Unique case of midbrain tuberculoma presenting as isolated inferior rectus palsy with nystagmus

Abstract

Isolated brain stem tuberculoma constitutes about 5% of all intracranial tuberculomas. A case of isolated inferior rectus palsy with downbeat nystagmus due to presumed midbrain tuberculoma in an immunocompetent patient is described here. This report documents a rare entity of a combination of partial third nerve palsy with pupil involvement along with downbeat nystagmus.

Comment on: Unique case of midbrain tuberculoma presenting as isolated inferior rectus palsy with nystagmus

“…conflate a ‘unique’ presentation that raises many quintessential issues. [ 1 ] The association with nystagmus by itself renders inferior rectus palsy (IRP) as nonisolated. Subsequently, a definitive diagnosis of pupil involving partial third nerve palsy with downbeat nystagmus was made abandoning even IRP.…”

“…Diplopia chart betrays an undocumented horizontal crossed diplopia due to exotropia likely emanating from unilateral/bilateral internuclear ophthalmoparesis (INO), it is not due to medial rectus under-action due to third nerve palsy as it is comitant, both are thus in conflict. [ 1 ] The 9 gaze montage neither betrays muscle sequalae consistent with acute onset IRP, nor is there any a pattern strabismus, AHP is sans face turn and chin depression, frequently seen in IRP. [ 2 ]…”

“…[ 4 5 ] All emanate from ischemic microinfarcts; accordingly, authors contention that a huge tuberculoma led to such an isolated involvement is untenable. [ 1 ]…”

“…Nystagmus is not downbeat as contended since it is absent in PP. [ 1 ] Gaze evoked vertical conjugate nystagmus militates against a diagnosis of third nerve palsy and further attests to involvement of INC, a structure crucial for vertical gaze holding and reflecting a leaky brainstem integrator. Pupil involvement, INO, and nystagmus have been reported with skew deviations[ 8 ] and are likely fellow travelers in this case.…”