intrinsic cord lesion

Question 1

definition of syrinx, syringomyelia, syringobulbia

Answer 1

• Syrinx: tubular cavity in central canal of the cervical cord
• Symptoms may be static for yrs but then worsen fast
• e.g. on coughing, sneezing as ↑ pressure → extension
• Commonly located in cervical cord
• Syrinx expands ventrally affecting:
• Decussating spinothalamic neurones
• Anterior horn cells
• Corticospinal tracts

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Signs of intrinsic cord lesion usually caused by MS. Much rarer causes include intrinsic tumour or a syrinx (syringomyelia).

Syringiomyelia (relatively common) – fluid filled cavity (syrinx) within spinal cord.

Syringobulbia (v.rare) - caused by fluid filled cavity (Syrinx) within brainstem.

Question 2

epidemiology

Answer 2

• Mean age of onset: @ 30yrs

- Incidence: 8/100000/yr

Question 3

s/s

Answer 3

• Cardinal Signs:*
• dissociated sensory loss
• absent pain and temp sensation with preserved light touch, vibration and join position sense. (due to pressure from syrinx on decussating anterolateral pathway in a root distribution reflecting location of syrinx e.g. for typical cervical syrinx sensory loss is over trunk and arms)
• wasting/ weakness of hands +/- claw hand (then arms, shoulders, resp muscles).
• Other signs*:
• Horners syndrome
• UMN leg signs
• Body asymmetry
• Limb hemi-hypertrophy or unilateral odo- or chiromegaly (enlarged hand or foot)

SYRINGOBULBIA (brainstem involvement):

• Nystagmus
• Tongue atrophy
• Dysphagia
• Pharyngeal/ palatal weakness
• 5^th nerve sensory loss

Charcot’s (neuropathic) joints:

• Increased range of movement (from lost joint proprioception)
• Destroys joint – which becomes swollen and mobile
• CAUSES: tabes dorsalis (e.g. knee), diabetic neuropathy, paraplegia (e.g. hips), syringomyelia (shoulder, wrist), leprosy, spinal osteolysis/cord atrophy)

Question 4

ix

Answer 4

mri spine

How big is the syrinx? Any base of brain (chiairi) malformation?

Question 5

mx

Answer 5

don’t wait for gross deterioration to occur

decompression at foramen magnum may be tried in chiari malformation to promote free flow of CSF and so prevent syrinx dilatation. Surgery may relieve pain and slow progression.