Disorders of the Spinal Cord
doc. MUDr. Valja Kellerová, DrSc.
Department of Neurology
Anatomical and physiological notes
• spinal segment
• is a part of the spinal cord, having one ventral and one dorsal root
• the ventral and the dorsal roots join together and form the spinal nerve
• spinal nerves get out of the spinal canal through the intervertebral foramina
• the segmental level:
• lower motor neuron cell bodies are located in the anterior horns (grey matter), for each
segment, their axons form an anterior spinal root, and project to groups of muscles (the
myotome)
• sensory neurons in a dorsal root enter the spinal cord (the territory of skin innervated by
a segment = a dermatome)
• the monosynaptic stretch reflex arc functions at segmental level
• important long tracts:
• lateral corticospinal (pyramidal) tract (axons from neurons in the motor cortex that
project to motor neurons at the segmental levels)
• spinothalamic tract (sensory fibres subserving pain and temperature enter at each
segment, synapse, and the second order neuron crosses to join the spinothalamic tract)
• posterior (dorsal) column tract (sensory fibres subserving position, vibration and
discriminative touch enter and directly join the posterior, dorsal columns)
• spinocerebellar tract (sensory fibres transmitting unconscious proprioception connect
with cells of the posterior horn – posterior grey column, the second order neurons ascend
via the the spinocerebellar tracts)
• long tracts for autonomic function (autonomic fibres descend and synapse with the cell
bodies in the intermediolateral horns – grey columns, sympathetic fibres exit between T1
and L2, and parasympathetic between S2 and S4)
• anatomical relationships of spinal segments and bony spine:
• the end of the spinal cord is under which vertebra (vertebral body)? (L2)
• spinous processes – spinal segments
• upper C
correspond
• lower C
segment + 1
• upper T
segment + 2
• lower T
segment + 3
• T 10
segment L 1
• T 12
segments L 4-5
• L1
segments S 1 – 5, Co
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Features of a spinal cord lesion:
•
motor disorders, paresis or plegia: ipsilateral
• central (the upper motor neuron lesion) – in the lateral column lesions
(with severe spastic hypertonia, hyperreflexia, clonus, pathologic pyramidal signs)
•
peripheral (the lower motor neuron lesion) – in the anterior horn lesions
(without sensory loss)
•
mixed – in cases of both motor neuron lesions, upper and lower
(central and peripheral signs are combined) - in motor neuron disease
Motor neuron disease - Amyotrophic lateral sclerosis:
• clinical signs:
muscle atrophies, fasciculations (peripheral)
hyperreflexia, pyramidal signs (central)
• selective degeneration of the motor neurons:
• central in the crebral cortex
• peripheral in the anterior horns of the spinal cord and in the motor
cranial nerve nuclei in the medulla oblongata
•
sensory funtion impairment:
• segmental or dorsal root affection (dermatomal distribution in area radicularis)
• spinal cord disorders in columns (in the white matter), column lesions
•
•
central cord
(posterior column lesion – loss of deep sensation)
lesion (lesions in the central grey matter) - spinothalamic tract damage –
loss of pain and temperature sensation
autonomic nervous system disorders
• sfincter disorders: disorder of urination, bowel function and sexual function
• vasomotor and trophic disorders
•
cranial nerves intact
Localisation of the lesion site Vertical localisation:
•
Upper cervical spinal cord lesion – segments C1 – C4 manifests by:
• hemi- or quadriparesis (quadraparesis, tetraplegia)…central
• sensory loss up to the level of the lesion
• radicular irritation – neck pain
• paresis of the diaphragma (n. frenicus - C4)
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•
Cervical enlargement, intumescentio cervicalis – segments C5 – 8:
• arm: lower motor neuron lesion (peripheral) at the level of segmental
cord damage (and upper motor neuron lesion below the lesion)
•
•
•
leg: upper motor neuron lesion (central)
radicular irritation – shoulder girdle pain
sensory loss
•
Thoracic spine lesion – segments T1 – T12:
• mono- or paraparesis of the legs…central
• arms: normal
• sensory loss
• urinary retention
•
Lumbosacral spine lesion, lumbar enlargement, intumescentio
lumbalis – segments L2 – S2:
• mono- or paraparesis of the legs…peripheral at the level of segmental cord
damage (and upper motor neuron lesion below the lesion, detecting level of cord damage)
•
The upper part – lumbar segments L1 – L4:
• paresis of the thigh muscles
weakness of flexors and adductors of the thigh and of extensors of the shin (crus)
•
•
•
•
•
deep tendon reflexes L2-4 are absent
sensory loss in areae radiculares
urinary incontinence (sympathetic lesion)
cremasteric reflex is absent in L1-2 segmental lesion
The lower part – epiconus – L5 – S2 segmental lesion:
• paresis resembles radicular lesions L5 + S1 – mistakes!
weakness of extensors predominates – peroneal muscles, gluteal
muscles, flexors of the crus
•
•
•
•
deep tendon reflexes L2 – S2 are absent
sensory impairment (on the dorsal part of the leg and from the knee distally)
automatic bladder (reflex neurogenic bladder)
sexual dysfunction
investigation – MRI must be focused to the T12-L1 vertebra level!
•
• cord compression is not caused by disc prolapse, but often by a tumour!
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•
Conus lesion – segments S3 – S5
• paraparesis…is not present!
• sensory disturbance – saddle anesthesia over the “saddle area”
• pain over the “saddle area”
• sphincteric paralysis:
• disturbance of urination (denervated autonomous bladder – retention)
• faecal incontinence
• sexual dysfunction - impotence
• investigation – MRI at
• cause: tumour, trauma…
•
the level of the L1 vertebra
Cauda equina lesion – roots L3 – S5
• paresis – peripheral, asymmetrical (with reflex loss, usually foot drop…)
• sensory loss
• radicular areas – hypesthesia
• over the sacral area (perianal, perigenital, may be hemi-)
•
•
radicular leg pain
sphincter disorders
• acute retention of urine
• constipation
•
•
•
investigation - below the vertebral body of L2
cause: lumbar disc prolapse! (L4/5, L5/S1…) is the most frequent cause
management: the patient has to be operated and disc prolapse
removed during 24 hours!
Horizontal localisation:
Column lesions – signs:
– posterior column syndrome (tabic, or pseudotabic):
• loss of deep sensation:
vibration (pallhypesthesia, pallanesthesia), joint
position sense, discriminative sensation, paresthesias
•
•
•
spinal ataxia
absent tendon reflexes
worsening of balance with eyes closed !
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– lateral column syndrome (spastic):
• spastic paraparesis of the lower limbs
• cerebellar signs
– combined lesion
Column lesions – etiology:
• posterior column syndrome:
• tabes dorsalis
• diabetes mellitus
• subacute combined degeneration of the spinal cord
• lateral column syndrome:
• degenerative diseases: spastic spinal paraplegia
• combined lesion:
• subacute combined degeneration of the spinal cord
• degenerative diseases: spinocerebellar (Friedreich´s) ataxia
Subacute combined degeneration of the spinal cord:
• chronic degenerative changes in the posterior and lateral columns – myelin
degeneration, followed by axonal degeneration
• metabolic disorder – secondary to vitamin B 12 deficiency
• vitamin B12 (extrinsic factor) is absorbed only in the presence of an intrinsic factor produced
in the gastric mucosa and they form a hematopoietic factor
• a deficiency of vitamin B12 leads to: pernicious megaloblastic hyperchromic anemia
subacute combined degeneration in some cases
• causes of vitamin B 12 deficiency:
• abnormal absorption
– atrophy of the gastric mucous membrane
– gastric resection (for carcinoma) or subtotal gastrectomy for peptic ulcer
– disease of the small intestine
• inadequate intake – strict vegetarian diet may manifest after 2-3 years
• neurological signs (independent on anemia):
• paresthesias of the extremities
• spinal ataxia – an ataxic gait disturbance
- worsening of balance in darkness or with eyes closed
• loss of deep sensation (vibration sense, position sense)
• mental changes
• diagnosis: estimation of the vitamin B12 concentration in the serum before therapy,
hematologic examination…
• treatment: substitution of vitamin B12: start with 1000 micrograms daily for 2 weeks
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Central cord lesions – signs:
•
loss of pain and temperature sensation (involvement of grey matter around
the central canal – tr. spinothalamicus)
• the other
modalities of sensation are preserved – “dissociated sensory
loss”
Central cord lesions – etiology:
•
syringomyelia
intramedullary tumours (ependymoma, astrocytoma)
•
• hematomyelia…
Syringomyelia:
• development of a cavity (syrinx) within the spinal cord central area with ependymal
cells in the wall, later gliosis occurs
• sometimes in association with obstruction around the foramen magnum
– in conjunction with the Arnold-Chiari malformation (cerebellar ectopia below the
level of the foramen magnum)
• hydromyelia is the congenital persistence and widening of the central canal
• localisation:
• lower cervical and upper thoracic segments
• lower brain stem – medulla oblongata (syringobulbia)
•
signs:
• loss of pain and temperature sensation in a cape-like distribution
• painless burns, injuries, chilblains, infection…
• disturbances of autonomic and trophic function (damage to the intermediolateral
ttract) – puffy swelling of the hands, “succulent” hand, skin atrophy on the palm…
• wasting and weakness of the small muscles of the hand – from anterior horn cell
involvement (pressure of the cavity)
• long tract signs follow later (spastic paraparesis of the lower extremities)
• clinical course: mostly slowly progressive or stationary
•
•
investigations: MRI
treatment:
• X-irradiation in some cases
• neurosurgical treatment (in progressive deterioration – cystic cavity extends):
• decompression (in Arnold-Chiari malformation)
• syringostomy – the syrinx (cavity) is drained into the CSF space or a
syringoperitoneal shunt is performed
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Brown–Séquard´s syndrome:
a lesion is limited to one-half of the spinal cord, “hemisection”
signs:
• central paresis….ipsilateral
• loss of deep sensation…. ipsilateral (below the lesion)
• loss of pain and temperature sensation….contralateral (below the lesion)
• segmental damage
• lower motor neuron lesion in the myotome (groups of muscles supplied by the involved
segment)
• loss of all sensations at one dermatome level
Brown–Séquard´s syndrome - etiology:
•
•
trauma (stab or bullet wounds…)
tumour
Complete transversal lesion – signs:
– plegia of extremities (no sign of motor function)
– anesthesia involves all modalities, occurs up to the level of the lesion
– sfincter disorders: retention, obstipation, disorder of sexual function.
Increase in the intravesical pressure overcomes internal sfincter integrity and results in
“dribbling overflow incontinence” (ischiuria paradoxa). After some days or
weeks a reflex bladder develops with automatic emptying.
A mass reflex may develop, icluding urination and defecation at the same time,
complete emptying (a spinal cord automatism).
– spinal cord automatism – fenomenon of flexion in three joints on the lower
limb: in the hip, knee and ankle, in response to painful stimulus applied on the dorsum of
the tarsus.
– rapidly progressive lesions produce “spinal shock” – the limbs are flaccid,
reflexes and pyramidal signs are absent. This upper motor neuron lesion looks like
lower motor neuron lesion - “pseudo-flaccid paralysis”. After several days or weeks
the muscle tone returns, spasticity develops, and the signs of the upper motor neuron lesion
occur.
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Clinical diagnostics of the spinal cord lesions– etiology
•
diffuse and multiple neurological processes:
•
•
•
•
•
inflammatory
degenerative
metabolic
multiple sclerosis…
localised disorders
• compression of the spinal cord – by expanding processes: slowly progressive
• extramedullary lesion
• extradural (metastasis, myeloma, lymphoma…)
• intradural (meningioma, Schwannoma)
• intramedullary lesion (astrocytoma, ependymoma, syringomyelia...)
• trauma – rapidly progressive cord lesion
•
•
vascular disorders of the spinal cord
disc disease and spondylosis
Manifestations depend on the site:
•
extramedullary lesion produces signs of:
• root damage (motor and sensory impairment)
• segmental damage:
• segmental signs
• motor: lower motor neuron weakness and atrophy in a myotomal pattern
• sensory: sensory loss in a dermatomal distribution
with central cord lesions: pain and temperature sensations are impaired
• loss of tendon reflexes at the level of the lesion
• long tract signs
• motor: upper motor neuron weakness below the level of the damage
• sensory: sensory deficit up to the level of the lesion
• autonomic (bladder symptoms…)
•
intramedullary lesion produces segmental damage only,
not the root damage
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