Fluoreszenzangiographie des Trommelfelles - Entwicklung der Methode und Normalbefunde

Pressure changes in the human middle ear without opening the eustachian tube

CONCLUSION

By means of a direct, though non-invasive experiment on healthy humans we could demonstrate that middle ear (ME) pressure decreases when the eustachian tube (ET) does not open. Thus with a very simple method the basic theory of continuous gas loss from the ME into the circulation and the replenishment of the loss through the ET could be validated.

OBJECTIVES

To record changes in ME pressure over a period of time in normal human ears, while the ET is kept closed.

SUBJECTS AND METHODS

On-line tympanometry was carried out in three subjects, who refrained from swallowing for 20-120 min.

RESULTS

During the time when the ET was kept closed by refraining from swallowing, tympanometric monotonous pressure decrease was recorded. Once the tested subject could not refrain from swallowing any longer and swallowed again, ME pressure equalized immediately.

[Fluorescence of the middle ear]

BACKGROUND

Discussions of the detection of fluorescein in the perilymph after intravenous (IV) administration have been contradictory. Differentiating between the fluorescence of mucosa and fluorescence signals of extravasation or perilymph fistulas seems to be rather difficult.

PATIENTS AND METHODS

We performed fluorescence endoscopy of the middle ear after IV administration of fluorescein, twice after intrathecal application, in 53 patients suffering functional cochleovestibular disturbances without improvement by infusion therapy or together with a tympanoplasty or tympanotomy. Endoscopic signs were documented in 40 patients.

RESULTS

Fluorescence of the eardrum in blue light was detected immediately (15-20 s) after IV injection of fluorescein. A maximum amount of mucosa fluorescence was found an average of 4 min later, decreasing up to 120 min (average 55 min). Fluorescence of the middle ear mucosa increased faster and lasted longer in ears with chronic otitis than in ears without signs of inflammation. Fluorescence signals of liquid in the round or oval niche were observed in 25 patients an average of 30 min after the IV administration. We documented these signals up to 240 min after administration, depending on the period between injection and start of the operation as well as the operating procedure. Probes of liquid >5 mul in the round niche could be sampled in three patients. These probes showed a significantly increased beta fraction in protein electrophoresis.

CONCLUSION

The choice of the right examination time point (45 min up to 2 h after IV administration) seems to be crucial for fluorescence endoscopy of the middle ear, as this method is a dynamic procedure.

Tympanic membrane vessel revisited: a study in an animal model

HYPOTHESIS

The present study aimed at elucidating whether there are blood vessels in the semitransparent portion of the tympanic membrane.

BACKGROUND

The normal semitransparent portions of pars tensa show strikingly few, small-caliber vessels under the otomicroscope. The major portion of a pars tensa seems to be devoid of blood vessels. In inflammatory conditions of the middle ear, the vascular pattern of the tympanic membrane is dramatically altered, and blood vessels traversing the pars tensa can be discernable.

METHODS

The study was performed in rats with healthy tympanic membranes and in tympanic membranes obtained from animals with purulent otitis media evoked by inoculation of Str. pneumoniae. The tympanic membrane vessels were dilated by injection of adenosin, and directly afterwards the animal was perfused with china ink. Vessels were also revealed by immunohistochemistry with antibodies for Thy-1 and the von Willebrand factor as well as by detection of carbon particles at an ultrastructural level.

RESULTS

Adenosin caused a marked dilation of the mallear and annular vessels. However, no preexisting vasculature was revealed in the normally transparent portions of the pars tensa except single vessels in the posterior quadrant and in the lower quadrants. In Str. pneumoniae-induced acute otitis media, the tympanic membrane thickened, bulged, and discolored. Even then, at 12 hours after inoculation, no vessels could be distinguished in the normally transparent portions of the tympanic membrane. However, at 4 and 7 days of acute purulent otitis media, vessels developed in those areas, most probably through ingrowth of newly formed vessels.

CONCLUSION

The results support the view that the semitransparent portions of the pars tensa lack vascularity. In inflammation, new vessels are formed in pars tensa to meet the demand for an increased blood supply.

Fluorescence findings of the facial nerve at decompression operation

Decompression operation was performed on patients with Bell's palsy and facial nerve palsy due to temporal bone fracture or otitis media, and a study was made on the relation between the fluorescence findings of the nerve and prognosis. The fluorescence of nerve was visible in 4 cases of Bell's palsy but none of the patients was completely cured, though the degree of cure tended to be proportional to the intensity of fluorescence. On the other hand, cure was seen even in cases of facial nerve palsy due to temporal bone fracture or otitis media that showed no fluorescence or any response in the maximal stimulation test (MST). It is suggested that Bell's palsy and facial nerve palsy due to trauma or otitis media do not share the same pathophysiology.

An endoscopic method of tympanic membrane fluorescein angiography

Fluorescein angiography is a recently developed method of studying the tympanic membrane's dynamic vasculature. Our preliminary studies using an ophthalmic fundus camera and aural speculum did not always permit visualization of the entire tympanic membrane, and the electronic flash unit used in our initial studies did not cycle fast enough to visualize effectively the rapid arterial phase of blood flow. In this report, we describe an endoscopic method of tympanic membrane fluorescein angiography that uses a continuous xenon light source. A representative angiogram from a normal subject is described. The mallear artery apparently is the major blood supply to the posterior half of the tympanic membrane, which is consistently better perfused than the anterior half. Branches from the annular ring of blood vessels supply the anterior half of the tympanic membrane. Preliminary studies of two temporalis fascia tympanoplasty patients indicate that the graft becomes revascularized 2 to 4 weeks after surgery and that posterior grafts may revascularize earlier than anterior grafts.

The vascular supply of the rat tympanic membrane

The vascular supply of the rat tympanic membrane (TM) was studied by means of otomicroscopy, angiography, acrylic casts, and light microscopy. The branches of the external carotid artery in the external auditory meatus were found to vascularize 1) the pars flaccida, 2) the manubrial part of the pars tensa, and 3) the junction between the fibrocartilaginous ring of the TM and the tympanic sulcus of the temporal bone. The TM vessels of areas 1 and 2 were found beneath the squamous epithelium, close to mast cells and nerve bundles. Vessels originating from the tympanic cavity (also probably emanating from the external carotid artery) supplied the periphery of the pars tensa with minute branches, localized immediately beneath the tympanal epithelium. The portion of the pars tensa between the manubrial part and the periphery lacked a vascular system. Upon mechanical stimulation (gentle pressure on the handle of the malleus), the normally visible vessels dilated and minute branches appeared. This dilation may be caused, at least partly, by a release of vasoactive substances from mast cells and/or nerves in its vicinity. Even under mechanical stimulation, a large portion of the pars tensa seemed to be devoid of vessels. The nutrition of this part may be served by diffusion, with nutrients originating from the vessels in the tympanal rim and along the handle of the malleus. The architecture of the attachment of the fibrocartilaginous ring to the bony sulcus of the temporal bone is quite unique. Thus, the flow in the dense vascular network between these structures may be affected by an altered tension in the pars tensa.

Pharmacological characterization of receptors on blood vessels in the tympanic membrane involved in otitis media

Acetylcholine dropped onto the meatal surface of the tympanic membrane evoked vasodilatation and a vascular leakage to the middle ear cavity. The vasoreactions were atropine-resistant. Substance P and vasoactive intestinal polypeptide (VIP) injected intravenously caused a marked vascular leakage and VIP also vasodilatation. These blood vessel changes seem to be regulated by the parasympathetic nerves as they were inhibited by vagotomy. Constriction of the tympanic membrane vessels was mediated through alpha-receptors.

Revascularization of fascia after tympanoplastic grafts. A study by fluorescein angiography

By means of a special method of fluorescein angiography the vascularization of free fascial grafts was studied after tympanoplasty. The individual phases of vascular ingrowth are documented. Changes in the vascular patterns during the follow-up study strongly suggest severe postoperative alterations in the transplant.