Reverse Locked-In Syndrome

Abstract

Background: Basilar artery occlusion can cause locked-in syndrome, which is characterized by quadriplegia, anarthria, and limited communication via eye movements. Here, we describe an uncommon stroke syndrome associated with endovascular recanalization of the top of the basilar artery: "reverse locked-in syndrome."

Methods: We report the case of a patient with atypical neurological deficits caused by acute ischemic stroke of the midbrain tegmentum. We perform neuroanatomic localization of the patient's infarcts by mapping the magnetic resonance imaging (MRI) data onto a brainstem atlas.

Results: A 61-year-old man presented with acute coma and quadriplegia due to top of the basilar artery occlusion. He underwent emergent endovascular thrombectomy, with successful recanalization of the basilar artery at 4 h and 43 min post-ictus. The patient regained consciousness and purposeful movement in all four extremities, but the post-procedure neurological examination demonstrated bilateral ptosis with complete pupillary and oculomotor paralysis. MRI revealed infarction of the bilateral oculomotor nuclei in the midbrain tegmentum. At 9-month follow-up, he had anisocoria and dysconjugate gaze, but was living at home and required minimal assistance in performing all activities of daily living.

Conclusions: Since the patient's deficits were the exact opposite of those described in locked-in syndrome, we propose the term "reverse locked-in syndrome" to describe this neurological entity characterized by bilateral ptosis, non-reactive pupils, and ophthalmoplegia with preservation of consciousness and extremity motor function.

Keywords: Endovascular thrombectomy; Locked-in syndrome; Midbrain tegmentum; Ophthalmoparesis; Top of the basilar artery.

Fig. 1

A hyperdense top of the basilar artery is seen on axial and coronal images from the noncontrast head computed tomography (CT) scan in panels A and B, respectively (red arrows). A contrast filling defect is seen at the top of the basilar artery and bilateral posterior cerebral arteries on axial and coronal sections of the CT angiogram in panels C and D, respectively (red arrows).

Fig. 2

Cerebral angiography with anteroposterior view of a right vertebral artery injection demonstrates a contrast filling defect at the top of the basilar artery (red arrow), right posterior cerebral artery and very mild opacification of the left posterior cerebral artery (panel A). Post-thrombectomy anteroposterior view of a right vertebral artery injection reveals anterograde flow in the basilar and bilateral posterior cerebral arteries, thalamoperforator branches and bilateral superior cerebellar arteries (panel B). There is a small, residual non-occlusive filling defect at the distal, left aspect of the basilar artery (red arrow), without evidence of impairing flow to the left posterior cerebral artery. Panel C shows the penumbra catheter being passed from the right vertebral artery to the right posterior cerebral artery past the basilar artery thrombus (red arrow-head). Two pieces of thrombus, each approximately 5 mm in maximal diameter, were aspirated (Panel D).

Fig. 3

Infarct Lesion Mapping. The brainstem and thalamic components of the infarct are shown on the diffusion-weighted images (top row, A–D) and on an atlas of brainstem nuclei, onto which the infarct was manually traced (bottom row, E–H). The infarct appears hyperintense on the diffusion-weighted images and is shown in white on the Harvard Ascending Arousal Network Atlas (www.martinos.org/resources/aan-atlas). The following cranial nerve nuclei and fasciculi are shown on the atlas: cranial nerve III (purple, F), medial longitudinal fasciculus (blue, F–G), and rostral interstitial nucleus of the medial longitudinal fasciculus (pink, G). The infarct overlaps with each of these nuclei and fascicles bilaterally. Also shown on the atlas are arousal nuclei of the ascending arousal network: pedunculopontine nucleus (purple, E), ventral tegmental area (pink, E), dorsal raphe (turquoise, E), and midbrain reticular formation (red, F–G). Except for a small region of the midbrain reticular formation that overlaps with the infarct (F–G), the infarct spares the arousal nuclei, which may explain the patient’s rapid recovery of consciousness after initially presenting in a coma.