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Show !oumnl orC/il/iml Neurcl-CJI,lttlrnllllvlo,(v 6(2): 12/1-1.31. 1986. Presentation of Pinealoblastoma with Ocular Dipping and Deafness Pradip Toshniwal, M.D., Rita Yadava, M.D., and Hilda Goldbarg, M.D. © 1986 Raven Press, New York Ocular dipping and deafness as presenting manifestations in a patient with pinealoblastoma are highly unusual. Presence of a discrete lesion allows us to postulate a mechanism to explain ocular dipping in light of the present understanding of vertical eye movement control. A mechanism for deafness, probably a false localizing sign of raised intracranial pressure, is proposed also. From the Divisions of Neurology (P.T.) and Child Neurology (R. Y., H.G.), Cook County Hospital, Chicago, Illinois. Add.ress c~r~e~pondence and reprint requests to Pradip Toshmwal, DIVISion of Neurology, 1825 West Harrison Street, Chicago. IL 60612, U.S.A. 128 The clinical features of pinealomas are generally well characterized. The related ocular manifestations are referred to as the dorsal midbrain syndrome or Parinaud syndrome and include selective upgaze dysfunction, pupillary light near dissociation, and convergence retraction nystagmus (1-3). The recent advances in the understanding of the anatomic and physiologic substrate of vertical gaze have allowed improved understanding of the gaze disorders found with pineal lesions (4-6). Here, we describe a patient with pinealoma who presented with binocular conjugate, slow downward drifts with rapid upward movements to primary position and preserved horizontal gaze. These features previously have been termed inverse ocular bobbing or ocular dipping and have been described in association with metabolic and anoxic encephalopathy (7-8). Diffuse neurologic dysfunction in those patients has made the understanding of the underlying mechanism difficult. The discrete localization in the present patient allows us to postulate a mechanism to explain ocular dipping in light of the present concept of the physiology of upgaze. The other unusual feature of the present case is deafness which has been described previously as a nonlocalizing sign of raised intracranial pressure. No explanation, however, is available. In the present patient, electrophysiological evidence of cochlear dysfunction was found and a possible underlying mechanism is discussed. CASE REPORT An 8-year-old girl was well until 4 months prior to admission, when she developed headache, vomiting, progressive hearing loss, tinnitus, and weight loss. Her hearing deteriorated rapidly over the last month. Her school performance dropped and she resorted to using sign language. A PINEALOBLASTOMA WITH OCULAR DIPPING /29 hearing test showed profound, bilateral sensorineural hearing loss. Two days prior to admission, she developed staggering gait and fluttering of her eyes. Her general physical examination was normal. Neurological examination showed her to be alert and cooperative. No response to speech or sounds could be obtained. Pupils were equal and reactive to light and accommodation. Funduscopy showed bilateral papilledema. Extraocular movements showed normal range of smooth pursuit and saccadic movements in all directions. There were frequent, but intermittent spontaneous binocular conjugate downward drifts from the primary position, with rapid upward movements back to the primary position. Her gait was wide-based and she could not walk in tandem. The rest of her neurological examination was normal. Computerized tomographic (CT) scan, as well as magnetic resonance imaging, showed a round, well-circumscribed extra-axial mass in the quadrigeminal cistern, in relation with the dorsal midbrain, but not infiltrating it (Figs. 1 and 2). Audiologic evaluation showed profound sensorineural hearing loss. No response was obtained on attempted brainstem auditory-evoked responses. A ventriculoperitoneal shunt was placed, followed by resection of the mass and radiation therapy to the craniospinal axis. Histology showed features suggestive of a pinealoblastoma. On follow-up, the child continues to have the hearing impairment, but no abnormal eye movements. Repeat CT shows no evidence of residual or recurrent tumor mass. Brainstem auditoryevoked responses continue to be absent. DISCUSSION The patient described is of considerable interest because of the unusual presenting symptoms in the face of otherwise typical neuroradiologic and pathologic features of a pineal tumor. The constellation of ocular abnormalities associated with the lesions of pineal gland has been variously termed the dorsal midbrain syndrome, pretectal syndrome, or Parinaud syndrome (1-3). The cardinal features consist of disturbance of vertical gaze, convergence retraction nystagmus on attempted upgaze, and light near dissociation of the pupillary response. The abnormalities of vertical gaze have been characterized by Baloh et al. by means of electro-oculographic studies which demonstrated hypometria of upward saccades (4). Saccade velocity did not correlate with the degree FIG. 1. Axial CT scan shows a contrast enhancing mass in the region of the quadrigeminal cistern. of limitation of upward gaze; upward pursuit consistently reached a higher gaze position than upward sacca des, but frequently showed abnormality of gain (peak eye velocity/peak target velocity). Reflex vertical movements, i.e., vestibular, optokinetic, and visual-vestibular, on the other hand, were relatively preserved. The understanding of the eye movement abnormalities described has advanced considerably due to the elegant anatomical and physiological studies of Buttner and Buttner-Ennever (9-11). While only parapontine reticular formation contains long-lead burst neurons and omnipause neurons and is, therefore, important in the generation of vertical saccades, high-frequency burst or pulse neurons, responsible for presaccadic motor activity preceding vertical saccades, are found in the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF). Anatomical connection between riMLF and the oculomotor nuclei, particularly to areas supplying vertical muscles, have been demonstrated. Within the riMLF, the burst cells responsible for upward and downward gaze do not show anatomic segregation. The frequently observed selective involvement of upward gaze has been explained on the basis of possible segregation of efferent pathways I C/ill Nturl>-opllt1lolmol. Vol. 6. No.2. 1986 130 P. TOSHN/WAL ET AL. FIG. 2. Magnetic resonance imaging in midsagittal plane demonstrates the relation of the mass to dorsal midbrain. The lesion is extra-axial and noninfiltrative. to the oculomotor nuclei. It has been suggested that the fibers responsible for upgaze leave the riMLF dorsolaterally, decussate in the posterior commissure, and project to the oculomotor nuclei bilaterally (5,6). The long tortuous course, as well as the dorsal location of these fibers with resultant spatial proximity to the pineal, explains the selective involvement of upgaze with pineal lesions. The present concept of eye movement control suggests a need for signals encoding both eye velocity and eye position. The premotor inputs encode velocity signal which then is integrated into a position-coded signal (12). It is postulated that tonic neurons in pontine reticular formation provide the position signal (13). The discharge frequency of neurons within the oculomotor nuclei varies linearly with eye position during fixation and, during movements, is modulated in proportion to eye velocity (14). In the monkey, vertical tonic-pause fibers constitute about 45% of the medial longitudinal fasciculus, fire at rates proportional to the vertical eye position, and appear to be nonsegregated with respect to up- or downward movement (15). Also, in the monkey, burst tonic neurons are identified in the accessory oculomotor nuclei (interstitial nucleus of Cajal, nuclei of the posterior commissure, nucleus of Darkschewitsch), and the adjacent mesencephalic reticular formation (16). Once again, units with upward or downward on-directions were not found to be segregated. However, oculomotor nucleus afferents from the above nuclei have been shown to , eJi" N<,lIr(l·(I/,1II'lallllol. Vol. 6. No.2. 1986 be segregated, just like those from the riMLF, with those concerned with upgaze passing in the posterior commissure (17). In the patient described, frequent, spontaneous downward slow drifts may represent imbalance of upward and downward coded tonic signals to the oculomotor nuclei due to predominant involvement of the dorsal mesencephalon and posterior commissure. The rapid upward movements are likely to be secondary, corrective refixation saccades. On clinical observation, range of upgaze appeared not to be restricted and saccadic and pursuit movements appeared to be normal. While in absence of electro-oculographic recordings it is difficult to draw definite conclusions, the discrepancy between upgaze position and velocity signals remains, nonetheless, intriguing. One may wonder if the oculomotor vertical gaze afferents from the burst neurons and the tonic pause neurons are anatomically segregated or, alternatively, differentially sensitive to pathological processes. In the patients previously described, ocular dipping has been associated with coma, usually following anoxia (Table 1). Subtotal extrapyramidal and cortical damage has been postulated to be the cause of eye movement abnormality (7,8,18,19). Furthermore, change in the frequency of ocular dipping on sensory stimulation has been interpreted as an indication of the involvement of the arousal system and the cerebral structures (18). We believe the presence of diffuse severe cerebral dysfunction neither proves a cause-and-effect rela- PIN£ALOBLASTOMA WITH OCULAR DIPPING 13/ TABLE 1. Summary of reported cases Patient Level of Other neurologic Likely cerebral Reference No. Age consciousness Upgaze features pathology Knobler et al. (7) 37 Comatose ? Status epilepticus, multiple intracranial hematomas Multifocal/diffuse 2 90 Comatose ? Status epilepticus Diffuse Ropper (8) 1 19 Comatose Normal oculocephalic, Anoxic encephalopathy Cortical, extrapyramidal, occasional ?pretectum spontaneous 2 17 Comatose Same Carbon monoxide Putamen on CT Intoxication ?diffuse 3 7 Comatose ? Anoxic encephalopathy Diffuse Van Weerden and Van Woerkam (18) 1 18 Comatose ? Traumatic encephalopathy Multifocalldiffuse 2 4 Comatose Absent. oculocephalic Anoxic encephalopathy Diffuse 3 6 Comatose Present. oculocephalic Anoxic encephalopathy Diffuse Stark et al. (19) 53 Comatose ? Meningitis/micro abscesses, anoxic encephalopathy Multifocal/diffuse Present case 8 Alert Normal Deafness, papilledema Pretectal tionship between the cortical and extrapyramidal dysfunction and the eye movement abnormality nor negates the possibility of a more localized pretectal lesion. Furthermore, the pretectal area Lies in the terminal portion of the arterial supply of the median penetrating branches of the basilar artery and the circumferential arteries and, therefore, may be involved preferentially with circulatory collapse like the other watershed areas in the brain (20). Also, ocular dipping has been described in an awake patient with Wernicke syndrome in association with upgaze palsy (21). It may well be that selective upgaze palsy, ocular dipping, and tonic downward gaze deviation represent various grades of dysfunction of the pretectal area, probably even in the context of more diffuse cerebral abnormality. lhe other unusual feature of the presentation of this case was the deafness. Though described with other brainstem neurological disorders, as well as a false localizing sign with raised intracranial pressure, this symptom remains distinctly unusual and has not been described with pinealoma (22). Brainstem auditory-evoked responses showed absence of any recordable wave form, suggesting cochlear dysfunction. Auditory pathways are known to be sensitive to intracranial pressure, as reflected by the abnormalities of BAERs (23). It has been shown that the endolymphatic sac reflects intracranial pressure because of its communication with the subarachnoid space through the cochlear aqueduct (24,25). The functional corollary of this observation is that cochlear microphonic potential amplitude decreases rapidly with elevation of intracranial pressure (26,27), Under experimental conditions, this effect is rapidly reversible with the decrease in cerebrospinal fluid pressure, but if the pressure is maintained, permanent damage results. The two proposed mechanisms include decreased cochlear blood flow (analogous to decreased optic disc flow and infarction occasionally seen with raised intracranial pressure) and mechanical stretching of the basement membrane. The absence of wave one and subsequent waves in BAERs in this patient suggested cochlear dysfunction. The experimental observations listed above offer a possible explanation. Acknowledgment: The authors thank Dr. James Goodwin, Hlinois Eye and Ear Infirmary, for reviewing the manuscript. REFERENCES I. Glaser J. S. Nellro-ophtllfllll/olt1gy. Hagerstown, MD: Harper & Row, 1978:280-1. 2. Miller N. R. 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