2 Spine and Spinal Cord

10.1055/b-0039-171764

2 Spine and Spinal Cord

2.1 Key Myotomes and Dermatomes and Their Main Function (Table 2.1)


	Motor	Sensory	Remarks
C2	None	Greater occipital nerve: occiput sensation
C4	Diaphragm	Clavicle	C3–C5 keep the diaphragm alive
C5	Deltoid: arm abduction	Lateral arm	C3–C5 keep the diaphragm alive
C6	Biceps and brachioradialis: forearm flexion	Thumb	Biceps tendon reflex Radioperiosteal reflex
C7	Triceps: forearm extension	Fingers 2 and 3	Triceps tendon reflex
C8	Finger flexors: grip strength	Fingers 4 and 5
T1	Hand intrinsics: finger abduction	Inside of arm and forearm
T4	Intercostals	Nipples
T10	Upper abdominal muscles	Umbilicus	Abdominal cutaneous reflex
T12	Lower abdominal muscles	Belt line	Abdominal cutaneous reflex
L1	Adductors	Groin
L2	Iliopsoas, adductors	Inside thigh	Cremasteric reflex
L3	Adductors, quadriceps	Anterior thigh
L4	Quadriceps	Anterior thigh and shin	Patellar tendon reflex
L5	Foot extensors	Lateral thigh and calf to big toe
L5	CAUTION: L5 radiculopathy: weakness of foot extension (anterior tibialis) + foot inversion (posterior tibialis) + internal rotation of flexed hip (gluteus medius) Peroneal nerve palsy: ONLY foot extensor weakness; the other muscles are spared
S1	Gastrocnemius	Posterolateral calf to little toe	Achilles tendon reflex
S2	Toe flexors	Posterior thigh
S3, S4	Bowel and bladder function	Perianal	Bulbocavernosus reflex

2.2 Spine Injuries

2.2.1 Management of Cervical Spine Fractures (Table 2.2a)

Always Rule Out Vertebral Artery Injury


Fracture	Radiographic appearance	Description	Treatment
Occipital condyle fracture		POTENTIALLY UNSTABLE Anderson and Montesano classification: Type I: comminuted from impact (axial loading) Type II: extension of linear basilar skull fracture Type III: avulsion of bone fragment (rotation, lateral bending) considered unstable CT is diagnostic test of choice supplemental MRI to assess ligaments	Simple unilateral type I or II: collar Bilateral or type III: halo Fracture with ligamentous injury/instability or severe type III: occipitocervical fusion
Atlanto-occipital dislocation (AOD)		UNSTABLE CT is test of choice especially in children Highest sensitivity test is the condyle–C1 interval (CC1): Adults: < 1.4 mm Pediatrics: < 2.5 mm On X-ray or CT, the following may also be used: Basion–axial interval (BAI): Adults: ≤ 12 mm Pediatrics: 0–12 mm but never negative Basion–dental interval (BDI): Adults: ≤ 12 mm Pediatrics: variable because of odontoid ossification stage Powers ratio/Dublin method: have low sensitivity – would avoid using. Posterior axial line (PAL): posterior margin of C2 body Upper cervical prevertebral soft tissue swelling should prompt CT to rule out AOD	Always surgical: occipitocervical fusion, any technique DO NOT USE TRACTION (10% risk of neurological deterioration)
C1 ring fracture (AKA Jefferson’s fracture)	Type 1 Type 2 Type 3	POTENTIALLY UNSTABLE Type 1: single posterior arch fracture Type 2: anterior and posterior ring fractures. Four-point fracture is classic Jefferson’s. Type 3: lateral mass fracture Stability (rule of Spence) depends to a large extent on whether transverse ligament is intact. This can be indirectly assessed by whether the combined overhang of the lateral masses of C1 on C2 is more or less than 7 mm → More than 7 mm implies a disrupted transverse ligament. Obtain MRI to assess.	Type 1: collar Type 2: Intact transverse ligament → halo Disrupted transverse ligament → surgery (C1/C2 fusion or occipitocervical fusion) Type 3: halo
Atlantoaxial rotatory deformity		Grading is based on degree of atlantodental interval (ADI) in the presence of rotation	If transverse ligament is intact or suffers from bony avulsion, attempt reduction through traction followed by halo vest immobilization, Surgery if: irreducible or reduction is not maintained following termination of halo treatment transverse ligament disrupted
	Type 1	POTENTIALLY STABLE Type 1: Anterior subluxation of C1 on C2 Both joints affected Symmetric lateral mass subluxation Pivot point is dens Fixed rotation Transverse ligament intact Normal ADI
	Type 2	POTENTIALLY UNSTABLE Type 2: Anterior subluxation of C1 on C2 Only one joint affected Pivot point is intact joint Transverse ligament disrupted ADI < 5 mm
	Type 3	POTENTIALLY UNSTABLE Type 3: Anterior subluxation of C1 on C2 Both joints affected Asymmetric lateral mass subluxation Asymmetric pivot around dens Transverse ligament disrupted ADI > 5 mm
	Type 4	POTENTIALLY UNSTABLE Type 4: Posterior displacement of C1 on C2
Insufficiency of transverse ligament		ADI 3–5 mm: partial transverse ligament disruption ADI 5–8 mm: complete transverse ligament disruption with low risk of neurological injury ADI > 10 mm: complete ligamentous disruption with high risk of neurological injury	May attempt halo immobilization treatment, if ADI ≤ 5 mm secondary to: purely ligamentous injury or atlantodental instability due to bone evulsion of tubercle where transverse ligament attaches on C1 C1/C2 fusion, if ADI > 5 mm OR because of purely ligamentous injury
Odontoid fracture	Type 1	STABLE Type 1: oblique avulsion fracture through odontoid tip	Rigid collar (nearly 100% success rate)
Odontoid fracture	Type 2	POTENTIALLY UNSTABLE Type 2: fracture through the base of the odontoid Stability depends primarily on whether transverse ligament is intact	Halo immobilization Consider surgery instead of halo if: ≥ 50 years old posterior fracture displacement any fracture displacement > 6 mm angulation > 10° fracture comminution Surgical options: odontoid screw may be used in acute phase C1/C2 transarticular or C1/C2 Harms fusion in acute phase or for pseudoarthrosis Consider cervical collar with goal of “stable non-union” for elderly patients who cannot tolerate surgery or halo
Cont’d	Type 3	STABLE Type 3: Fracture extends into C2 body cancellous bone and may involve C1/C2 joint uni- or bilaterally	Collar (90% success rate) or Halo
Os odontoideum		POTENTIALLY UNSTABLE Significant translation of os anterior or posterior to C2 peg may indicate instability	Observation in case of no symptoms or neurological signs and no instability Surgery in case of symptoms or neurological signs or instability: reducible neurologic compression (via traction etc): reduce and then C1/C2 fusion irreducible ANTERIOR neurologic compression: ventral decompression (transoral, endoscopic transnasal) followed by fusion stabilization for instability irreducible POSTERIOR neurologic compression: posterior decompression (laminectomy) followed by fusion stabilization for instability
Traumatic spondylolisthesis of C2 AKA Hangman’s fracture	Type 1	STABLE Type 1: vertical pars fracture of axis: Displacement of C2 on C3 < 3 mm No angulation	Collar or halo
	Type 2	UNSTABLE Type 2: like type 1 PLUS disruption of C2/C3 disk and posterior longitudinal ligament (PLL): Displacement of C2 on C3 > 3 mm Possible angulation. Mostly displacement rather than angulation	Traction followed by halo
	Type 2a	UNSTABLE Type 2a: oblique pars fracture: Displacement of C2 on C3 < 3 mm Significant angulation > 11 degrees	Reduce via hyperextension and place in situ compression halo CAUTION: avoid traction → may worsen angulation
	Type 3	UNSTABLE Type 3: like type 2 PLUS bilateral facet disruption and possible ALL ligament disruption: Displacement of C2 on C3 > 3 mm Significant angulation > 11 degrees	Open reduction Followed by C2/C3 fusion with lag screws across fracture line
Cervical wedge compression fracture		STABLE, if posterior elements are intact (simple) UNSTABLE, if posterior elements are disrupted (complex)	Simple compression: collar Complex compression: consider treatment with halo or directly proceed with surgical stabilization
Cervical teardrop fracture		UNSTABLE Usually associated with: Anterior inferior bone fragment Posterior displacement of vertebral body into spinal canal Kyphosis (flexion angulation of the spine) Posterior ligamentous disruption May be confused with avulsion fracture. Always obtain CT	Surgical fusion anterior or posterior ± decompression anterior or posterior as needed
Cervical subluxation, locked or jumped facet joints		UNSTABLE Unilateral: Usually < 50% subluxation Clinically: 25% intact 35% root deficit 25% incomplete spinal cord injury 15% quadriplegia Bilateral: Usually > 50% subluxation Clinically: 75% quadriplegia 15% incomplete spinal cord injury 10% intact Imaging: Sagittal CT shows facet dislocation (“bow-tie” sign) Axial CT shows “naked” facet sign	CAUTION: If possible, obtain MRI prior to reduction to rule out disk herniation For patients with neurological deficit, attempt closed reduction with traction followed by surgical stabilization (anterior cervical discectomy and fusion [ACDF] or posterior fusion or both) For patients without neurological deficit, you may proceed with open reduction and arthrodesis: preferred method is by drilling off facet to allow for reduction, followed by posterior instrumented fusion. ACDF with divergent distraction pin placement has also been described as an alternate method for reduction and fusion
Facet separation fracture		POTENTIALLY UNSTABLE Fracture through ipsilateral lamina and pedicle. Floating facet	Consider halo immobilization, if there is: minimal displacement of facet fracture fragments with no other ligamentous injury and no neurologic deficit Otherwise, proceed with surgery. Surgical options: Posterior instrumented fusion from level above to level below without placement of screw into fractured facet. If needed, decompress affected nerve root ACDF may also be considered
Comminuted facet fracture		POTENTIALLY UNSTABLE Multiple fractures of pedicle and within facet. May cause angulation in coronal plane
Split fracture		POTENTIALLY UNSTABLE Unilateral lateral mass fracture. Fracture line is vertical
Traumatic spondylolysis		POTENTIALLY UNSTABLE Bilateral horizontal pars interarticularis fracture Separates anterior from posterior spinal elements
Cervical distraction–extension injuries	Type 2	UNSTABLE Type 1: Fracture through vertebral body or disk space Posterior elements intact Usually presents only with lordotic angulation Type 2: Similar to type 1 but posterior elements are disrupted Usually presents with lordotic angulation and retrolisthesis	Type 1: With fracture through bone: Halo vest With fracture through disc space: ACDF Type 2: A 360-degree circumferential fusion PLUS decompression as needed
Spinous process fracture AKA “clay shoveler’s fracture		STABLE	No specific treatment is necessary: Pain relief Collar for comfort

General Comments on Spine and Spinal Cord Injury (Table 2.2b)


Methylprednisolone: in the 2013 updated guidelines for the management of acute cervical spine and spinal cord injury, the use of methylprednisolone is NOT RECOMMENDED. Timing of surgery: Complete spinal cord injury: surgery as soon as the patient is medically stable (after spinal shock) Goal of surgery: spinal stabilization to allow for sitting position and early rehabilitation Incomplete spinal cord injury: early decompression and stabilization Goal of surgery: functional recovery (spinal cord decompression)

Cervical Spine Closed Reduction Protocol (Table 2.2c)


Rule out skull fractures Always place pins with patient’s eyes closed Closed reduction is contraindicated if MRI shows disk herniation If flexion or extension is necessary during traction, consider external auditory meatus as neutral point Protocol: Start weight: cervical level × 3 in lb Obtain X-ray Increase weight by 5–10 lb every 10–15 min until reduced → Maximum weight in pounds: 5–10 lb × cervical level Check X-ray after every weight increase Once reduction is achieved, leave the patient in traction with 5–10 lb until definitive treatment (surgery or halo vest) Add muscle relaxants, narcotics, or general anesthesia (must use somatosensory evoked potentials [SSEP]/motor evoked potential [MEP])
Stop closed reduction if: Level is reduced Occipitocervical instability develops (condyle–C1 lateral mass distance > 5 mm) Any disc space height > 10 mm (= overdistraction) Neurological or SSEP/MEP deterioration

How to Clear a Cervical Spine (Table 2.2d )


Asymptomatic patient	Patients DO NOT NEED radiographic cervical spine evaluation if: Awake Asymptomatic without neck pain or tenderness Without injury detracting from accurate evaluation Have not received CNS depressant medication or pharmacotherapy for pain Able to complete functional range of motion evaluation
b. Symptomatic patient	Remember: you MUST rule out BOTH bone injury and ligamentous injury! Bone injury is best ruled out by CT: only if negative, proceed to rule out ligamentous injury Ligamentous injury is best ruled out by: MRI with short tau inversion recovery (STIR) images within 48 h after injury OR flexion/extension X-rays once the patient no longer has symptoms or limiting pain
c. Obtunded or unreliable patient	Rule out bone injury with CT: only if negative, proceed to rule out ligamentous injury Rule out ligamentous injury with MRI with STIR images within 48 h after injury If MRI is not available, you may consider manual flexion/extension X-rays under fluoroscopic guidance

2.2.2 Management of Thoracic and Lumbar Spine Fractures (Table 2.3)


Three-column model (DENIS)	Anterior column: Anterior longitudinal ligament (ALL) Anterior 50% of vertebral body and disc
	2. Middle column: Posterior 50% of vertebral body and disk Posterior longitudinal ligament (PLL) 3. Posterior column: Pedicles Posterior bones (laminae, facet joints, spinous processes) Ligaments (ligamentum flavum, interspinous, supraspinous) Facet joint capsule Potentially unstable if: ≥ 2 columns are involved Fracture below T8 and middle column involved Any of the following: loss of height > 50% canal compromise > 50% kyphosis > 20°


Fracture	Radiographic appearance	Description	Treatment
Transverse process fracture		STABLE	No specific treatment necessary. May chose to brace.
Acute traumatic pars interarticularis (uni- or bilateral) fracture without nerve root compression
Laminar fracture
Spinous process fracture
Compression fracture		STABLE Involves anterior column only.	Thoracic lumbar sacral orthosis (TLSO) brace Consider vertebroplasty, if after TLSO brace for 3 mo: the patient continues to have pain without anatomical progression with continued high signal on STIR MRI imaging Consider kyphoplasty or surgical fusion, if after TLSO brace for 3 mo the patient presents with anatomical progression (ie. progressive kyphosis or loss of height)
Burst fracture		POTENTIALLY UNSTABLE Fractures above T8 are more stable because of rib cage support Involves anterior and middle column Most commonly involves superior endplate Less commonly involves inferior endplate or both endplates	In neurologically intact patients: TLSO brace, if there is no evidence of posterior element disruption: Kyphosis < 15° no spinous process or facet splaying no high signal in posterior elements on STIR MRI) Surgical stabilization is recommended, if there is involvement of posterior elements: Kyphosis > 15° Spinous process or facet splaying High signal in posterior elements on STIR MRI In neurologically compromised patients Surgical decompression and stabilization must be performed. i. In thoracic region: anterior compression should be treated with anterior approach ii. In lumbar spine: anterior compression may be reduced with the use of a down-angled curette or via transpedicular approach If posterior stabilization is performed: 2 levels above + 2 levels below fracture is minimum requirement
“Seat belt” fracture AKA Chance fracture		UNSTABLE Distraction of middle and posterior columns No or mild compression of anterior column	In neurologically intact patients with bone injury WITHOUT significant ligamentous injury: place in and reduce with hyperextension cast In neurologically compromised patients or those with bone injury ALONG WITH significant ligamentous injury: proceed with surgical stabilization and decompression if needed
Fracture dislocation		UNSTABLE Failure of all three columns: bone or ligament disruption with displacement	Posterior surgical stabilization with anterior or posterior decompression (corpectomy) if needed

2.2.3 Management of Sacral Spine Fractures (Table 2.4)


Disease	Radiographic appearance	Description	Treatment
Zone 1		Fracture through ala only No involvement of sacral foramina or sacral canal May cause L5 nerve root injury	Consider nonoperative management for: nondisplaced fractures without symptomatic neurological compromise Iliosacral screw stabilization with decompression (as needed) for: significant fracture displacement OR those with neurologic compromise. REMEMBER: Concurrent orthopaedic management required to assess pelvis
Zone 2		Fracture through sacral foramina No involvement of sacral canal May cause unilateral L5, S1, S2 nerve root injuries Usually normal bladder function
Zone 3: vertical		Fracture longitudinally along sacral canal Usually associated with: pelvic ring fracture bladder dysfunction saddle hypesthesia
Zone 3: transverse		Fracture transverses entire sacrum horizontally Usually direct trauma to sacrum Usually associated with: bladder and bowel dysfunction saddle hypesthesia

2.2.4 Penetrating Spine Injuries (Table 2.5)


Indications for surgery	Military weapon: debridement Copper bullet: remove Lead bullet in joint or disc space or bursa Migrating bullet Bullet that traversed gastrointestinal (GI) or respiratory tract: debridement for infection reduction Cerebrospinal fluid (CSF) leak Spinal instability

2.3 Management of Degenerative Cervical Spine Disease (Table 2.6)


Condition	Imaging	Causes, diagnostic tests and other	Treatment
Cervical radiculopathy without myelopathy		Disc herniation Foraminal stenosis	Nonsurgical treatment, if primarily sensory symptoms with no or minimal weakness Treatment options: Oral anti-inflammatory medications Neuropathic pain medications Traction Cervical epidural steroid injections Consider surgical treatment, if: 6 weeks of conservative measures are ineffective or patient initially presents with significant weakness Surgical options for radiculopathy due to foraminal stenosis or disk herniation without significant midline component: Posterior laminoforaminotomy/diskectomy (preferred due to motion segment preservation and lack of need for implant) Anterior cervical discectomy with instrumented fusion or disk replacement is the other option
Cervical myelopathy		Central disc herniation Anterior compression due to spondylotic changes Posterior element compression (ligamentous hypertrophy or spondylotic changes) For diagnostic verification of myelopathy, preoperative SSEP may be considered	Myelopathy = surgery! Predictors of poor prognosis: Older age Symptoms duration > 1 – 2 y Poor preoperative status Spinal cord signal (↓T1 and ↑T2) Spinal cord atrophy Surgical options depending on compressive pathology: Disc herniation: Disc herniation 1–3 levels → anterior decompression and stabilization Disc herniation > 3 levels with preserved lordosis → posterior decompression ± instrumented fusion Anterior spondylotic compression: Consider corpectomy with anterior fusion. Consider augmenting anterior fusion with posterior instrumented fusion, if corpectomy involves ≥ 2 vertebral bodies. Consider posterior decompression ± instrumented fusion in patients with preserved lordosis Posterior element compression: posterior decompression ± instrumented fusion CAUTION: posterior decompression without fusion carries an increased risk of instability and kyphosis. Posterior instrumented fusion or laminoplasty may be used in order to reduce this risk. CAUTION: C5 palsy in 5% of posterior decompressive surgeries. Consider steroid tapper. Prognosis is good (may take several months to improve).
Ossified PLL (OPLL)		More common: Asian population Males Age > 50 y	Asymptomatic patients: observation Patients with radicular symptoms ONLY: treat with laminoforaminotomy Patients with myelopathy ± radicular symptoms. Neutral or lordotic cervical spine: preferred approach is posterior indirect decompression ± instrumented fusion Kyphotic cervical spine: i. anterior decompression with epidural dissection using microscope ii. If > 2 level corpectomy is performed, augment anterior fusion with posterior instrumented fusion REMEMBER: It is preferable to avoid anterior approaches because of the increased risk of CSF leak and anterior spinal artery injury
Cervical kyphosis		Common causes: Degenerative Iatrogenic (post-laminectomy)	Cord compression due to kyphosis ONLY: i. If kyphosis is reducible: Reduce with traction, followed by Posterior instrumented fusion ii. If kyphosis cannot be reduced: Ankylosed posterior elements: Posterior release/facetectomy ± Anterior release (ACD/corpectomy/fusion), if facet ectomy does not provide enough lordosis + Posterior instrumented fusion Non-ankylosed posterior elements: i. Anterior release (ACD/corpectomy/fusion) to create lordosis ii. ± Posterior instrumented fusion Cord compression due to kyphosis PLUS significant anterior compressive pathology (osteophytes, etc.): Careful with closed reduction!! i. If kyphosis is reducible: Start with anterior decompression (ACD/corpectomy/fusion), ± Posterior instrumented fusion in reduced lordosed position ii. If kyphosis cannot be reduced: Ankylosed posterior elements: Start with anterior decompression (ACD/corpectomy/fusion), because anterior compression is significant Posterior release/facetectomy Plus posterior instrumented fusion Non-ankylosed posterior elements: Start with anterior decompression (ACD/corpectomy/fusion) ± Posterior instrumented fusion


Condition	Anatomy	Causes, diagnostic tests and other	Treatment
Central cord syndrome		Typical presentation: Motor deficit is greater in upper extremities than in lower ± Sensory deficit below injury ± Bowel and bladder dysfunction	In the absence of compression/instability: patient may be treated conservatively If compression and instability are present: i. Patient with deteriorating neurological status: urgent surgery is recommended → anterior or posterior approach ± fusion (depending on the pathology and instability) ii. Patient with a stable or improving neurological deficit: elective surgery is recommended → anterior or posterior approach ± fusion (depending on pathology and instability)
Rheumatoid arthritis		Erosion of odontoid and pannus formation behind C2 Basilar invagination secondary to erosive destruction of lateral masses C1	Asymptomatic patients: there are no guidelines for prophylactic surgery Symptomatic patients: i. Compression due to basilar invagination only: attempt to reduce patients with traction If reducible → proceed with occipitocervical (OC) fusion If irreducible → consider transoral decompression followed by OC fusion ii. Compression due to pannus formation only: transoral decompression → followed by C1/C2 fusion or OC fusion There is evidence that in some cases OC fusion alone leads to involution of pannus iii. If both are present: traction + transoral decompression + OC fusion