Sudden onset isolated complete third nerve palsy due to pituitary apoplexy

Pituitary apoplexy is characterized by a sudden onset of headache, visual impairment, opthalmoplegia, altered mental status, and hormonal dysfunction. It is a medical emergency caused by acute hemorrhage or infarction of the pituitary gland / tumor.[1]

A rapid rise in intrasellar pressure causes compression of the adjacent cranial nerves resulting in cranial nerve palsy.[2] Isolated complete third nerve palsy due to pituitary apoplexy is uncommon.[3–5] We report a case of a sudden onset of isolated complete third nerve palsy as the presenting sign of pituitary apoplexy.

A 55-year-old male presented with a sudden onset of a drooping right eyelid following an episode of mild-to-moderate headache. On admission, he was conscious and well-oriented to time, place, and person. His vision was 6 / 6 in both eyes and there was a mild bilateral temporal field restriction on confrontation examination. His right pupil was 5 mm in diameter and not reacting to light, while the left pupil was 3 mm and reacting to light. He had complete ptosis on the right side. The right eye was in a down and out position [Figure 1]. His left eye movements were normal. The remaining cranial nerve functions were normal. Magnetic resonance imaging (MRI) of the brain revealed a heterogeneously enhancing pituitary tumor, which was hyperintense on T-1 weighted images and hypointense on T2-weighted images [Figures 2 and 3]. Magnetic resonance angiography (MRA) was normal. Pituitary hormones were within normal levels. The sellar mass was excised via a sublabial transphenoidal approach. The tumor tissue along with altered blood was drained out. A near complete excision of the pituitary adenoma was achieved. The histopathological examination confirmed pituitary adenoma with extensive areas of hemorrhage and necrosis, consistent with apoplexy [Figure 4]. The postoperative course was uneventful and the patient had a good clinical recovery. At the six-week follow-up, the right-sided ptosis and eye movements had completely recovered; however, pupillary dilatation was persistent [Figure 5]. A follow-up MRI of the brain showed no residual adenoma with the chiasm in normal position [Figure 6].

Figure 1.

Photographs showing right side third nerve palsy. A: Primary position. B: Left gaze

Figure 2.

MRI brain sagittal view. A: T-1 weighted imaging showing a hyperintense mass lesion occupying the sellar region. B: T-2 weighted imaging showing a hypointense lesion. C: Post gadolinium sequence showing heterogenous enhancement of the sellar lesion

Figure 3.

Post gadolinium MRI brain in axial (A) and coronal views (B), showing the sellar mass extending into the right cavernous sinus

Figure 4.

Microscopic features of pituitary apoplexy. Photomicrograph shows tumor cells with hemorrhage (Hematoxylin-Eosin stain). (A) ×10 view (B) × 40 view

Figure 5.

Postoperative photographs showing recovery of right-sided third nerve palsy A: Primary position, B: Left gaze

Figure 6.

Postoperative MRI brain (sagittal view): (A) T-1 weighted and (B) T-2 weighted images showing no residual adenoma with chiasm in the normal position

Ophthalmic manifestations in pituitary apoplexy result from the expansion of the tumor in the lateral and / or superior direction. Multiple cranial nerve palsies (III, IV, V, VI) occur from the lateral expansion of the pituitary tumor, while superior expansion results in dysfunction of the optic nerve and optic chiasm.

The occulomotor nerve is more susceptible to laterally transmitted pressure by expanding the pituitary mass, because of its anatomical location. Slow onset third nerve palsy results from either gradual compression of the nerve in the sinus wall or direct infiltration of the nerve by the pituitary tumor. Sudden onset third nerve palsy results from hemorrhage or infarct in the pre-existing pituitary mass and is attributed to the compromising of the vascular supply of the nerve, due to compression of the vasa nervosum originating in the internal carotid artery.[6]

The most common cause of sudden onset third nerve palsy is the posterior communicating (Pcom) artery aneurysm. The differential diagnosis includes intracranial hemorrhage, subarachnoid hemorrhage, bacterial meningitis, cavernous sinus thrombosis, and midbrain infraction.

Treatment of pituitary apoplexy includes medical and surgical management.[5] Intravenous steroid is necessary to prevent acute adrenal insufficiency. The definitive treatment for pituitary apoplexy is early surgical decompression, which relieves the pressure on the sellar and suprasellar structures.

Pituitary apoplexy should be considered early in the differential diagnosis of sudden onset isolated complete third nerve palsy. Early diagnosis and prompt neurosurgical decompression can restore pituitary function and result in good clinical recovery of the third nerve function.