Clinical Significance of Isolated Third Cranial Nerve Palsy in Traumatic Brain Injury: A Detailed Description of Four Different Mechanisms of Injury through the Analysis of Our Case Series and Review of the Literature

Abstract

Third cranial nerve palsy (3cnP) following traumatic brain injury (TBI) is a worrying neurological sign and is often associated with an expanding mass lesion, such as extradural or acute subdural haematomas. Isolated 3cnP can be found in the absence of posttraumatic space-occupying mass lesion, yet it is often considered as a devastating prognostic factor in the context of diffuse axonal injury (DAI). Through the analysis of five exemplificative cases and a thorough review of the literature, we identified four possible mechanisms leading to 3cnP: (1) a partial rootlet avulsion at the site of exit from the midbrain, representing a direct shearing injury to the nerve; (2) a direct traction injury due to the nerve stretching against the posterior petroclinoid ligament at the base of the oculomotor triangle secondary to the downward displacement of the brainstem at the time of impact; (3) a direct vascular compression as a result of internal carotid artery (ICA) dissection or pseudoaneurysm; (4) an indirect injury caused by impaired blood supply to the third nerve in addition to the detrimental biochemical effects of the underlying brain injury itself. Understanding the exact mechanism underlying the onset of 3cnP is key to provide an informed clinical decision-making to the patients and ensure their best chances of recovery. Our experience corroborates data from the literature showing that, even in Grade III DAI, prompt recognition of isolated 3cnP can guide adequate treatment. Nonetheless, even when an overall good neurological outcome is achieved, recovery of isolated 3cnP is dismal, and only rarely the visual deficit completely resolves.

Oculomotor nerve palsy presumably caused by cisternal drain during microsurgical clipping

“…Few reports have documented cases of traumatic oculomotor nerve palsy. [ 3 , 6 , 8 , 10 , 17 ] To the best of our knowledge, this is the first case of traumatic oculomotor nerve palsy associated with a cisternal drain. The neuropathy showed remarkable resolution for 50 days after the injury, although photophobia persisted for 6 months.…”

“…[ 2 , 3 , 6 , 8 , 9 , 15 ] Complete recovery from isolated, traumatic oculomotor nerve palsy is generally rare. [ 1 , 10 , 17 ]…”

Traumatic oculomotor nerve palsy treated with transnasal endoscopic decompression through the optic strut

“…Moderate to severe craniocerebral traumas are often accompanied by multiple permanent neurological deficits (19). Uberti et al suggested that traumatic oculomotor nerve injury may be attributed to the following four mechanisms: (1) The nerve root of the midbrain export is directly injured by a rotational shear force, (2) The oculomotor nerve is fixed to the petroclinoid ligament at the lower end of the oculomotor nerve triangle, so a nerve traction injury is directly caused due to the brain stem displacement after trauma, (3) Direct vascular compression is caused due to ICA dissection or pseudoaneurysm, (4) The blood supply to the oculomotor nerve is damaged (20).…”

Isolated Third Cranial Nerve Palsy: Aetiology - Clinical Profile and Recovery at a Tertiary Neuro-ophthalmology Centre on the East Coast Peninsular of Malaysia

“…8,17 In fact, ITCNP may occur in cases of mild head injury, without any neuroimaging abnormality. [18][19] Several mechanisms have been described, either an expanding lesion; such as extradural or subdural haemorrhage, or partial rootlet avulsion, direct traction injury, direct vascular compression or indirect injury due to an impaired blood supply. 19 The incidence of aneurysm as the aetiology of ITCNP is variable in literatures.…”

“…[18][19] Several mechanisms have been described, either an expanding lesion; such as extradural or subdural haemorrhage, or partial rootlet avulsion, direct traction injury, direct vascular compression or indirect injury due to an impaired blood supply. 19 The incidence of aneurysm as the aetiology of ITCNP is variable in literatures. Nevertheless, surgical third nerve palsy is an important warning sign prior to the rupture of an aneurysm: a neurological emergency that is life-threatening.…”