Pupillary dilatation in head injury

Pupillary dilatation in head injury

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

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

3. Causes Intracranial 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 ’ 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

4. Herniation Uncal ( transtentorial ) Central Cingulate ( subfalcine ) Upward ( transtentorial ) Tonsillar Falx c erebri Tentorium cerebelli Foramen magnum

5. Causes Tonsillar herniation (‘coning’) Compression of lower brainstem and upper cord. Pressure on CV + resp centres- cardiorespiratory arrest – Bilateral dilated pupils 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

6. Herniation Uncal ( transtentorial ) Central Cingulate ( subfalcine ) Upward ( transtentorial ) Tonsillar Falx c erebri Tentorium cerebelli Foramen magnum

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

8. 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 36 patients with unilateral fixed dilated pupils admitted to a neurosurgical unit. (Also 24 with BFDP) 49%- Diffuse brain injury 34%- Ipsilateral lateralising lesion 9%- Controlateral lesion Unilateral- 49% died, Bilateral- 88% died

9. 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 Based on 5 studies (from 52 meeting the search criteria) All were retrospective cohort studies (one study had some prospective data) 82 patients who underwent surgery with BFDPS 57- Subdurals 25- Extradurals Presenting GCS 3-13 Mean age approx 40, M>F approx 6:1

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

11. Should we believe this Small population, limited to specific inclusion criteria- Closed head injury, specific injury, went to OT, BFDP Cohort studies- selection bias 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 )

12. 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 Likely better with younger age, quicker to OT, 54.3% ‘favourable outcome in EDH’ Probably not so good for subdurals (and likely even worse for intraparenchymal bleeds) with BFDP.

13. Questions?