Further observations on the vestibulo-dural channel By GEORGE KELEMEN* (LOS Angeles) and BKRNARD FRAYSSEf (Toulouse) IN serially sectioned temporal bones a hitherto undescribed channel was observed in a number of cases (Kelemen, 1976) opening from the vestibular aqueduct and leading under the dura, it left the aqueduct a short distance before its orifice in the endolymphatic sac, complete with bony walls lined with connective tissue around a continuation of the aqueduct lumen. The present study had a double aim: to find additional instances of the morphology of this phenomenon; and, if possible, to complete the findings, so far described only anatomically, with clinical data. Material and methods
Statistics regarding the frequency of occurrence of this channel were avoided for two reasons: first, the figures were constantly being changed by the arrival of new material; and secondly, as only every tenth section in the series is stained, the possible occurrence in the intermediary nine sections cannot be excluded. The examples, taken from 12 cases presented here, try to reinforce anatomy and topography. One hundred and fifty temporal bone series were scanned, in addition to those described in the abovequoted communication; within this total, the channel was found in 11 instances, the number being influenced by the above-mentioned two considerations. AH the series were sectioned in the horizontal plane, so scanning of vertical series remains desirable. The technical procedures remained as in the earlier communication. Observations
Twelve cases are described, followed by photomicrographs. Case 1 (Fig. 1,72-year-old male)showed a duplication of the operculum. In comparable cases the duplication was sometimes accompanied by duct formation in several directions away from the opening into the saccus. Case 2 (Fig. 2, 53-year-old male). The narrow continuation of the aqueduct was embedded in a very rich connective tissue layer. The channel left from a thick bony wall showing, at its aperture, exostotic protrusions. In Case 3 (Fig. 3, 63-year-old male); Case 4 (Fig. 4, 50-year-old female); Case 5 (Fig. 5, 52-year-old male); Case 6 (Fig. 6, 77-year-old female); and * From the Far Research Institute, Eccles Laboratory, University of Southern California School of Medicine, Los Angeles. t From the Service d'ORL, Hopital Purpan (Prof. Lacomme), Toulouse, France. 757
758
GEORGE KELEMEN AND BERNARD FRAYSSE
Case 7 (Fig. 7, 67-year-old female) the central channel was thin, running its elongated course. In Case 8 (Fig. 8, 60-year-old female) the channel presented an irregular profile. In Case 9 (Fig. 9, 54-year-old male) the branching channel left in the form of a funnel. In Case 10 (Fig. 10, 54-year-old male) the channel was very wide, but still with a narrow central lumen. In Case 11 (Fig. 11, 54year-old male) the interruption of the main aqueduct wall was very wide. In Case 12 (Fig. 12, 12-year-old female) from the wide opening of the aqueduct, two channels were branching off. Cases 10 and 11 originate from the right and left sides of the same individual. Bilateral occurrence was observed several times. It was conspicuous that, in no less than seven of the twelve cases described above, the channel occurred in otosclerotic bones (Cases 1, 3, 7, 9, 10, 11, 12). No connection could be established between the two conditions, and, of course, the otosclerotic focus never reached the region of the channel. Considering the topography of the channel, it was natural to look into the case histories for evidence of Menicre's phenomena. Only two patients showed dizziness among iheir symptoms; one of these (Case 3) had a narrow, but distinctly branching-off channel, the other
FIG. 1 Duplication of the operculum. (x 44)
FIG. 2 Channel, leaving with exostotic thickenings and reaching the dura, (x 24)
FIG. 3 Aqueduct progressing in a richly pneumatized area, ( x 20)
FIG. 4 Thin channel. (x 32)
FIG. 5 Thin channel. ( •; 32)
FIG. 6 Thin channel. (x 40)
FIG. 7 Channel with very elongated course. ( x 30)
..
-.*.—'
FIG. 8 Bony channel with very variegated profile. (x 36)
FIG. 9 Funnel-shaped exit of channel. ( x 30)
FIG. 10 Wide channel araund aqueduct lumen. (x 32)
Fio. 11 Wide opening of the aqueduct wall, (x 32)
764
GEORGE KELEMEN AND BERNARD FRAYSSE
3a.
12 Wide bridge in the aqueduct wall, with two channels branching from it in the direction of the dura. (x 40) FIG.
(Case 6) a distinct channel, but with an irregular bony wall. On the contrary, where Meniere's disease was noted in the history, no branching channel was detected: one case (Case 4) showed ruptured membranes in the vestibule, but without dizziness: another (Case 6), a bulging Reissner's membrane in the middle turn of the cochlea. Other irregularities within the series were: a skull fracture after gunshot (Case 2); a leiomyosarcoma in the temporal bone (Case 8); a widelydilated cochlear aqueduct (Case 12); one case (Case 5) with extensive (nonotosclerotic) ossification in the internal ear; and several cases with mucopurulent infections of various grade. In none of these was it possible to establish any connection between the temporal bone pathology and the phenomenon discussed herein. The only case with a clinical diagnosis of Meniere's disease (Case 6) suffered recurrent vertigo, fluctuating hearing loss, tinnitus and hysterical gait. She underwent labyrinthectomy and on the affected side a channel was noted with only irregular bony walls; the contralateral ear was unaffected by Meniere's disease and there was no channel formation. Tt is possible that a search among congenital ear anomalies would reveal further similar formations.
THE VESTIBULO-DURAL CHANNEE
765
Summary
A channel between the vestibular aqueduct and the dura, corresponding in texture to the main aqueduct, has been observed in an un-negligible number of cases. All attempts to establish a connection between this phenomenon and a variety of clinical entities, among them Meniere's disease, have so far been unsuccessful. REFERENCE KELEMEN, G. (1976) Journal of Laryngology and Otology, 90, 1071.
Statistics regarding the frequency of occurrence of this channel were avoided for two reasons: first, the figures were constantly being changed by the arrival of new material; and secondly, as only every tenth section in the series is stained, the possible occurrence in the intermediary nine sections cannot be excluded. The examples, taken from 12 cases presented here, try to reinforce anatomy and topography. One hundred and fifty temporal bone series were scanned, in addition to those described in the abovequoted communication; within this total, the channel was found in 11 instances, the number being influenced by the above-mentioned two considerations. AH the series were sectioned in the horizontal plane, so scanning of vertical series remains desirable. The technical procedures remained as in the earlier communication. Observations
Twelve cases are described, followed by photomicrographs. Case 1 (Fig. 1,72-year-old male)showed a duplication of the operculum. In comparable cases the duplication was sometimes accompanied by duct formation in several directions away from the opening into the saccus. Case 2 (Fig. 2, 53-year-old male). The narrow continuation of the aqueduct was embedded in a very rich connective tissue layer. The channel left from a thick bony wall showing, at its aperture, exostotic protrusions. In Case 3 (Fig. 3, 63-year-old male); Case 4 (Fig. 4, 50-year-old female); Case 5 (Fig. 5, 52-year-old male); Case 6 (Fig. 6, 77-year-old female); and * From the Far Research Institute, Eccles Laboratory, University of Southern California School of Medicine, Los Angeles. t From the Service d'ORL, Hopital Purpan (Prof. Lacomme), Toulouse, France. 757
758
GEORGE KELEMEN AND BERNARD FRAYSSE
Case 7 (Fig. 7, 67-year-old female) the central channel was thin, running its elongated course. In Case 8 (Fig. 8, 60-year-old female) the channel presented an irregular profile. In Case 9 (Fig. 9, 54-year-old male) the branching channel left in the form of a funnel. In Case 10 (Fig. 10, 54-year-old male) the channel was very wide, but still with a narrow central lumen. In Case 11 (Fig. 11, 54year-old male) the interruption of the main aqueduct wall was very wide. In Case 12 (Fig. 12, 12-year-old female) from the wide opening of the aqueduct, two channels were branching off. Cases 10 and 11 originate from the right and left sides of the same individual. Bilateral occurrence was observed several times. It was conspicuous that, in no less than seven of the twelve cases described above, the channel occurred in otosclerotic bones (Cases 1, 3, 7, 9, 10, 11, 12). No connection could be established between the two conditions, and, of course, the otosclerotic focus never reached the region of the channel. Considering the topography of the channel, it was natural to look into the case histories for evidence of Menicre's phenomena. Only two patients showed dizziness among iheir symptoms; one of these (Case 3) had a narrow, but distinctly branching-off channel, the other
FIG. 1 Duplication of the operculum. (x 44)
FIG. 2 Channel, leaving with exostotic thickenings and reaching the dura, (x 24)
FIG. 3 Aqueduct progressing in a richly pneumatized area, ( x 20)
FIG. 4 Thin channel. (x 32)
FIG. 5 Thin channel. ( •; 32)
FIG. 6 Thin channel. (x 40)
FIG. 7 Channel with very elongated course. ( x 30)
..
-.*.—'
FIG. 8 Bony channel with very variegated profile. (x 36)
FIG. 9 Funnel-shaped exit of channel. ( x 30)
FIG. 10 Wide channel araund aqueduct lumen. (x 32)
Fio. 11 Wide opening of the aqueduct wall, (x 32)
764
GEORGE KELEMEN AND BERNARD FRAYSSE
3a.
12 Wide bridge in the aqueduct wall, with two channels branching from it in the direction of the dura. (x 40) FIG.
(Case 6) a distinct channel, but with an irregular bony wall. On the contrary, where Meniere's disease was noted in the history, no branching channel was detected: one case (Case 4) showed ruptured membranes in the vestibule, but without dizziness: another (Case 6), a bulging Reissner's membrane in the middle turn of the cochlea. Other irregularities within the series were: a skull fracture after gunshot (Case 2); a leiomyosarcoma in the temporal bone (Case 8); a widelydilated cochlear aqueduct (Case 12); one case (Case 5) with extensive (nonotosclerotic) ossification in the internal ear; and several cases with mucopurulent infections of various grade. In none of these was it possible to establish any connection between the temporal bone pathology and the phenomenon discussed herein. The only case with a clinical diagnosis of Meniere's disease (Case 6) suffered recurrent vertigo, fluctuating hearing loss, tinnitus and hysterical gait. She underwent labyrinthectomy and on the affected side a channel was noted with only irregular bony walls; the contralateral ear was unaffected by Meniere's disease and there was no channel formation. Tt is possible that a search among congenital ear anomalies would reveal further similar formations.
THE VESTIBULO-DURAL CHANNEE
765
Summary
A channel between the vestibular aqueduct and the dura, corresponding in texture to the main aqueduct, has been observed in an un-negligible number of cases. All attempts to establish a connection between this phenomenon and a variety of clinical entities, among them Meniere's disease, have so far been unsuccessful. REFERENCE KELEMEN, G. (1976) Journal of Laryngology and Otology, 90, 1071.
