10.10 Spinal Cord Disorders Flashcards
How does the level of the lesion and the sensory level found on examination correspond?
The level of the lesion and the sensory level found on examination do not necessarily correspond.The sensory level is often lower, and in the chronic phase of incomplete lesions, may regress.
With acute severe lesions where will the clinically detectable sensory level be?
Close to the lesion
With chronic milder lesions where will the clinically detectable sensory level be?
At level often far away from lesion
What does the interruption of the ascending sensory pathways produce?
Sensory loss
What does interruption of the descending motor pathways produce?
Upper motor neuron syndrome
What does the UMN bladder cause?
Upper motor neuron bladder
Small volume:
- frequency
- urgency
- urge incontinence
What does a LMN bladder cause?
Lower motor neuron bladder
Large Volume:
- Difficulty intitiating flow
- overflow
- incontinence
What does the interruption of the descending autonomic pathways causes?
Bladder and bowel dysfunction
What pathways are affected when the anterior spinal artery is clamped?
- corticospinal
- spinothalamic
What will develop with an acute and chronic insult to the UMN?
Acute - spinal shock (floppy weakness)
Chronic - UMN syndrome
Define spinal shock
- Severe cord injury causes spinal shock in the acute phase
- Motor -ABSENT reflexes, and 0-1/5 power
- Sensory- Sensory level close to the level of the lesion
- Autonomic dysfunction - Acute urinary retention
Clinical manifestations of Chronic UMN syndrome
Motor
- ⬆️reflexes, clonus, and power lost in UMN pattern
- Other reflexes: Babinski, flexor spasms, extensor spasms
- Spasticity (velocity-dependent, clasp-knife increase in tone)
- The limbs may be held in extension or flexion posturing depending on the dominant pattern of spasticity
- No or mild atrophy (disuse)
Sensory
- Sensory level, not always clear
Autonomic dysfunction
- Spastic UMN bladder (small volume + urgency)
Spasms
- In paraplegic patients, spasticity and hyperreflexia are often accompanied by increased cutaneomuscular reflex excitability, through polysynaptic propriospinal pathways
- Pulling a on a pair of trousers may be enough to produce spasms of the hip and knee flexors, sometimes accompanied by autonomic effects (sweating, hypertension, emptying of the bladder)
- Loss of tonic supraspinal input from the corticospinal and reticulospinal tracts account for this phenomena
Transverse myelopathy
- Interruption of the ascending sensory tracts → combined sensory loss
- Interruption of the descending motor tracts → paraparesis, the UMN syndrome
- Interruption of the descending autonomic tracts → bowel and bladder dysfunction
- It is more typical for the section to be incomplete and irregular, and the clinical findings reflect the extent of damage
Anterior cord syndrome
- Interruption of the spinothalamic tract → Sensory level to pinprick
- Posterior part of spinal cord intact → sparing of JPS (joint position sense)
- Example: spinal cord infarct with anterior spinal artery
- Ischemic injury to the spinal cord affects areas with high metabolic demand, such as the anterior horn cells and grey matter, before leading to complete cord necrosis
- most common cord clinical presentation of myelopathy
Central cord syndrome
Pathogenesis
Causes
- Spinal cord injury starts centrally
- Loss of pain and temperature in a cape- like distribution, sparing of JPS
- Involvement of corticospinal tracts cause paraparesis and UMN syndrome
- Damage to anterior horn cells → Atrophy over several segments
- Damage to the autonomic pathways at C8-T2 → Horner syndrome
- Lateral extension leads to interruption of the descending motor pathways → UMN signs
Causes
Cervical spondylosis (hyperextension injury), syringomyelia, intramedullary spinal cord tumours, spinal cord haemorrhage
