Terson syndrome refers to intraocular haemorrhage in patients with intracranial haemorrhage.

Terminology

The traditional definition of Terson syndrome was vitreous haemorrhage associated with subarachnoid haemorrhage. However, there is also a broader definition which captures intraocular haemorrhages involving various vitreoretinal layers secondary to acutely raised intracranial pressure of various aetiologies but most commonly intracranial haemorrhage ^10,11.

Epidemiology

Terson syndrome has been reported to occur in 13-50% of patients with subarachnoid haemorrhage ^1-3.

Associations

Severe subarachnoid haemorrhage, as demonstrated by a low Glasgow coma scale, a high Hunt and Hess grade, and/or a high Fisher grade, have been found to be associated with a higher incidence of Terson syndrome ⁵.

Intraocular haemorrhage has been reported to occur with subdural haematomas, epidural haematomas, and traumatic brain injury as well ^1,5.

Clinical features

In addition to clinical features of severe subarachnoid haemorrhage, such as headache and coma, patients present with varying degrees of vision loss ⁴. Fundoscopic examination is diagnostic, with patients having evidence of vitreous haemorrhage or other intraocular haemorrhage ¹.

These clinical features usually manifest within the first hour of subarachnoid haemorrhage but can also be delayed by days and even weeks ^5,6.

Pathology

The most accepted pathomechanism of Terson syndrome is retinal venous congestion ¹⁰. According to this theory, a sudden increase in intracranial pressure is transmitted to the cerebrospinal fluid in the optic nerve sheath. Dilation of the sheath obstructs the central retinal vein and retinochoroidal veins, causing retinal venous hypertension and rupture of retinal vessels into the eye.

Because of the close association with subarachnoid haemorrhage, an alternative proposed mechanism of Terson syndrome is that the intraocular haemorrhage originates in the subarachnoid space. Under this theory, elevated intracranial pressure refluxes subarachnoid blood through paravascular glymphatic channels into the globe ¹³.

Location

The intraocular haemorrhage may occur in vitreous, subhyaloid, sub-internal limiting membrane, intraretinal, or subretinal spaces ¹².

Radiographic features

Ultrasound

The red blood cells sediment and compact near the posterior hyaloid surface of detached vitreous and scanning shows echoes of increasing density in the posterior gel. Degenerating blood cells give rise to lower density echoes and colour the posterior vitreous known as Ochre membrane. Subvitreal haemorrhage may sediment to form a fluid level behind the collapsing gel. 

CT

On CT evaluation, retinal nodularity and crescentic hyperdensity, relative to the vitreous humour, in the posterior globe in association with subarachnoid haemorrhage are highly suggestive of this diagnosis ⁷.

Treatment and prognosis

Several months of observation is usually practiced as spontaneous regression of the haemorrhage is seen in up to half of all patients. The condition may require operative intervention with vitrectomy, particularly in the setting of bilateral vitreous haemorrhages ^1,5. The neurological outcome and overall prognosis is worse in subarachnoid haemorrhage patients with Terson syndrome, compared to those without ^1,3,5.

History and etymology

The condition is named after Albert Terson (1867-1935), a French ophthalmologist who described it in 1900 ^3,8. The first case was actually described a few years earlier in 1881 by Moritz Litten (1845-1907), a German physician ^3,9.