Syringomyelia and syringobulbia - Disorders of the spinal cord

Syringomyelia and syringobulbia

Definition

A syrinx is a fluid filled slit like cavity developing in the spinal cord (syringomyelia) or the brain stem (syringobulbia).

Age

Usually presents aged 20–40 years.

Sex

M = F

Aetiology

The cavity or syrinx is in continuity with the central canal of the spinal cord. It is associated with a history of birth injury, bony abnormalities at the foramen magnum, spina bifida, Arnold–Chiari malformation (herniation of the cerebellar tonsils and medulla through the foramen magnum) or hydrocephalus.

Pathophysiology

The expanding cavity may destroy spinothalamic neurones in the cervical cord, anterior horn cells and lateral corticospinal tracts.

Clinical features

Mixed upper and motor neurone signs, sometimes in an odd distribution, it is usually bilateral, but may affect one side more than the other.

·        Syringomyelia: There is typically wasting of the intrinsic muscles of the hand, with loss of upper limb reflexes and spastic weakness in the legs. The sensory changes are loss of pain and temperature sensation in the affected levels, e.g. C5 to T1 with preservation of touch. Neuropathic joints, neuropathic ulcers and accidental trauma and burns may result.

·        Syringobulbia: When the cavity extends into the brain stem the lower cranial nerves are affected – the tongue is atrophied and fasciculates, there may be nystagmus, dysarthria, Horner’s syndrome. Involvement of the fifth nerve nuclei causes loss of facial sensation, classically in a circumferential pattern, and the VIIIth nerve nucleus may be affected causing hearing loss.

Investigations

Diagnosed by CT or MRI scanning.

Management

Decompression of the foramen magnum, aspiration of the syrinx, sometimes with placement of a shunt may halt progression.

Prognosis

Condition is intermittently progressive over a number of decades.