CPEO

Question 1

CPEO Definiton

Answer 1

A muscle disorder associated with defects in mitochondrial function, characterized by progressive external ophthalmoplegia.
Variety of clinical presentations, progressive ophthalmoplegia, sometimes pigmentary retinopathy.
Some patients with the typical mitochondrial changes found on muscle biopsy had primary neurological signs such as ataxia and seizures.

Question 2

CPEO aeitiology

Answer 2

Nearly all cases are maternally transmitted due to mitochondrial DNA inheritance.

Question 3

CPEO features eyes

Answer 3

Progressive symmetrical loss of ocular motility with ptosis and orbicularis weakness (sometimes no ptosis).
Usually upgaze is the first to be affected
Smooth muscle function, including pupillary reactions and accommodation, remains normal.
In late stages, eyes become virtually immobile due to secondary fibrotic changes, which may be identified by forced duction testing.
Symmetrical involvement of both eyes leads to a lack of awareness of diplopia, but not all patients have equal restriction in early stages.
Saccadic velocities are always reduced.

Question 4

CPEO in kid syndrome is called…

Answer 4

Kearns Sayre Syndrome:

Occurs as a result of large-scale single deletions (or rearrangements) of mitochondrial DNA, which occur spontaneously
Characteristics include CPEO starting in childhood, fine pigmentary retinopathy, and heart conduction block.
Features must present before 20 years of age for diagnosis.

Question 5

other conditions associated with CPEO

Answer 5

Other associated conditions include ataxia, dementia, raised CSF protein, and short stature.

Question 6

Diff dx for CPEO

Answer 6

Myasthenia: Positive response to Tensilon, antiacetylcholine receptor antibodies, or normal saccadic velocities support the diagnosis.
Mechanical disorders such as Graves’ orbitopathy.
Supranuclear gaze palsy: Shows improvement in movement on doll’s head testing, while CPEO remains unchanged.
Multiple cranial nerve palsies: Asymmetrical eye movement similar to CPEO can occur with brainstem demyelination and Miller Fisher syndrome.

Question 7

mx for CPEO (non surgical)

Answer 7

Initial Assessment:

All patients should have an ECG and fundus examination to identify those with Kearns Sayre syndrome.
Repeat ECG yearly for those without evidence of heart conduction defects.

Monitoring:

Recording progress with fields of uniocular fixation is useful as the Hess chart may not be a reliable indicator due to BIL nature of condition.
Prisms may relieve diplopia in the early stages. The eyes are relatively immobile in the later stages and prisms are then of little benefit

Question 8

sx for CPEO

Answer 8

Surgical Options:

Muscle surgery may be justified to straighten the eye if anchored in a grossly eccentric position, with risks of recurrence as the disease progresses.
Local anesthesia is preferred due to potential anaesthetic risks from heart block or pharyngeal muscle weakness.
Surgery is not usually required; ptosis props may assist with ptosis.
Caution:
Ptosis surgery carries risks of exposure keratitis due to poor orbicularis function and absent Bell’s phenomenon.