Midbrain Infarction Presenting with Weber's Syndrome and Central

Archives of Neuropsychiatry 2009; 46: 197-9Nöropsikiyatri Arflivi 2009; 46: 197-9Alg›n et al.Midbrain Infarction Presenting with Weber’s Syndrome and Central Facial Palsy: A Case Report 199The preganglionic parasympathetic fibers of the 3 rd nervewhich are transported by the nerve to the inferior obliquemuscle arrive to the ciliary ganglion and from here thepost-ganglionic parasympathetic fibers emerge. The ciliarymuscle and the muscles of the iris are innervated by thesepost-ganglionic parasympathetic fibers. The nerve fibers tolevator palpebrae muscle and the pupilloconstrictor fibers forthe muscles of the iris are located in a superficial and dorsalposition on the nerve relaying in the ciliary ganglion. Beforeexternal ophthalmoplegia develops, a fixed dilated pupil is oftenthe first sign of 3rd nerve (oculomotor) compression, and ptosisthe second, upon this anatomical characteristic (5).The clinical manifestation of the patients with isolatedmesencephalic infarct was shown up nuclear or fascicularoculomotor nerve palsy and contralateral motor deficits (6,7).In patients with isolated mesencephalic infarct, the clinicalpicture was dominated by nuclear or fascicular third-nerve palsyand contralateral motor deficits (6,8).On the other hand the corticobulbar tract (CBT) is commonlyused to describe the pathway taken by motor fibers innervatingthe cranial nerve nuclei, especially trigeminal, facial, hypoglossalmotor nuclei, nucleus ambiguus, and spinal accessorynucleus. The oculomotor, trochlear and abducensnuclei receive no input from the CBT. The cell bodies of primarymotor neurons are located in primary motor cortex (9).The motor nucleus of the facial nerve, which supplies themuscles of the facial expression, is located at the lower pontinelevel, dorsolaterally in the caudal pons (4). The CBT fibers thatconnect the motor cortex with the facial nucleus providestrongly unilateral innervation to the contralateral lower facialmuscles and bilateral innervation to the upper facial muscles.The facial CBT fibers descend at the ventromedial region of thecrus cerebri, near the corticospinal tract (10).The clinical manifestations of midbrain infarcts mostly showthe location of the lesion directly, but these features could notalways match with classical syndromes which describedpreviously in the literature, just like our case that we present inthis report (11).Posterior cerebral artery branch disease may be caused byocclusion of the arterial branch with atherothrombotic plaque(4). In these cases, hypertension is a major risk factor, as seen inour patient (10).Kumral et al. presented the topographic and clinicaldistribution of the acute posterior circulation infarcts involvingmesencephalon. They described four patients with Weber’ssyndrome and central facial palsy due to isolated midbraininfarct around ventromedial crural region within 41 patients withmesencephalic infarction. These were the only cases in theliterature identical to our patient (6).Some minor infarctions at the midbrain which resulted inlocalized paralysis like weakness of a single extraocular muscle(12), isolated contralateral superior rectus palsy (13) have beendemonstrated previously. Some interesting cases, such aspresence of left oculomotor nerve palsy with normal pupil andright hemiparesis, were described. An ischemic lesion of thelower midbrain, which corresponds to the motor nucleus of theoculomotor nerve, was demonstrated in this case (3).Terao et al. reported two patients with contralateral centralfacial paralysis and hemiparesis of the limbs, resulted fromunilateral ventromedial medullary infarction (14). According tothese cases, they described the course of the facial corticobulbartract as consisting of looping fibers that descend at least to themedullary level and then decussate. In another study with largergroup (70 patients), they attempted to further clarify the courseand the distribution of the facial corticobulbar tract (10). But theauthors could not coincide with third nerve palsy or Weber’ssyndrome within these central facial palsy patients.Finally, this report demonstrates an extremely rare case ofcrossed hemiplegia with oculomotor and facial nerve palsy dueto an infarct in the upper part of the midbrain as documented bythe MRI scan. 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