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18 Lateral Cervical Approach

Amy Fauber and Robert Bergman

Introduction Diagnosis
It is not uncommon for the neurosurgeon to encounter lateralizing Electrodiagnostic evaluation, specifically electromyography (EMG),
disease in the cervical spine. A lateral approach to the spinal cord or may also be used to identify denervation and lesion distribution.
nerve roots can be very useful for intervertebral disc disease, EMG can be used in the determination of neurogenic atrophy from
trauma, neoplasia such as nerve sheath tumors, and other spinal disuse atrophy. This can be helpful when a lameness is difficult to
cord disease such as cervical spondylomyelopathy due to bulbous diagnose. EMG does not preclude imaging [3]. Identification of the
articular facets. Lesions of the cervical spine located in the interver- underlying cause for lateralized clinical signs is generally done by
tebral foramen or spinal nerve root or involving the articular facet advanced imaging (MRI, CT, or CT‐myelography). Survey radiog-
may require a lateral approach. Specifically, portions of the subaxial raphy of the cervical spine for intervertebral disc disease has a low
cervical spine, C3–C4 to C7–T1 present a distinct challenge in sensitivity of about 35% for accurately identifying the location of a
obtaining adequate exposure to the region of interest. disc herniation [4]. Myelography without CT may not identify
intraforaminal discs and it is recommended that when a lateralized
lesion is suspected that CT be used concurrently [5]. CT without
Clinical Evaluation intrathecal contrast may be useful for chondrodystrophic dogs,
Various clinical presentations of animals with a lateralized cervical although a normal study does not rule out the possibility of under-
lesion may be noted. “Root signature” is a commonly encountered lying disease [6]. CT protocols of the cervical spine have been
clinical sign [1]. An animal with this sign may hold up the affected described [7]. MRI characteristics of nerve sheath tumors and
limb periodically. Forelimb lameness may also be a presenting com- intraspinal nerve sheath tumors have been described [8]. Both
plaint. Following a thorough orthopedic examination, a complete types of tumor tend to be most frequently found in the cervical
neurological evaluation is recommended. Careful attention should spine [8,9]. The authors prefer MRI, as it is the most sensitive form
be given to signs of front and pelvic limb lameness, weakness or of imaging for soft tissue and neurological disease processes [10,11].
ataxia that is predominantly one‐sided. In some dogs with a herni-
ated disc located in the intervertebral foramen, episodic pain may
be the only clinical sign noted. Patients may or may not have signifi- Indications for a Lateral Cervical Approach
cant cervical pain on palpation of the spine. Flexor withdrawal Lateral approaches to the cervical spine have been described
should be evaluated in both front limbs. With lesions involving the previously in a limited number of reports [12–14]. Exposure to this
caudal aspect of the cervical spine, flexor withdrawal may be weak, portion of the spine can be technically difficult. This approach may
incomplete, or absent. Some animals exhibit marked hyperesthesia be avoided in favor of a less optimal form of exposure if the
in the affected limb and for these patients generally the lesion local- clinician is not experienced with this surgical approach.
ization will be confined to the C6–T2 spinal cord segments. It has A lateral approach can be particularly helpful for multiple neuro-
been reported that a weak flexor withdrawal may result from a logical diseases that require decompression. Hansen type I interver-
lesion cranial to C6 spinal cord segment [2]. With chronic lesions, tebral disc material will sometimes lodge in the intervertebral
or profound nerve root compression, there may be marked muscle foramen (Figure 18.1). Residual disc within the intervertebral fora-
atrophy of the affected limb. men can serve as a source of ongoing radicular pain. A ventral slot

Current Techniques in Canine and Feline Neurosurgery, First Edition. Edited by Andy Shores and Brigitte A. Brisson.
© 2017 John Wiley & Sons, Inc. Published 2017 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/shores/neurosurgery

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