Pupillary dilatation in head injury

1. Pupillary dilatation in
head injury-
The significance and
prognosis
Tom BK Feb 2015

2. Causes
• Ophthalmic
o Traumatic mydriasis -
• Transient – paralysis of muscle- self resolves. (also miosis from spasm)
• Permanent- torn pupillae sphinctae muscle centrally (or iridodialysis)
o ?Other ocular injury- Need good eye examination
o Typically otherwise neurologically normal, but can occur with or without
intracranial injury!

4. Causes
• Intracranial
o Transtentorial herniation – ipsilateral/ bliateral CN 3 (PNS) compression by
temporal lobe
• ‘Down and out’ eye- preserved lateral rectus and sup oblique
• Controlateral homonymous hemianopia from post cerebellar a
compression/ cortical blindness
• ‘Kernohan’s notch’ – compression of controlateral cerebral crus
(containing corticospinal and corticobulbar tracts) causing
hemiparesis on side of primary lesion- ‘false localising’
o Central herniation – Diencephalon and bilateral temporal lobe pushed
down
• Bilateral small/ large pupils
• Duret haemorrhage- pontine artery tear- bleeding in midbrain and
pons
• DI due to pituitary stalk compression

5. Herniation
1) Uncal (transtentorial)
2) Central
3) Cingulate (subfalcine)
4) Upward (transtentorial)
5) Tonsillar
Falx cerebri
Tentorium
cerebelli
Foramen
magnum

6. Causes
o Tonsillar herniation (‘coning’)
• Compression of lower brainstem and upper cord.
• Pressure on CV + resp centres- cardiorespiratory arrest – Bilateral
dilated pupils
o Reduced brainstem blood flow?
• Pupil effects not related directly to anatomical pathology- can have
pathology without mydriasis etc
• Ritter, A, Brain Stem Blood Flow, Pupillary Response, and Outcome in
Patients with Severe Head Injuries, Neurosurgery. 1999 May;44(5):941-8

7. Herniation
1) Uncal (transtentorial)
2) Central
3) Cingulate (subfalcine)
4) Upward (transtentorial)
5) Tonsillar
Falx cerebri
Tentorium
cerebelli
Foramen
magnum

8. Which is which?
• Neurology-
o Generalised –
• GCS, Cardiorespiratory function
o Focal-
• Localising (or false localising) signs.
• PN exam in all head injuries
• Eye exam-
o Anisocoria- which pupil is abnormal?
o VA, Fields, movements, Ant chamber, Post chamber
• Imaging-
o CT

9. A localising sign?
• Helmy, A et al, Fixed, Dilated Pupils Following
Traumatic Brain Injury: Historical Perspectives,
Causes and Ophthalmological Sequelae, Acta
Neurochir Suppl. 2012;114:295-9
o 36 patients with unilateral fixed dilated pupils admitted to a neurosurgical
unit. (Also 24 with BFDP)
o 49%- Diffuse brain injury
o 34%- Ipsilateral lateralising lesion
o 9%- Controlateral lesion
o Unilateral- 49% died, Bilateral- 88% died

10. Prognosis BFDP -
• Scotter et al, Prognosis of patients with fixed dilated
pupils secondary to traumatic extradural or
subdural haematoma who undergo surgery: a
systematic review and meta-analysis, Emerg Med J,
2014
o Based on 5 studies (from 52 meeting the search criteria)
o All were retrospective cohort studies (one study had some prospective
data)
o 82 patients who underwent surgery with BFDPS
• 57- Subdurals
• 25- Extradurals
o Presenting GCS 3-13
o Mean age approx 40, M>F approx 6:1

11. Outcomes
• Extradural-
o Mortality 29.7 (95% CI 14.7-47.2 95%)
o Favourable outcome- 54.3% (95% CI 36.3- 71.8)
• (low-mod disability Glasgow outcome score>4)
• Subdural-
o Mortality 66.4% (95% CI 50.5- 81.9%)
o Favourable outcome 6.6% (95% CI 1.8-14.1%)
• 2 papers had 100% poor outcome

12. Should we believe this
• Small population, limited to specific inclusion
criteria-
o Closed head injury, specific injury, went to OT, BFDP
• Cohort studies- selection bias
o Patients chosen by papers authors- namely the surgeon, likely reflects
better outcomes (of course automatically excludes all the ones not
operated or felt not a good enough candidiate)

13. So….
• Examine carefully in ophthalmology causes, and
consider concurrent intracranial injury.
• Likely localising sign of unilateral FDP not reliable
• Good outcome possible in EDH even if bilateral
fixed dilated pupils
o Likely better with younger age, quicker to OT,
o 54.3% ‘favourable outcome in EDH’
• Probably not so good for subdurals (and likely even
worse for intraparenchymal bleeds) with BFDP.

14. Questions?