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Show Journal of Neuro- Ophthalmology 16( 4): 281- 285, 1996. 1996 Lippincott- Raven Publishers, Philadelphia Dorsal Midbrain Syndrome due to Mesencephalic Hemorrhage Case Report with Serial Imaging Andrew G. Lee, M. D., Dennis G. Brown, M. D., and Pedro J. Diaz, M. D. Spontaneous, nontraumatic, nonhypertensive, midbrain hemorrhage is an uncommon cause of the dorsal midbrain syndrome. We describe a patient with this syndrome in whom the initial neuroimaging studies failed to clearly identify the lesion. Subsequent magnetic resonance imaging studies disclosed a dorsal midbrain hemorrhage. The patient experienced gradual spontaneous resolution of her dorsal midbrain signs and symptoms over several months. The evolution on serial neuroimaging studies of the dorsal midbrain hemorrhage in this patient is described. Key Words: Dorsal midbrain syndrome- Hemorrhage. Lesions involving the dorsal midbrain classically present with the neuro- ophthalmologic findings of lid retraction, light- near dissociation of the pupils, upgaze saccadic paresis, and convergence retraction nystagmus ( 1- 6). Spontaneous, nontraumatic, nonhypertensive, midbrain hemorrhage is an uncommon cause of the dorsal midbrain syndrome ( 7- 11), and the diagnosis is usually confirmed by the initial neuroimaging study. We describe a patient with this syndrome in whom the initial neuroimaging studies failed to clearly identify the lesion; subsequent magnetic resonance ( MR) imaging studies revealed a dorsal midbrain hemorrhage. Serial neuroimaging demonstrated evolution of the hemorrhage over time. Manuscript received June 9, 1995; accepted September 1, 1995. From the Departments of Ophthalmology, Neurology, and Neurosurgery ( A. G. L.), Baylor College of Medicine; the Section of Neurology ( D. G. B.), Memorial City Medical Center; and the Department of Neuroradiology ( P. J. D.), Baylor College of Medicine, Houston, Texas, U. S. A. Address correspondence and reprint requests to Dr. Andrew G. Lee, Cullen Eye Institute, Departments of Ophthalmology, Neurology, and Neurosurgery, Baylor College of Medicine, 6501 Fannin Street, NC- 200, Houston, TX 77030, U. S. A. CASE REPORT A 48- year- old normotensive woman with a history of carpal tunnel syndrome and migraine headaches presented on June 26, 1994, with acute binocular oblique diplopia. Neurologic examination by one of us ( D. G. B.) revealed a light- near dissociation of the pupils, bilateral lid retraction, bilateral vertical saccadic paresis for upgaze greater than downgaze, mild convergence spasm, convergence- retraction nystagmus on attempted upgaze, and a skew deviation. Oculocephalic testing and forced lid closure ( Bell's phenomenon) resulted in improved vertical movement in each eye. The remainder of the neurologic examination was normal. Computed tomography ( CT) scan of the head, blood pressure measurement, echocardiogram, complete blood count, platelet count, and coagulation studies were all normal. MR imaging and MR angiogram of the head were not felt to be diagnostic of a dorsal midbrain lesion ( Fig. 1A and 281 282 A. G. LEEETAL. B), but a single axial T2- weighted MR image was suggestive of a subtle hyperintense focus at the level of the midbrain ( Fig. 1C). Lumbar puncture revealed normal protein, glucose, and cell counts, a few oligoclonal bands, and positive myelin basic protein. Ophthalmological examination on July 12, 1994, by one of us ( A. G. L.) revealed a visual acuity of 20/ 15 OU. The pupils were 6 mm in size OU with a sluggish pupillary light response; there was a brisk near response OU. Slit- lamp examination and ophthalmoscopy were normal. Motility examination was suggestive of a left fourth nerve palsy, but a skew deviation could not be completely excluded. Prism cover testing revealed a left hyper-tropia of 2 prism diopters at distance; an esotropia of 5 prism diopters at near; an esotropia of 5 prism diopters and a left hypertropia of 5 prism diopters in right gaze; and a left esotropia of 6 prism diopters and a left hypertropia of 2 prism diopters on left gaze. On head tilt to the right, there was a left hypertropia of 5 prism diopters; on head tilt to the left, there was a left hypertropia of 5 prism diopters. There was definite lid retraction in each eye without lid lag in downgaze. Upward saccades were moderately impaired. Convergence- retraction movement in both eyes was elicited on attempted upgaze and on attempted upward sac-cades in response to the optokinetic ( OKN) drum rolling downward. There was a mild defect in downward saccades, but smooth pursuit was intact. A second MR scan was performed on July 11, 1994; it revealed a definite hyperintense focus on FIG. 1. Nonenhanced, spin echo, T1- weighted sagittal ( A) and coronal ( B) MR images of brain from June 27, 1994, do not show any definite abnormalities of the dorsal midbrain. Axial spin echo, T2- weighted image ( C) from June 27, 1994, suggests a possible hyperintense focus adjacent to the cerebral aqueduct in the right dorsal midbrain ( arrow). ; Neuro- Ophthtilmol, Vol. 16, No. 4, 1996 POSTHEMORRHAGE MIDBRAIN SYNDROME 283 both Tl- weighted and T2- weighted images at the level of the right dorsal midbrain ( Fig. 2). Cerebral angiography was not performed. One week later, neuro- ophthalmological examination showed improved elevation and depression in both eyes; an esotropia of 1 prism diopter and a right hyperphoria of 1 prism diopter; bilateral lid retraction; and light- near dissociation of the pupils. Convergence- retraction nystagmus could not be elicited, and the remainder of the ocular examination was normal. On November 7, 1994, five months after presentation, T2- weighted coronal and axial MR images ( Fig. 3) revealed a hypointense focus in the right dorsal midbrain, which was felt to be related to the presence of hemosiderin and interval hemorrhage evolution. The patient had minimal residual lid retraction, a mild light- near dissociation of the pupils, and a normal motility examination; she was visually asymptomatic. DISCUSSION The common features of the dorsal midbrain syndrome in our patient included bilateral lid retraction, light- near dissociation of the pupils, up-gaze saccadic paresis, a hyperdeviation possibly due to a fourth nerve palsy or a skew deviation, and a convergence- retraction movement on attempted upgaze. A number of conditions have been reported in association with the dorsal midbrain syndrome, including pineal region neoplasms ( 1), obstructive hydrocephalus ( 2), aneurysm ( 3), and dorsal midbrain infection ( 1), infarction ( 4), or demyelination ( 5). Although brain stem infarction and thalamic hemorrhage with brain stem involvement have been reported in association with a clinical dorsal midbrain syndrome ( 4,6), isolated midbrain hemorrhage is an uncommon cause for the syndrome ( 7- 11). Sand et al. ( 8) reported three cases of nontraumatic, nonhypertensive dorsal midbrain hemorrhages: one patient had a dorsal midbrain syndrome due to a unilateral hemorrhage in the rostral tectal plate; one had a vertical gaze palsy, skew deviation, and a bilateral oculosympathetic paresis due to a unilateral hemorrhage of the superior col-liculus, midbrain tegmentum, and rostral dorsal pons; and one had bilateral fourth cranial nerve palsies, a unilateral oculosympathetic paresis, and ijsirT' FIG. 2. Nonenhanced, spin echo, T1- weighted sagittal ( A) and axial ( B) MR images from July 11, 1994, demonstrate a hyperintense focus in the right dorsal midbrain ( arrows). Coronal T2- weighted axial image ( C) from July 11, 1994, reveals a hyperintense focus at the level of the dorsal midbrain on the right, consistent with the presence of extracellular methemo-globin ( arrow). / Neuro- Ophthalmol, Vol. 16, No. 4, 1996 284 A. G. LEE ET AL. FIG. 3. T2- weighted coronal ( A) and axial ( B) MR images from November 7, 1994, reveal a markedly hypointense focus in the dorsal midbrain on the right, consistent with the presence of hemosiderin related to hematoma evolution ( arrows). ataxia due to a hemorrhage in the caudal tectal plate. The neuro- ophthalmologic findings improved in one patient but were unchanged in the other two. All had initial neuroimaging studies consistent with hemorrhage, but none of these cases had abnormal cerebral angiography. Sand et al. postulated that a " cryptogenic" arteriovenous malformation ( AVM) was the source of the hemorrhage ( 8). Durward et al. reported two cases of mesencephalic hematoma with upgaze paralysis that they felt was due to a brain stem AVM ( 9). La Torre et al. reported a hematoma of the quadrigeminal plate due to a cryptic AVM associated with impairment of upgaze ( 10). Weisberg ( 11) described six cases of normotensive mesencephalic hemorrhages: all six had impaired upgaze and unequal pupils that reacted poorly to light; two had downward ocular deviation; three had ptosis; and one had limited abduction suggesting a " bilateral ab-ducens paresis." Five patients spontaneously improved, and the remaining one improved after insertion of a diversionary shunt ( 11). McCormick et al. reported six mesencephalic angiomas out of 68 total brain stem angiomas including two AVMs, one cavernous angioma, and three venous angiomas. Twelve of 68 ( 18%) brainstem angiomas in this series had bled ( 12). It is not known if our patient had an occult midbrain AVM, and cerebral angiography was not performed. In 1993, Link et al. reported seven cases of spontaneous midbrain hemorrhage and reviewed 66 additional cases from the literature ( 13). They reported neuro- ophthalmologic abnormalities in 58 of 66 patients ( 88%); conjugate upward gaze paresis was present in 33 of these 58 patients ( 57%). The temporal profile of symptoms in these patients was acute (< 24 h) in 65%, subacute ( 1 day to 1 month) in 24%, and chronic (> 1 month) in 11%. The prognosis was good for the majority of the patients. After a mean follow- up period of 9.4 months, 16 patients ( 24%) were neurologically normal, 35 patients ( 53%) had minor neurologic deficits, 10 patients ( 15%) had moderate neurologic deficits, 3 patients ( 5%) had died, and 2 patients ( 3%) had no available follow- up information. None of the seven cases reported by Link et al. had delayed neuroimaging findings ( 13). Evolving intracranial hemorrhage may be classified as hyperacute (< 24 h), acute ( 1- 3 days), early subacute ( 3- 7 days), late subacute ( 7- 14 days), and chronic (> 14 days). The MR signal characteristics in each stage are associated with different forms of hemoglobin. In the hyperacute stage, intracellular oxyhemoglobin results in signal characteristics that are isointense to brain on Tl- weighted images and slightly hyperintense on T2- weighted images. In the acute stage, intracellular oxyhemoglobin becomes deoxyhemoglobin, and the hemorrhage becomes slightly hypointense on Tl- weighted images and very hypointense on T2- weighted images. In the subacute stages, intra- and extracellular methemoglobin are hyperintense on Tl-weighted images. On T2- weighted images, intracellular methemoglobin is very hypointense, and extracellular methemoglobin is hyperintense. Hemosiderin is the classic finding in chronic hemorrhage and is seen as a hypointense rim on T2- weighted images ( 14- 16). In our patient, the lesion was hyperintense on Tl- and T2- weighted im- / Neuro- Ophthalmol, Vol. 16, No. 4, 1996 POSTHEMORRHAGE MIDBRAIN SYNDROME 285 ages on July 11, 1994, and was hypointense on T2- weighted images on November 7, 1994, consistent with evolving hemorrhage. The clinical signs and symptoms of the dorsal midbrain syndrome have specific localizing value, and careful directed neuroimaging studies usually will disclose an etiology. In patients without a definite lesion on initial studies, repeat neuroimaging of the dorsal midbrain may be indicated. The close anatomic relationship of multiple important neurologic structures within the relatively compact dorsal midbrain may account for the presence of pronounced clinical signs even in patients with a small lesion. In addition, a small lesion in the dorsal midbrain may be missed or overlooked on an initial neuroimaging study ( 13). We have described serial neuroimaging in a patient with the dorsal midbrain syndrome secondary to a mesencephalic hemorrhage in whom the initial CT and MR scan were not diagnostic. Her symptoms and signs gradually improved without treatment, and serial neuroimaging studies were consistent with evolving hemorrhage. REFERENCES 1. Baloh R. Dorsal midbrain syndrome: clinical and oculo-graphic findings. Neurology 1985; 35: 54. 2. Chattha A, DeLong G. Sylvian aqueduct syndrome as a sign of acute obstructive hydrocephalus in children. / Neurol Neurosurg Psychiatry 1975; 38: 288- 96. 3. CoppetoJ, Lessell S. Dorsal midbrain syndrome from giant aneurysm of the posterior fossa: report of two cases. Neurology 1983; 33: 732. 4. Sullivan H, Harbison J, Becker D. Parinaud's syndrome: cerebrovascular disease as a common etiology: analysis of 16 cases. Surg Neurol 1976; 6: 301. 5. Sly man J, Kline L. Dorsal midbrain syndrome in multiple sclerosis. Neurology 1981; 31: 196. 6. Waga S, Okada M, Yamamoto Y. Reversibility of Parinaud's syndrome in thalamic hemorrhage. Neurology 1979; 29: 407. 7. Chambers AA, Milennan JE. Pericollicular syndrome. Neuroradiology 1978; 16: 547. 8. Sand JJ, Biller J, Corbett JJ, Adams HP, Dunn V. Partial dorsal mesencephalic hemorrhages. Report of three cases. Neurology 1986; 36: 529. 9. Durward Q, Barnett HJM, Barr HWK. Presentation and management of mesencephalic hematoma. / Neurosurg 1982; 56: 123- 7. 10. La Torre E, Delitala A, Sorano V. Hematoma of the quad-rigeminal plate. / Neurosurg 1978; 49: 610- 3. 11. Weisberg L. Mesencephalic hemorrhages: clinical and CT correlations. Neurology 1986; 36: 713. 12. McCormick W, Hardman J, Boulter T. Vascular malformations (" angiomas") of the brain with special reference to those occurring in the posterior fossa. / Neurosurg 1968; 28: 241- 51. 13. Link MJ, Bartleson JD, Forbes G, Meyer FB. Spontaneous midbrain hemorrhage: report of seven new cases. Surg Neurol 1993; 39: 58- 65. 14. Gomori JM, Grossman RI, Goldberg HI, Zimmerman RA, Bilaniuk LT. Intracranial hematomas: imaging by high- field MR. Radiology 1985; 157: 87- 93. 15. Bradley WG. MR appearance of hemorrhage in the brain. Radiology 1993; 189: 15- 26. 16. Chaney RK, Taber KH, Orrison WW, Hayman LA. Magnetic resonance imaging of intracerebral hemorrhage at different field strengths. Neuroimaging Clin North Am 1992; 2: 25- 51. / Neuro- Ophthalmol, Vol. 16, No. 4, 1996 |
