The correct answer is:

Central venous thrombosis

Educational Objective:

Recognize the symptoms and diagnostics associated with cerebral venous thrombosis.

Key Point:

Cerebral venous thrombosis is associated with headaches and many neurologic findings. It is important to remember this entity and that, even once subarachnoid hemorrhage has been ruled out, serious underlying pathology may exist, and neurologic consult is indicated.

Explanation:

The trochlear nerve innervates the superior oblique muscle, which moves the eye down and laterally while also providing medial rotation (see below image). When it is damaged, the eyeball tends to drift up due to unopposed superior rectus muscle function (CN III). This leads to head tilt in an attempt to bring both eyes back into the same horizontal plane. Even though the trochlear nerve contributes to lateral eye movement, palsy of this nerve is not sufficient to lose all lateral movement. The above patient must also have an abducens nerve (CN IV) palsy, which is causing the lack of lateral gaze. Both of these nerves (and often also oculomotor nerve CN III) are often affected by cavernous sinus thrombosis.

Central venous thrombosis is a rare disease and can have multiple neurologic findings. Headache is the most prominent. Papilledema is a helpful diagnostic sign, but it is present in less than one-half of cases. Likewise, seizure with headache may be indicative, but it is present only 50% of the time.

In Cotard delusion, patients believe they are already dead and can usually smell the stench of their own corpse.

Malingering is not feasible because voluntary control of the extraocular muscles is not unilateral.

Ammonia poisoning gives primarily respiratory symptoms. With a normal blood sugar, diabetic neuropathy is also unlikely.

Figure 1. 

The above image comes from an educational video about eye movements.

References:

Stettler B. Brain and cranial nerve disorders. In: Walls RM, et al. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 9th ed., 2018:1289-1297.e2.