Miller-Spine Flashcards
Key aspects of the spine physical examination
Cervical Neurologic Examination
Findings in Cervical Compression
Findings in Lumbar Compression
Lower Extremity Neurologic Exam
Cervical Spine Anatomy
Review Cervical Myelopathy
Spinal cord compromise without reference to specific pathologic entity
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Presenting symptoms can be subtle
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Finger clumsiness, deterioration of handwriting, difficulty in fine motor control of hands, weakness of pinch
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Ataxia with wide-based gait, leg heaviness, and inability to perform tandem walk
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Urinary retention, urgency, or frequency
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Lower extremity weakness (corticospinal tracts) can be associated with worse prognosis.
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Natural history of cervical spondylotic myelopathy is characterized by one of three presentations:
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Stepwise deterioration in symptomatology followed by a period of stability (most common, 65%–80%)
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Slowly progressive decline (over months to years, 20%–25%)
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Rapidly progressive decline (over days to weeks, 3%–5%)
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Physical examination
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Upper motor neuron findings in myelopathy
Myelopathy hand and the finger escape sign (small finger spontaneously abducts because of weak intrinsic muscles)
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Hyperreflexia, Hoffmann sign, clonus, or Babinski sign
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Inverted radial reflex (ipsilateral finger flexion when brachioradialis reflex being elicited)
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Funicular pain—central burning and stinging with or without L’hermitte sign (radiating lightning-like sensations down the back with neck flexion)
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Upper motor neuron findings not always present in all patients
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Upper extremities may have radicular (lower motor neuron) signs along with evidence of distal myelopathy.
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Treatment
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Nonsurgical treatment—NSAIDs, cervical epidural injections, isometric exercises, traction, and occasionally temporary collar immobilization
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Surgical indications—natural history of myelopathy is typically progressive; therefore surgical decompression is frequently indicated.
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Procedures
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Anterior procedures include ACDF versus ACCF or combination (hybrid). Anterior-based procedures are options for patients with either kyphotic or lordotic cervical sagittal alignment.
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Posterior options include laminectomy and fusion versus laminoplasty. Posterior-based options are contraindicated in patients with fixed cervical kyphosis owing to the surgical inability to indirectly decompress the spinal cord.
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Combined anterior and posterior procedures (circumferential surgery). Considered for patients requiring multilevel corpectomy resection with strut reconstructions (highly unstable spine).
Common measurements in C1-C2 disorders
Rheumatoid Cervical Spine
Overview
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Less common owing to improvement and increased use of disease-modifying antirheumatic drugs (DMARDs)
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Patients with rheumatoid arthritis (RA) should undergo flexion/extension radiography before elective surgery.
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When spine is involved, cervical spine, more specifically occipitoatlantoaxial joint (O–C2), is site most commonly affected.
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Atlantoaxial subluxation (AAS)—typically the first manifestation of cervical instability in rheumatoid patient
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Atlantoaxial invagination (AAI)—typically occurs next, after AAS
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Subaxial subluxation (SAS)—usually occurs after AAS and AAI
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Occurs in up to 90% of patients with RA and is more common with long-standing disease and with multiple joint involvement
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Presenting complaints
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Axial neck pain
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Stiffness
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Occipital headaches
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Due to erosion of the C1–2 joint, with subsequent compression of greater occipital branch of C2 nerve
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Results more specifically in pain in posterior aspect of base of skull that is typically relieved with manual traction
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Myelopathy, radiculopathy, or myeloradiculopathy, depending on neurologic structures at risk
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Physical examination
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Subtle signs of neurologic involvement should be sought.
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Neurologic impairment (weakness, decreased sensation, hyperreflexia) in patients with RA usually occurs gradually and is often overlooked or attributed to other joint disease.
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Neurologic impairment with RA has been classified by Ranawat (Table 8.6).
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Imaging
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Radiographic markers are assessed for indications of impending neural compression (Fig. 8.8).
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Anterior atlantodens interval (AADI), frequently referred to simply as atlantodens interval (ADI)
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Posterior ADI (PADI), sometimes also referred to as space available for the cord (SAC)
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MRI
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Cervicomedullary angle (CMA) (Fig. 8.9) is measured by drawing a line along anterior aspect of cervical spinal cord and the medulla.
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Normal: 135–175 degrees
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In patients with progressive superior migration of the odontoid, the CMA decreases owing to draping of the brainstem over the odontoid.
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Reduced CMA has an increased association with respiratory dysfunction and sudden death.
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Atlantoaxial subluxation (AAS)
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Typically first stage of cervical spine involvement in the rheumatoid patient
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Occurs in 50%–80% of patients with RA
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Often the result of pannus formation at synovial joints between the dens and ring of C1, resulting in destruction of transverse ligament, dens, or both
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Leads to instability between C1 and C2, with subsequent subluxation
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Diagnosis
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Anterior subluxation of C1 on C2 is the most common finding, but posterior and lateral subluxation can also occur.
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Findings on examination may include limitation of motion, upper motor neuron signs, and weakness.
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Plain radiographs that include patient-controlled flexion and extension views are evaluated to determine AADI as well as PADI.
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Instability is suggested by AADI motion of more than 3.5 mm on flexion and extension views, although radiographic instability in RA is common and not necessarily an indication for surgery.
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PADI less than 14 mm may be more sensitive than AADI measurement for spinal cord compression in patients with RA.
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Surgical indications
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Intractable pain
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Progressive neurologic instability, cervical myelopathy
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Can be due to mechanical instability
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Direct compression by pannus of C2
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Mechanical instability; evaluation of C1–2 motion/relationship
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AADI greater than 9–10 mm
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PADI less than 14 mm
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PADI may be more sensitive for identifying patients at increased risk of neurologic injury
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PADI less than 14 mm usually requires surgical treatment.
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Surgery is less successful in patients with Ranawat grade IIIB neurologic impairment but should still be considered.
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Treatment
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Surgical fixation
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Gallie fusion—mostly of historical significance
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Brooks fusion—mostly of historical significance and rarely used alone
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C1–2 transarticular screw fixation (Magerl)
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Still used but less commonly since advent of C1–2 Harms construct (see later)
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Requires preoperative CT to evaluate position of vertebral arteries
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Requires reduction of C1–2 joint
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Poses increased risk for vertebral artery and C2 nerve injury
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C1 lateral mass—C2 pedicle/pars fixation (Harms construct)
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Lower rate of vertebral artery and C2 nerve injury
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Biomechanically strongest construct of C1–2 fixation techniques
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Does not require reduction of C1–2 joint
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Odontoidectomy
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Should be reserved as a secondary procedure
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Anterior cord compression by pannus often resolves after posterior spinal fusion.
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AAI
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Also known as cranial settling, basilar invagination, cranial invagination, and other names.
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Second most common manifestation of RA in cervical spine
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Occurs in 40% of patients with RA
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Results in cranial migration of the dens from erosion and bone loss between the occiput and C1–2
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Often seen in combination with fixed atlantoaxial subluxation
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Measurements are shown in Fig. 8.8.
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Landmarks may be difficult to identify.
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Ranawat line is most reproducible.
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Diagnosis
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Progressive cranial migration of dens
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Findings on examination may include limitation of motion, upper motor neuron signs, weakness, and, in severe cases, bulbar symptoms.
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Surgical indications
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Intractable pain
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Progressive cranial migration or neurologic compromise may require operative intervention (occiput–C2 fusion).
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Cervicomedullary angle less than 135 degrees (on MRI) suggests impending neurologic impairment.
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Treatment
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Occipitocervical fusion
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Typically from occiput to C2
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Gentle traction to help bring odontoid process out of foramen magnum
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Transoral or retropharyngeal odontoid resection for persistent brainstem compression after occiput–C2 fusion.
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SAS
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Occurs in 20% of cases of RA
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Seen in combination with upper cervical spine instability
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Pathoanatomy
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Pannus formation in uncovertebral joints (joints of Luschka) and facet joints. Subluxation may occur at multiple levels.
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Radiographic markers of instability
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Subaxial subluxation of greater than 4 mm or more than 20% of the body is indicative of cord compression.
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A cervical height index (cervical body height/width) of less than 2.00 approaches 100% sensitivity and specificity in predicting neurologic compromise.
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Surgical indications
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Intractable pain
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Progressive neurologic compromise, cervical myelopathy
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Mechanical instability—subluxation greater than 4 mm
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Procedure
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Posterior spinal fusion with or without decompression
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Fusion to the most distal unstable level.
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Occiput and/or C1–2 joint included if AAI or AAS exists.
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Anterior spinal fusion
May be required to restore sagittal alignment
May be necessary to increase likelihood of fusion on multilevel posterior spinal fusion
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Surgery may not reverse significant neurologic deterioration, especially if a tight spinal canal is present, but can stabilize it.
What is the cervicomedulary angle and what does it mean
an angle less than 135 degrees on MRI suggests impending neurologic impairment
what is the cervical height index?
Diagram of the cervical nerve root orientation
Diagram of the lumbar nerve root orientation
Anterior soft tissue shadows normal numbers for trauma evaulation:
6mm C2
20mm C6
Review the ASIA classification
Review incomplete spinal cord injuries
Central cord syndrome
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Most common incomplete spinal cord syndrome
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Typical mechanism is hyperextension with preexisting canal stenosis.
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Cord is compressed anteriorly by osteophytes and posteriorly by the infolded ligamentum flavum.
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Cord is injured in the central gray matter, resulting in proportionately greater loss of motor function to upper extremities than to lower extremities.
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The upper extremity is affected more than the lower extremity.
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Variable sensory sparing
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The prognosis is good for the recovery of ambulation, but the patient is less likely to recover upper extremity function.
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Anterior cord syndrome (spinothalamic tract injury)
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The second most common incomplete cord injury
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No typical mechanism for injury
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Direct compression to anterior spinal cord
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Less commonly, vascular injury to anterior spinal artery, or spinal cord ischemia (e.g., anterior spinal artery, artery of Adamkiewicz)
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Damage is primarily in the anterior two-thirds of the cord.
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Loss of motor response, pain reception, and temperature reception below the level of injury
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Patients demonstrate greater motor loss in the legs than the arms.
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Preservation of posterior/dorsal column; vibration sensation, proprioception, and deep pressure sensation intact
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The prognosis for motor recovery is poor.
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Brown-Séquard syndrome (spinal cord hemisection)
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Typical cause is penetrating trauma.
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Ipsilateral loss of motor and loss of position/proprioception function on the side of injury
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Contralateral loss of pain and temperature to the side of injury (usually one to two levels below the insult)
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Best prognosis for recovery of ability to walk (90%)
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Posterior cord syndrome
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Very rare; least common incomplete spinal cord pattern
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Injury to posterior/dorsal column—loss of proprioception, vibrator sensation, and deep pressure sensation
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Preservation of anterior column; motor response, pain reception, and temperature reception intact
Review the safe zones for halo pin placement:
Adults: 4 pins at 6 to 8 inch-lb pressure; children: 8 to 10 pins at 2 inch-lb pressure
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Complications—pin loosening, pin infection, pressure sores, nerve injury, dural penetration
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Gardner-Wells (GW) tongs
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Can be used more acutely to realign the spine in the patient with a displaced fracture with or without neurologic injury
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Pins parallel to the external auditory meatus approximately 1-cm above pinna
What are the absolute contraindications to giving high dose steroids for a spinal cord injury
Penetrating spinal wounds, particularly gunshot wounds
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Injury more than 48 hours old
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Peripheral nerve injuries such as brachoplexopathy, stingers, root level injuries, cauda equina
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Pregnancy
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Age younger than 13 years
key facts about rehab after spinal cord injury
Functional level determined by both sensory and motor level as dictated by
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Most distal intact functional sensory level and
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Most distal motor level where motor grade is 4 or greater
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Respiratory function by level of cord injury
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C1–2 injury
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Vital capacity only 5%–10% of normal
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Ventilator dependence
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Cough absent
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C3–5 injury
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Vital capacity 20% of normal
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Cough weak and ineffective
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Lower cervical and upper thoracic injury
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Vital capacity 30%–50% of normal
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Cough weak but may be effective
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T11 injury and below
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Respiratory dysfunction minimal
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Vital capacity near normal
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Cough strong
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Mobility and function determined by highest motor level
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C3 or above—respiratory dependent
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C4—transfer dependent
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C5—transfer assist
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C6—independent transfers
Activities of daily living
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C6—independent grooming and dressing; can operate flexor hinge wrist-hand orthosis
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C7—able to use knife to cut food
key testable components about a syrinx
Introduction
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Confluent collection of abnormal CSF within the spinal cord
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In regard to orthopaedic spine, most common etiology is posttraumatic syrinx and secondary to herniated disc.
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Other primary causes of spinal syringomyelia include postinflammatory, arachnoid abnormalities (arachnoid cyst), tumor, and idiopathic.
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Syringomyelia can also be related to abnormalities of the foramen magnum: tonsillar descent (Chiari malformation), arachnoid veil with fourth ventricle outlet obstruction.
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Differentiating syringomyelia from hydromyelia
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Hydromyelia—confluent CSF cavity within spinal cord that is a remnant of central canal of spinal cord
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Typically considered a normal variant
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Spinal cord typically not expanded by hydromyelia and therefore not associated with symptoms and not considered a pathologic entity
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Differentiating syringomyelia from spinal cord edema
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Spinal cord edema is increased fluid that is interstitial, and not a confluence of fluid.
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Edema can be secondary to spinal cord contusion or tumor-associated cyst.
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Presentation
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Variable but typically due to the etiology of the syrinx and its associated pathophysiology
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Symptoms associated with partial CSF obstruction (e.g., tussive headaches, strain-related activities)
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Symptoms related to brainstem compression (e.g., swallowing difficulty, voice changes, nystagmus, ataxia, sleep apnea)
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Symptoms related to syringomyelia (e.g., sensory loss [upper greater than lower typically], upper extremity weakness, hand and upper extremity atrophy, gait impairment, lower extremity spasticity, bowel and bladder dysfunction, dysesthetic pain)
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Imaging
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MRI is method of choice
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Does not disrupt CSF dynamics
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T1-weighted image demonstrates intramedullary fluid-filled cavity.
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MRI with gadolinium necessary to rule out possibility of associated spinal tumor.
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T2-weighted images may help identify anatomic detail such as septa in the subarachnoid space.
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CT myelogram
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May have a role in determining obstructive arachnoid disease
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In these cases, performing myelography puncture at C1–2 rather than using lumbar route may allow for pooling of the contrast at the level of the web.
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This pooling may not be seen if contrast is introduced from the lumbar route, because the obstructive subarachnoid web acts as a one-way valve.
C1 injury
A sum of 6.9 is indicative of injury
C2 Odontoid Fractures
Type I—avulsion of alar ligaments from the tip
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Type II—fracture at the base of odontoid
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Type IIA—comminuted fracture of the base of odontoid
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Type III—fractures that extend into the body of C2
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Treatment
Operative indications—based on risk of development of nonunion. Risk factors for nonunion in type II
Displacement greater than 5 mm
Posterior displacement
Age greater than 40 years
Delayed treatment
Angulation greater than 10 degrees
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Type I—immobilization in rigid cervical orthosis
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Type II and IIA
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Nondisplaced—immobilization in rigid cervical orthosis (controversial)
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Displaced types II and IIA fractures are generally considered to require operative treatment because of the high rate of nonunion with nonoperative treatment.
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Type III—typically high incidence of union; most heal in rigid external cervical orthosis. Operative treatment considered if initial displacement greater than 5 mm.
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Procedures
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Posterior C1–2 fusion
Direct osteosynthesis—anterior odontoid screw (Fig. 8.33)
Fracture must be reducible. Nonreduced fracture is a contraindication to anterior odontoid screw.
Fracture geometry must be favorable: anterior superior to posterior inferior (posterior oblique pattern) (Fig. 8.34)
This procedure is associated with a higher failure rate than posterior fusion but theoretically preserves atlantoaxial motion.
Complications
Overall nonunion rate for type II: approximately 32%
Patients older than 80 years do poorly whether treatment is operative or nonoperative.
Airway problems postoperatively or with halo vest immobilization
C2 Body Fracture:
Hangmans
Type I—minimally displaced fracture of the pars secondary to hyperextension and axial loading (<3 mm displacement, no angulation)
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Type IA—same as type I except fracture lines are asymmetric
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Type II—displaced fractures (>3 mm) of the pars, with subsequent flexion after hyperextension and axial loading
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Type IIA—flexion without displacement; care must be taken not to mistake this for a type I fracture, which represents total disc avulsion, because traction may worsen a type IIA fracture.
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Type III—bilateral pars fracture with bilateral facet dislocations (rare)—mechanism is flexion-distraction followed by hyperextension
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Treatment
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Type I—rigid cervical orthosis
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Type II—operative; typically C1–2 fixation or direct osteosynthesis
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Type IIA—halo vest or surgery (no traction)
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Type III—generally operative, usually C2–3 fusion (may require C1–3 fixation, depending on comminution of pars and quality of fixation into C2)
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Complications—vascular injury; vertebral artery injury is rare but increasingly diagnosed by MR angiogram.
Surgical Techniques of C1-C2 Fusion
C1–2 modified Gallie fusion
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Autograft iliac crest placed over C2 spinous process and against posterior arch of C1
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Held in place by sublaminar wire under arch of C1 and under spinous process of C2 (total of one sublaminar wire)
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C1–2 Brooks fusion
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Two separate iliac crest autografts placed between C1 and C2
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One sublaminar wire is placed on either side (total of two sublaminar wires).
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C1–2 transarticular (Magerl) screws
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Preoperative CT scan to assess for location of vertebral artery at C1–2 junction is imperative.
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Adequate intraoperative radiographs are required, or the technique should not be used.
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Cannulated screw is placed under fluoroscopic guidance over a guidewire.
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Screw is placed through the C1–2 facet joint (transarticular), thereby coupling C1–2.
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C1 lateral mass–C2 pedicle (Harms) screws
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C1 screws are placed through the lateral masses. Starting point of the screw is the center of the lateral mass.
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C2 screws are placed traditionally as pedicle screws. In the case of aberrant vertebral artery a shorter, more straight-ahead pars screw can be used in C2 instead.
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Complications
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Vertebral artery may be injured as it runs in the transverse foramen of C2 or as it lies on the superior aspect of C1 in the groove/sulcus of the vertebral artery.
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C2 (greater occipital) nerve lies just dorsal to the C1–2 joint. Injury can result in numbness in the posterior aspect of the skull.
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Neurologic injury
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Dural leaks
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Nonunion/malunion
Review the SLIC
Based on three separate injury axes
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Fracture morphology
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Discoligamentous complex (DLC) integrity
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Neurologic status
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Scoring
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Each axis considered an independent determinant for prognosis and management
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Each axis receives numerical score, with increasing severity receiving a higher numerical value
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No set value defined as requiring surgical treatment; however, higher numerical values suggest increased need for operative intervention
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Treatment goals
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Address neurologic deficits.
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Typically, approach is selected according to location of compression.
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Anterior cervical discectomy and/or corpectomy for anterior compression
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Posterior laminectomy for posterior compression
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Restoring spinal alignment can help through indirect decompression.
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Achieve immediate stability and long-term fusion. Approach varies depending on injury pattern and presence of associated neurologic instability.
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Restore spinal alignment.
