases the range of muscles innervated by a specific root was broader than previously described in textbooks.

Conclusions

This is the largest data set of direct intraoperative nerve root stimulations during decompressive surgery, demonstrating the relative contribution of root-level motor input to various muscle groups. Compared with classic neuroanatomy, a significant number of roots innervate a broader range of muscles than expected, which may account for the variability of presentation between patients with identical number and location of compressed roots.

Abbreviation used in this paper:

EMG = electromyography.
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  • 1

    Chotigavanich C, & Sawangnatra S: Anomalies of the lumbosacral nerve roots. An anatomic investigation. Clin Orthop Relat Res 278:4650, 1992

  • 2

    Dykes RW, & Terzis JK: Spinal nerve distributions in the upper limb: the organization of the dermatome and afferent myotome. Philos Trans R Soc Lond B Biol Sci 293:509554, 1981

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 3

    Foerster O: The dermatomes in man. Brain 56:139, 1933

  • 4

    Head H, & Campbell AW: The pathology of Herpes Zoster and its bearing on sensory localization. Brain 23:353523, 1900

  • 5

    Henderson CM, , Hennessy RG, , Shuey HM Jr, & Shackelford EG: Posterior-lateral foraminotomy as an exclusive operative technique for cervical radiculopathy: a review of 846 consecutively operated cases. Neurosurgery 13:504512, 1983

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 6

    Jensen OH: The level-diagnosis of a lower lumbar disc herniation: the value of sensibility and motor testing. Clin Rheumatol 6:564569, 1987

  • 7

    Kadish LJ, & Simmons EH: Anomalies of the lumbosacral nerve roots. An anatomical investigation and myelographic study. J Bone Joint Surg Br 66:411416, 1984

  • 8

    Kikuchi S, , Hasue M, , Nishiyama K, & Ito T: Anatomic and clinical studies of radicular symptoms. Spine (Phila Pa 1976) 9:2330, 1984

  • 9

    Levin KH, , Maggiano HJ, & Wilbourn AJ: Cervical radiculopathies: comparison of surgical and EMG localization of single-root lesions. Neurology 46:10221025, 1996

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 10

    Marinacci AA: A correlation between the operative findings in cervical herniated discs with the electromyograms and opaque myelograms. Electromyography 6:523, 1966

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 11

    Phillips LH II, & Park TS: Electrophysiologic mapping of the segmental anatomy of the muscles of the lower extremity. Muscle Nerve 14:12131218, 1991

  • 12

    Reihani-Kermani H: Correlation of clinical presentation with intraoperative level diagnosis in lower lumbar disc herniation. Ann Saudi Med 24:273275, 2004

  • 13

    Sharrard WJ: The distribution of the permanent paralysis in the lower limb in poliomyelitis; a clinical and pathological study. J Bone Joint Surg Br 37-B:540558, 1955

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 14

    Sherrington CS: Notes on the arrangement of some motor fibres in the lumbosacral plexus. J Physiol (Lond) 13:621772, 1892

  • 15

    Thage O: The myotomes L2—S2 in man. Acta Neurol Scand Suppl 13:241243, 1965

  • 16

    Tsao BE, , Levin KH, & Bodner RA: Comparison of surgical and electrodiagnostic findings in single root lumbosacral radiculopathies. Muscle Nerve 27:6064, 2003

  • 17

    Wittenberg RH, , Lütke A, , Longwitz D, , Greskötter KH, , Willburger RE, & Schmidt K, et al.: The correlation between magnetic resonance imaging and the operative and clinical findings after lumbar microdiscectomy. Int Orthop 22:241244, 1998

    • PubMed
    • Search Google Scholar
    • Export Citation
  • 18

    Young A, , Getty J, , Jackson A, , Kirwan E, , Sullivan M, & Parry CW: Variations in the pattern of muscle innervation by the L5 and S1 nerve roots. Spine (Phila Pa 1976) 8:616624, 1983

    • PubMed
    • Search Google Scholar
    • Export Citation

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