A 26-year-old woman with no previous neurological history, asthmatic and on treatment with oral contraceptives, presented with a picture of very intense holocranial headache accompanied by photophobia, nausea and vomiting without fever for about 24 hours of evolution, which was suddenly complicated the following morning with gait instability and diplopia. The neurological examination revealed mild nuchal rigidity, right internuclear ophthalmoplegia, staggering Romberg and left lateropulsion in gait, the rest being normal. A computerised axial tomography was performed, showing a lesion with negative density (-20 to -67 Hounsfield Units) located in the temporal region as well as multiple oval images scattered throughout the right suprasellar cisterns, bilateral quadrigeminae, pontocerebellar angle and frontal horn of the left lateral ventricle, which were interpreted as fat particles. With suspicion of chemical meningitis due to rupture of a dermoid cyst, treatment was started with dexamethasone at a dose of 4 milligrams every 12 hours. A brain MRI scan six days after the onset of symptoms showed an extraparenchymal mass corresponding to the cyst in the medial region of the left temporal pole, ascending to occupy the anterior area of the left perimesencephalic cistern, and dissemination of fat in the subarachnoid space; In addition, a hyperintense image is observed in the paramedial region of the midbrain in the T2-weighted sequences, which is hyperintense in the diffusion sequences and hypointense in the ADC map, compatible with an ischaemic infarction. The MRI is completed with T1 and EGD sequences with fat suppression after gadolinium administration, showing small fat particles scattered in the subarachnoid space; the fat accumulation in the interpeduncular cistern in close contact with the distal part of the basilar and the theoretical exit of the mesencephalic medial perforating branches, superior cerebellar arteries and posterior cerebral arteries is striking. Figure 1 shows a composition with the most representative neuroimaging of the case. Following the results of this test, treatment was started with acetylsalicylic acid at a dose of 100 mg per day and the aetiological study of the stroke was completed with blood tests, haemogram, lipidogram, autoimmunity study, serology, thyroid hormones, homocysteine, anticardiolipin antibodies, B2-microglobulin, antiphospholipid, cerebrospinal fluid study, electrocardiogram, supra-aortic trunk duplex, transcranial Doppler, bubble test, transthoracic echocardiography, arrhythmia holter and angioresonance of Willis polygon; all with normal or negative results.
The headache responded to dexamethasone administration in less than 48 hours and the ophthalmoparesis and instability resolved after 10 days, leaving the patient asymptomatic. The patient was diagnosed with isolated anteromedial mesencephalic infarction possibly secondary to vasospasm of paramedian mesencephalic perforating arteries in relation to subarachnoid dissemination of the fatty content of a ruptured temporal dermoid cyst. In agreement with the patient, the neurosurgery department decided on a wait-and-see attitude and serial neuroimaging controls, leaving elective surgery for the case of the appearance of symptomatology due to tumour compression.