One and a half syndrome. Occurrence after trauma with computerized tomographic correlation

Ocular motor abnormalities from head trauma

Head injuries cause the hospitalization of 200-300 persons per 100,000 population per year. Ophthalmologists provide diagnostic and therapeutic care to those trauma victims with damage to the globe, optic nerve, orbit, and ocular motor system. Eye movements can be affected by damage at any level of the central nervous system or peripheral motor unit. Comprehensive ocular motor assessment of the trauma patient can substantially contribute to the understanding of the patient's injury, recovery, and rehabilitation. This review examines all aspects of head and face trauma that can lead to ocular motility disturbances.

Bilateral traumatic third nerve palsy

Bilateral palsy of the third cranial nerve in a head-injured patient is described. Delayed computed tomography scanning demonstrated a midline necrotic lesion within the mesencephalon ventral to the aqueduct. The lesion, possibly the sequela of a focal contusion, involved both third nerve nuclear complexes and caused paralysis of their voluntary as well as autonomic functions. Gaze mechanisms and long tracts appeared to be less heavily damaged. The literature dealing with third nerve palsy, particularly bilateral cases, from traumatic and other origins is briefly reviewed.

One-and-a-half syndrome in ischaemic locked-in state: a clinico-pathological study

Five patients with "locked-in" syndrome and dysconjugate palsy of horizontal gaze were studied. In all cases internuclear ophthalmoplegia due to dysfunction or destruction of the median longitudinal fasciculus was combined with an ipsilateral gaze palsy, producing the "one-and-a-half" syndrome. Clinical and electro-oculographic examination suggested involvement of the paramedian pontine reticular formation when all ipsilateral saccades were abolished, when exotropia of the contralateral eye was present, and when vestibular stimulation showed full conjugate deviation to the damaged side. Involvement of the abducens nucleus was suggested when the palsy of ipsilateral gaze was not dissociated on vestibular stimulation. In three cases these clinical deductions were confirmed by the pathological study, which showed a corresponding destruction of the median longitudinal fasciculus, paramedian pontine reticular formation and abducens nucleus. In one case the one-and-a-half syndrome evolved into a total horizontal gaze palsy, which corresponded to involvement of the abducens nucleus contralateral to the initially destroyed paramedian pontine reticular formation. Vertical oculocephalic response disappeared, because of destruction of the median longitudinal fasciculus on both sides (bilateral internuclear ophthalmoplegia). Patients with the locked-in syndrome provide a unique situation in which complex pontine oculomotor disturbances may be studied, because consciousness is preserved. In these patients, dissociated and dysconjugate oculomotor palsy may have been underestimated.