Syringomyelia

Published on 02/04/2015 by admin

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Last modified 02/04/2015

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71 Syringomyelia

Instruction

Examine this patient’s arms.

Salient features

History

• Classically patient has a history of painless trauma or burns with cigarettes, hot water

• Patient may have cuts that never seem to hurt

• Patient may have a long history of poorly localized unpleasant pain (although pain sensation is impaired these patients have severe pain)

• Patient may notice scoliosis during childhood.

Examination

• Wasting and weakness of the small muscles of the hands and forearm (if fasciculation is seen, then the other diagnosis that comes to mind at this stage is motor neuron disease (Case 69))

• Rarely patients may have hypertrophy in limbs, hand and feet (Lancet 1996;347:1593–5)

• Tone and deep tendon reflexes are diminished

• Loss of pain and temperature sensation with intact vibration, light touch and joint position sense: this deficit is the underlying cause for any burns present

• There may be Charcot’s joints of the shoulder and elbow

• There may be signs of hemi-hypertrophy of the limbs.

Proceed as follows:

• Examine vibration sense over the fingers, lower end of radius, elbow and clavicles (note that vibration sense is impaired only at a later stage)

• Look for Horner syndrome

• Examine the neck posteriorly for scar of previous surgery

• Ask whether you may examine the following:

• The lower limbs for pyramidal signs
• The face for loss of temperature and pain sensation (starting from the outer part of the face and progressing forward, looking for the ‘onion-skin pattern’ of sensory loss caused by a lesion in the spinal nucleus of the fifth cranial nerve, which extends from the pons down to the upper cervical cord)
• For lower cranial nerve palsy
• For nystagmus and ataxia (caused by involvement of the medial longitudinal bundle from C5 upwards)
• For kyphoscoliosis (caused by paravertebral muscle involvement).

Diagnosis

This patient has dissociated sensory loss (lesion) caused by syringomyelia (aetiology) and has had severe painless trauma or burns (functional status).

Questions

How common is syringomyelia?

It is a rare disorder affecting both sexes equally; the usual age of onset is the fourth or fifth decade.

How do you explain the clinical features?

• At the level of the syrinx:

• Anterior horn cell involvement causing a lower motor neuron lesion
• Involvement of the central decussating fibres of the spinothalamic tract producing dissociated sensory loss and late development of neuropathic arthropathy and other trophic changes.

• Below the level of the syrinx:

• Involvement of pyramidal corticospinal tracts resulting in spastic paraparesis (sphincter function is usually well preserved)
• Involvement of cervical sympathetics:
• Horner syndrome (miosis, enophthalmos, ptosis).

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