EM guidemap - Spinal cord syndromes

Introduction

Spinal cord anatomy and topographical pathophysiology

• anterior cord syndrome
• central cord syndrome
• posterior cord syndrome
• Brown-Sequard syndrome
• inferior cord (conus medullaris) syndrome
• cauda equina syndrome
• syringomyelia

Clinical clues and clinical spinal cord syndromes

• differential diagnosis of spinal cord syndromes

Appendix

• motor testing
• grading of motor strength
• sensory dermatomes
• somatotopic anatomy of the spinal cord
• summary of the clinical features of some spinal cord syndromes
• evolution of chronic central cord syndrome

Introduction

- this guidemap offers simple clinical advice and basic pathophysiology algorithms that may help a clinician problem-solve spinal cord syndromes in an ED setting

- this guidemap provides no clinical information on diagnostic testing or the treatment of any spinal cord diseases; it is merely a basic guidemap that may help you improve your diagnostic skills in detecting spinal cord syndromes
 

Spinal cord anatomy and topographical pathophysiology

- the spinal cord extends from the foramen magnum to the L1/2 level and pathology of the spinal cord mainly produces symptoms and signs due to the involvement of 3 main areas of the spinal cord - the dorsal columns, the spinothalamic tracts, and the corticospinal motor tracts

- the dorsal columns contain sensory tracts for crude touch, position sense and vibration sense; the lateral spinothalamic tracts contain sensory tracts for pain and temperature and light touch; and the anterior spinothalamic tract contains sensory tracts for touch and pressure

- the antero-lateral corticospinal tracts carry descending motor pathway fibres

Dorsal columns

- consist of sensory tracts carrying information about crude touch-pressure, two point discrimination, vibration and position sense to the brain - on the ipsilateral side of the spinal cord => the fibres cross to the opposite side at the level of the medulla

- crude touch fibres also cross the midline to enter the contralateral anterior spinothalamic tracts and dysfunction of the dorsal column may not produce a detectable disturbance in touch sensation => testing crude light touch sensation is a poor technique for localising spinal cord dysfunction and should not be used in the sensory examination as a discriminatory test

- vibration sense is also carried in several pathways and its absence cannot be regarded as specific evidence of dorsal column pathology

- vibration sense testing is also potentially inaccurate with regards to unilateral or bilateral localisation when testing is performed along the central trunk (eg. pelvis, ribs and sternum), and some elderly patients normally have poor vibration sense perception

- testing joint position sense is the best test of dorsal column function - testing is usually performed by moving the DIP joints of the fingers and toes through a ~ 10 - 20° angle ROM  (holding the finger along the sides of the middle and distal phalanges) => flexing/extending the ankles and wrists is only useful for detecting more gross deficits

- disease affecting the dorsal columns often produces unpleasant deep sensations and buzzing paresthesias or negative sensations of "deadness" and these symptoms often precede detectable abnormal sensory signs; the "deep" sensations are not necessarily of localising value and patients may often complain that parts of the neuro exam (eg, stroking the foot to elicit the plantar response or bending the digits to test position sense) are unusually painful or uncomfortable

- abnormal "deep" sensations include unpleasant vibrating paresthesias - like touching an electric typewriter, standing on the vibrating deck of a ship', tight band-sensations around the torso, bizarre perceptions of body image

Lateral spinothalamic tract

- pain and temperature fibres enter the spinal cord and then ascend a few spinal segments before crossing to travel up the contralateral lateral spinothalamic tract

- local pathology of the spinal cord affecting the spinothalamic tract will therefore produce a contralateral pain and temperature sensory deficit and there will be a difference of a few spinal dermatome levels between the level of detectable sensory deficit and the true level of spinal pathology

- temperature testing is rarely necessary (and is of poorer localising value because some temperature fibres are carried in the contralateral spinothalamic tract) and testing for pain sensation is the best method of assessing the function of the lateral spinothalamic sensory tract

- pain testing should be performed with a broken Q tip handle (or broken tongue blade) using the sharp pointed end of the splintered Q tip/blade to test for pain sensation (remember to specifically ask the patient whether he feels "pain" and not merely "touch"; the blunt end of the stick can be used for crude touch comparison testing)

- disease of the central cord can affect the pain-temperature sensory fibres crossing the midline anterior to the central canal and produce a unilateral or bilateral band of pain-temperature sensory deficit affecting a few dermatomes just below the level of the spinal cord lesion => this band of abnormal sensation can sometimes be unilateral and it may be opposite the side of the major pain-temperature sensory deficit if the spinal cord lesion eventually extends to affect the ipsilateral spinothalamic tract

- as sensory fibres cross the spinal cord and enter the spinothalamic tract they push the already-entered sensory fibres laterally => the sacral sensory fibres are therefore situated most laterally in the spinothalamic tract => central cord disease impinging on the spinothalamic tract in the cervical area may mainly affect pain-temperature sensation arising from the upper limbs and trunk and spare the sacrum => this pattern of sensory deficit can help localise a spinal cord lesion to the cervical central cord; also, never conclude that a spinal cord lesion is complete if sacral pain-temperature sensation is still present (sacral-sparing always suggests incomplete spinal cord pathology)

(* see the appendix for a diagram of the somatotopic anatomy of the spinal cord)

- pathology affecting the spinothalamic tract often produces vague sensory symptoms (very deep, poorly localised pain of a nagging or boring quality) well before a detectable sensory deficit is present - the symptoms are "deep" unpleasant sensations and not sensations of numbness (when a patient complains of numbness - he is usually referring to the 'heavy' feeling associated with weakness and he is not usually referring to a true loss of sensation)

- these unpleasant symptoms may become more dramatic as time progresses and may suggest a psychological disorder to the unwary clinician

- the patient may also have a "loss of feeling" detectable on examination without the patient being previously aware of any sensory deficit

- sensory testing is fraught with potential misinterpretations because mild sensory deficits are difficult to distinguish from genuine physiological differences

- testing for a sensory level is more accurate when moving from an area with a sensory deficit to a normal area, than vica versa

Lateral corticospinal tract

- pathology affecting the upper motor neuron fibres travelling in the corticospinal tract produces an ipsilateral motor deficit

- chronic pathology affecting the corticospinal tract produces signs of an UMN lesion (spasticity + clonus + hyperreflexia + positive Babinski response) long before it produces detectable muscle weakness => the patient will complain of clumsy hand movements and tripping when walking over uneven ground or when trying to walk fast or break into a run - long before he has detectable muscle weakness on motor strength testing (loss of dexterity and "fatigueability" of movement precedes motor weakness); and physical examination may reveal spasticity chiefly affecting the flexors of the upper limbs and extensors of the lower limbs long before any overt weakness is apparent

- test for spasticity by asking the patient to play a piano in mid-air with the arms extended and observe the fluidity of his finger movements; and ask the patient to wiggle his toes fast and smoothly => clumsiness of movements suggests UMN pathology

- increased muscle tone in the upper limb can be tested by holding the patient's hand as if shaking hands, and then gently flexing and extending the elbows and wrists and then rotating the elbows by supinating-pronating the forearm => a slight "catch" may be the earliest sign of increased muscle tone

- increased muscle tone in the lower limb can be tested by gently rolling the leg from side-to-side with your hand under the knee, and when the leg is rolling freely, quickly flick the knee up in the air => the normal leg will passively flex at the knee, while the spastic leg will remain stiff and jerk up in the air

- acute pathology affecting the corticospinal tract may produce weakness, flaccidity, hyporeflexia and an absent Babinski response mimicing a LMN lesion => it may not be easy to differentiate between a cauda equina lesion and a lower spinal cord lesion if the pathology is acute eg. spinal infarction, extradural hematoma or spinal hemorrhage (hematomyelia), acute lumbar disc herniation, acute spinal trauma

- the acute hyporeflexia associated with spinal shock may take weeks to recover, and overt clinical evidence of UMN pathology (hyperreflexia and spasticity) may be delayed

- a clue that any muscle weakness is due to an UMN lesion is that UMN weakness mainly affects generalised movements rather than particular muscles, and UMN weakness mainly affects the extensor groups of the arms (shoulder abductors, elbow extensors, wrist extensors) and flexor groups of the legs (hip flexors, knee flexors and foot dorsiflexors)

(* the anti-gravity muscles are relatively preserved - biceps of the upper limbs and quadriceps of the lower limbs)

- myelopathies affecting the cervical anterior horn cells (amyotrophic lateral sclerosis, syringomyelia, intramedullary tumors) => weakness + muscle atrophy + fasiculations of the upper limbs (especially intrinsic hand muscles) + hyperreflexia of the lower limbs (due to corticospinal tract involvement)
 

Clinical clues suggesting motor deficits secondary to chronic spinal cord disease

spasticity precedes weakness spasticity is associated with increased muscle tone and hyperreflexia and clonus and a positive Babinski (extensor plantar response) weakness mainly involves generalized movements rather than a particular muscle group weakness mainly affects the extensor groups of the arms and flexor groups of the legs => the patient appears "stiff" with flexed arms and extended legs loss of independent fine finger motor movements => clumsiness of finger movements

Radicular symptoms

- produced at the level of the lesion if the lesion affects the nerve roots

- they are of precise localising value if present

- may produce unilateral or bilateral symptoms

- sensory symptoms may vary widely - from severe knife-like pains, icy-cold bandage-wrap sensations to vague warm glowing sensations - and they usually extend from the back along a dermatomal pattern

- bilateral T3/T4 dermatomal pain may mimic a heart attack or heartburn

Anterior cord syndrome

• characterised by a loss of motor function and pain-temperature sensation below the level of the lesion + preserved posterior column function (position sense and vibration sense)
• typically seen following hyperflexion injuries with impingement of bone or herniated disc tissue directly on the anterior spinal cord, or due to mechanical compression of the anterior spinal artery and secondary infarction of the anterior spinal cord, or rarely due to aortic dissection interrupting the blood supply to the anterior spinal arteries

Central cord syndrome

• most commonly associated with hyperextension injuries in elderly patients with cervical spondylosis and a narrow cervical canal => buckling of the ligamentum flavum => pincer-mechanism cord compression against vertebral body osteophytes in a narrow cervical canal => greatest compressive effects on the central mass of the cord substance => bilateral arm weakness >> lower limb weakness with paresis more dense distally than proximally +/- variable sensory impairment (pain and temperature sensory loss >> propioceptive sensory loss) and bladder dysfunction (* mnemonic MUD = motor > sensory, upper > lower, and distal > proximal)
• the degree and location of the neurological deficits depends on the exact location and size of the lesion
• bilateral "burning hands" paresthesias may be an early symptom and may precede any neurological signs, or may occur in isolation without any neurological deficits
• this syndrome may also be chronic and slowly progressive in its time-course - seen in chronic cervical spondylosis compressing the spinal cord, and in syringomyelia, and in tumors of the central spinal cord (see the appendix for a graphic presentation of evolution of chronic central cord syndrome)

Posterior cord syndrome

• characterized by proprioceptive sensory loss + preservation of pain and temperature sensory function + preservation of motor function
• usually due to posterior spinal artery occlusion, chronic atherosclerosis and impaired collateral circulation, tumors or discs compressing the posterior spinal cord, or vitamin B12 deficiency

Brown-Sequard syndrome

• lateral cord syndrome due to a lesion involving half of the spinal cord
• ipsilateral loss of motor function and proprioceptive sensory function + contralateral loss of pain-temperature sensation
• most commonly due to traumatic hemisection of the spinal cord (eg. stabbing knife thrust); rarely due to radiation injury or air embolism associated with scuba diving; can also occur secondary to spinal tumors or other local pathology compressing the lateral spinal cord
• partial Brown-Sequard syndromes are more common => varying degrees of paresis and analgesia

Inferior cord syndrome (conus medullaris) syndrome

• involvement of the terminal spinal cord
• usually of rapid onset
• more severe back pain, less severe radicular symptoms
• symmetrical defects
• weakness sacral
• saddle distribution sensory loss +/- sensory dissociation
• tendon reflex loss - ankle > knee
• early consistent impotence +/- bladder involvement
• subacute lesions may produce UMN signs - hyperreflexia of ankle jerks, increased anal tone and spastic bladder
• see emedicine.com's cauda equina syndrome chapter for further details

Cauda equina syndrome

• slow progressive loss; often asymmetric or unilateral
• often due to chronic disc herniation +/- spinal stenosis
• may be due to spinal tumors
• less severe back pain, may produce severe radicular symptoms
• sensory loss affects all sensory modalities - lumbar > sacral
• sensory loss may affect penis/clitoris and pubic area, and be asymmetrical
• sensory loss may follow a specific dermatomal pattern
• muscle weakness - lumbar > sacral
• muscle weakness mainly affects glutei, hamstrings, gastrocnemius and soleus muscles
• muscle atrophy and fasiculations common
• tendon reflex loss - knee > ankle
• bladder involvement late (flaccid bladder)
• see emedicine.com's cauda equina syndrome chapter for further details

Syringomyelia

• the result of central cord cavitation affecting a few segments, and usually involving the cervical spinal cord
• frequently found in Arnold-Chiari malformations affecting the upper cervical cord and medulla
• mainly affects the crossing fibres of the spinothalamic tract as they decussate in the ventral white commissure => bilateral pain-temperature sensory loss over a few segments eg. only affecting the neck and upper shoulders in a cape-like distribution (or only affecting the upper limbs) with normal sensation above and below the affected dermatomes
• does not affect the spinothalamic tracts in the early stages => no initial lower trunk or lower limb pain-temperature sensory loss
• does not usually affect the dorsal columns => normal position sense ("dissociative" sensory loss)
• may rarely affect the lower motor neurons to the upper limbs early in the disease course, and may eventually affect the corticospinal tracts
• may affect the spinal extension of the trigeminal nucleus => face hypoesthesia in a characteristic balaclava helmut distribution

Clinical clues and clinical spinal cord syndromes

- it is important to keep some general principles in mind when attempting to diagnose a spinal cord syndrome

Patients often have sensory symptoms in the absence of detectable sensory deficits, whereas detectable motor signs may be found in the absence of motor symptoms

Acute motor signs may consist of weakness and hyporeflexia (due to spinal shock), while chronic motor signs are more likely to consist of spasticity and hyperreflexia

Because motor weakness due to corticospinal tract involvement affects generalised movements, it may not be possible to definitively determine a spinal cord level based on the motor examination => a sensory examination showing a discrete sensory dermatomal deficit level may better determine that a sensorimotor deficit is due to spinal cord disease (rather than due to a radiculopathy or a peripheral neuropathy)

The presence of back pain + spinal percussion tenderness in the presence of a new neurological deficit strongly suggests spinal cord disease

- local pain over the spine developing over minutes-hours +/- neuro deficits => spinal hemorrhage, spinal infarction, vertebral fracture, acute disc herniation

- local pain over the spine developing over hours-days +/- neuro deficits => epidural abscess or epidural hematoma or transverse myelitis

- local pain over the spine developing over months +/- neuro deficits => spondylosis or infection or tumors

- radicular pain due to spinal disease is rarely seen without local spinal pain and radicular pain does not radiate to the terminal sensory distribution of the involved nerve (although associated paresthesias may extend to the terminal nerve ends)

- Lhermitte's sign = Electric-shock sensations lasting seconds and extending from the neck down the back +/- radiation to the limbs, and which usually occur when the neck is flexed - is most commonly seen in multiple sclerosis, but is also seen in other lesions affecting the posterior cervical spinal cord eg. cervical spondylosis compressing the posterior spinal cord

- hyporeflexia could be due to nerve root pathology (eg cauda equina syndrome), but is also seen temporarily in acute spinal cord pathology (spinal shock - trauma, infarction, hemorrhage, disc herniation or transverse myelitis)

- hyperreflexia is eventually seen in all spinal cord syndromes and finding a reflex level is of localising importance

• hyperreflexia of the lower limbs + normoreflexia of the upper limbs => lesion of the thoracic or lumbar cord
• hyperreflexia of the lower limbs and finger flexors + normal biceps reflex => lower cervical cord lesion
• hyperreflexia of the lower limbs + hyporeflexia of the upper limbs => cervical spondylitic myelopathy + radiculopathy, or cervical central cord pathology involving the LMNs to the upper limbs
• hyperreflexia of the upper and lower limbs + normal jaw jerk => upper cervical cord lesion

- an extensor plantar response (Babinski sign present) is often seen in early spinal cord disease, but it is occasionally absent even in advanced disease

- bladder dysfunction is not an early symptom of spinal cord disease; lesions of the cauda equina or acute/subacute myelopathies (spinal shock) => flaccid bladder with urinary retention and overflow incontinence; while more slowly progressive myelopathies => spastic bladder with urgency, frequency and incontinence

The combination of spasticity + poor coordination + incontinence => spinal cord disease until proved otherwise (also consider frontal lobe disease and normal pressure hydrocephalus)

- early cervical central cord syndrome will be missed if a careful pain-temperature sensory examination of the neck, shoulder area, upper trunk and upper extremities is not performed - because an isolated band of pain-temperature hypoesthesia may be the sole abnormal finding in early disease

An acute myelopathy can be due to a transverse myelitis, but this is a diagnosis of exclusion - first exclude acute compressive myelopathies by immediate neuroimaging

Differential diagnosis of spinal cord syndromes

Local pain + quadriplegia/paraplegia + non-selective sensory loss + loss of bladder function

• acute (minutes) => spinal cord infarction (often spares the dorsal columns), spinal cord trauma, spinal hemorrhage, acute disc herniation
• subacute (hours, days, weeks) => transverse myelitis, spinal epidural abscess, spinal epidural tumor

Chronic spastic quadriplegia/paraplegia + spastic gait ataxia (evolving over months-years)

• disorders with no sensory abnormalities => amyotrophic lateral sclerosis, myelopathy of cervical spondylosis, familial spastic paraplegia
• disorders with loss of proprioception => arachnoiditis, spinal multiple sclerosis, myelopathy of cervical spondylosis, arteriovenous malformation, subacute combined degeneration of the spinal cord, AIDS myelopathy, spinocerebellar degeneration, spinal tumors, tabes dorsalis
• disorders with loss of pain-temperature sensation => spinal tumors, myelopathy of cervical spondylosis, radiation myelopathy

Chronic atrophic paralysis of the hands (evolving over months-years)

• disorders with segmental sensory loss involving pain-temperature only or all sensory modalities => syringomyelia, spinal tumors, spinal cord injury
• disorders without sensory loss => amyotrophic lateral sclerosis, cervical spondylosis, extrinsic tumors of the upper cervical cord

Chronic paraplegia + low back pain + areflexia + loss of bladder function (Cauda equina syndrome)

• herniated disc, spinal stenosis, tumors of the cauda equina, arachnoiditis

Rapidly evolving areflexic quadriparesis/paraparesis in the absence of trauma or spinal compression

• acute transverse myelitis (back pain + sensory deficit/level + normal reflexes above the lesion + bladder dysfunction)

Differential diagnosis

• Guillane-Barre syndrome => rapidly evolving areflexic quadriparesis/paraparesis (no back pain + no sensory deficits + diffuse areflexia + normal bladder dysfunction +/- cranial nerve dysfunction)
• bilateral anterior cerebral artery occlusion => acute paraplegia + urinary incontinence + hyperreflexia +/- gait apraxia +/- dementia +/- sensory loss (sensory loss in cortical infarction only involves position sense and spares pain-temperature = exact opposite of spinal infarction)
• normal pressure hydrocephalus => gait ataxia +/- bilateral limb weakness + urinary incontinence + no spasticity or sensory deficits

For further information on many diseases causing spinal cord syndromes, consult this excellent online website

http://www.neuro.wustl.edu/neuromuscular/spinal.html
 

Appendix

Motor testing

- there is no "pure" single nerve testing of the upper and lower limbs

- some easy-to-remember combinations include:-

• shoulder abduction - C5
• elbow flexion - C 5,6
• elbow extension - C7
• wrist and finger extension - C7
• finger flexion - C8
• finger abduction - C8, T1
• thumb adduction and opponens - T1
• hip flexion - L 2, 3, 4
• knee extension - L 3, 4
• foot dorsiflexion - L 4, 5
• 2nd - 5th toe dorsiflexion - L 5
• 1st toe dorsiflexion - L 5 or S1
• foot plantar flexion - S1
• squeezing buttocks together (gluteus maximus) - S1
• anal sphincter "tightening" - S2, 3, 4

- the biceps reflex is C5/6, triceps reflex is C7/8, knee reflex is L3/4 and the ankle reflex is S1

(* although many textbooks/journal articles suggest that first toe dorsiflexion innervation is primarily from L5, other textbooks/journal articles suggest S1 as the major innervation=> because of this discrepancy in opinions, it is recommended that you use foot and small toe(s) dorsiflexion for L5 testing and plantar flexion of the foot for S1 testing)

Grading of motor strength

• 5+ = Normal
• 4+ = Slightly less than full power against resistance
• 4 = Able to overcome moderate resistance
• 4 - = Able to overcome mild resistance
• 3 = Able to accomplish full ROM against gravity
• 2 = Able to accomplish full ROM with gravity eliminated
• 1 = Only trace muscle contraction, may only be palpable
• 0 = Flaccid

Sensory dermatomes

Somatotopic anatomy of the spinal cord

Summary of the clinical features of some spinal cord syndromes
 
 

	Pain	Percussion tenderness	Acute progression	Chronic progression	Fever	Flaccidity	Spasticity	Reflexes	Sensory deficit
Epidural hematoma	+++	++	+++	+	-	+++	-	+	++
Epidural abscess	++++	+++	++	++	+++	+++ (acute)	++ (chronic)	+	++
Primary neoplasm	+	+	-	+++	-	+	+++	+++	+
Secondary metastasis	+++	+++	+	++	-	++	++	+	+
Trauma	+++	+++	+++	-	-	+++	-	-	++
Cervical spondylosis	+/-	+/-	-	+++	-	-	+++	+++	+
Transverse myelitis	+/-	-	+++	-	+/-	++	late	+/-	+++

(* see the low back pain guidemap for more information on the diagnostic workup of some spinal cord syndromes)

Evolution of chronic central cord syndrome

Disclaimer: My EM guidemaps reflect my personal approach to problem-solving/managing clinical cases in an ED setting and they should not be regarded as the standard of care. They merely represent the personal opinions of the author and they should only be used in clinical practice if the reader-user has substantial reason to believe that the clinical advice contained in the guidemaps is valid and accurate. The guidemaps are not meant to be "authoritative" and the reader-user should consult standard medical textbooks and expert opinion articles/guidelines for more authoritative advice. The reader-user should particularly confirm all drug doses, their indications and contra-indications, prior to their use.