Pupillary dilatation in head injury-

The significance and prognosis

Tom BK Feb 2015

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!

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

Herniation

1) Uncal (transtentorial)2) Central3) Cingulate (subfalcine)4) Upward (transtentorial)5) Tonsillar

Falx cerebri

Tentorium cerebelli

Foramen magnum

Causeso 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

Herniation

1) Uncal (transtentorial)2) Central3) Cingulate (subfalcine)4) Upward (transtentorial)5) Tonsillar

Falx cerebri

Tentorium cerebelli

Foramen magnum

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

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

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,

2014o 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

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

Should we believe this• Small population, limited to specific inclusion

criteria-o Closed head injury, specific injury, went to OT, BFDP

• Cohort studies- selection biaso 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)

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 pupilso 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.

Questions?