Expression of hyperpolarization-activated current (Ih) in zonally defined vestibular calyx terminals of the crista

Calyx terminals make afferent synapses with type I hair cells in vestibular epithelia and express diverse ionic conductances that influence action potential generation and discharge regularity in vestibular afferent neurons. Here we investigated the expression of hyperpolarization-activated current (Ih) in calyx terminals in central and peripheral zones of mature gerbil crista slices, using whole cell patch-clamp recordings. Slowly activating Ih was present in >80% calyces tested in both zones. Peak Ih and half-activation voltages were not significantly different; however, Ih activated with a faster time course in peripheral compared with central zone calyces. Calyx Ih in both zones was blocked by 4-(N-ethyl-N-phenylamino)-1,2-dimethyl-6-(methylamino) pyrimidinium chloride (ZD7288; 100 µM), and the resting membrane potential became more hyperpolarized. In the presence of dibutyryl-cAMP (dB-cAMP), peak Ih was increased, activation kinetics became faster, and the voltage of half-activation was more depolarized compared with control calyces. In current clamp, calyces from both zones showed three different categories of firing: spontaneous firing, phasic firing where a single action potential was evoked after a hyperpolarizing pulse, or a single evoked action potential followed by membrane potential oscillations. In the absence of Ih, the latency to peak of the action potential increased; Ih produces a small depolarizing current that facilitates firing by driving the membrane potential closer to threshold. Immunostaining showed the expression of HCN2 subunits in calyx terminals. We conclude that Ih is found in calyx terminals across the crista and could influence conventional and novel forms of synaptic transmission at the type I hair cell-calyx synapse.NEW & NOTEWORTHY Calyx afferent terminals make synapses with vestibular hair cells and express diverse conductances that impact action potential firing in vestibular primary afferents. Conventional and nonconventional synaptic transmission modes are influenced by hyperpolarization-activated current (Ih), but regional differences were previously unexplored. We show that Ih is present in both central and peripheral calyces of the mammalian crista. Ih produces a small depolarizing resting current that facilitates firing by driving the membrane potential closer to threshold.

[Hypertrophic eyelid conjunctival scar. A tarsal keloid]

The clinicopathologic case of a 53-year-old female patient with an abnormal tumor growing on the mucous part of the superior right eyelid is reported. The patient was operated on for ten years ago and a whitish mass slowly developed on the conjunctival face of the eyelid disturbing the use of corneal lenses. It was hard, painless and had the shape of a flat mushroom. The removal was performed under local anesthesia and allowed us to resect a hard and fibrous lesion. Histopathology showed that the lesion was made of a fibrous tissue organized like a hypertrophic scar. Surgical treatment of chalazion is frequent and rarely gives rise to abnormal scarring.

[Nevus mimicking a basal cell carcinoma of the eyelid]

A clinicopathologic case of a 41-year-old female patient exhibited a single cutaneous tumor at the inner part of the free margin of the inferior left eyelid. It was a pink, fleshy, and nodular well-circumscribed exophytic mass with thin vessels on its surface. Experienced already for 20 years, this lesion had been observed 6 years before and has not exhibited much change since then. However, its clinical appearance argued for a possible small basal cell carcinoma, which had grown over the inferior left lachrymal duct. After surgical removal, histopathology showed that the tumor was an amelanotic dermal nevus. No disturbance of lachrymal drainage was observed after surgery. This case shows that nodular amelanotic tumors of the eyelid, even when located on the inner segment of the eyelid, may be a nevus.

[Large basal cell carcinoma of the external palpebral angle]

A clinicopathologic case of an 89-year-old female patient with a single cutaneous tumor at the outer part of the outer left eyelids is reported. It was a pink nodular mass, well circumscribed, exophytic and with thin vessels. After surgical removal, histopathology showed that the tumor was a typical basal cell carcinoma, with many cystic-like cavities. Basal cell carcinomas can be commonly observed on the eyelids and surgical excision of these small size lesions is an easy way to perform a curative treatment. As often in other tumors, early diagnosis is probably the easiest way to improve the prognosis.

[Meibomian adenocarcinoma of the free palpebral edge. Report of a case]

A case of meibomian carcinoma of the left eyelid is reported in a 72-year-old female patient. The tumor had been present on the left eyelid for months. Clinically, the tumor appeared as a reddish mass implanted on the external part of the free margin of the left superior eyelid. An excisional biopsy disclosed meibomian carcinoma. A total resection of the left superior eyelid was followed by plastic surgery. Results after a one-month follow-up were very satisfactory. This case is emphasizes the importance of an early diagnosis which enabled us to perform a rather conservative treatment limited to the removal of the affected eyelid. The diagnosis of meibomian carcinoma is infrequent but it must be kept in mind in cases of tumor without the typical clinical characteristics of a basal cell or squamous cell carcinoma. Complete removal surgery may bring a curative effect and histopathology has a key role in the diagnosis of meibomian carcinoma.

[Limbal dermoid and Goldenhar syndrome. Report of an anatomoclinical study]

Dysembryoplastic neoplasm, the limbal dermoid is a benign congenital tumor involving the outer coat of the eye. This congenital tumor affected the right eye of a 6-year-old girl. The lesion was typically hemispheric, covered with pink skin, located in the inferior and temporal part of the cornea, and devoid of any major consequences except the cosmetic appearance of the eye. There were no other major abnormalities in the clinical examination but a single skin tag could be observed at the homolateral preauricular area without any visible cutaneous fistula next to it. This additional change allowed us to establish the diagnosis of a minor form of Goldenhar syndrome. This malformative syndrome typically includes several changes: dermoid and/or dermolipoma, preauricular tags and/or cutaneous fistulas in the same area, vertebral abnormalities etc. These findings may be limited to dermoid and cutaneous tags, as in our report. Such changes must be looked for in all limbal dermoids.

[Hyperkeratosis papilloma of the eyelid. An anatomic clinical case]

A clinicopathologic case of an 80-year-old male patient with a single cutaneous tumor on the upper part of the left eyelid is reported. It was a grayish and pigmented mass covered with a thick keratin layer, well circumscribed, and exophytic. After surgical removal, histopathology showed that the tumor had a papillomatous pattern and was growing under a thick layer of hyperkeratosis. It was a typical squamous cell papilloma. This tumor belongs to the benign eyelid tumor group and can be found on the eyelids of elderly people.

[Conjunctival in situ carcinoma in a patient with Waldenström's disease]

A 73-year-old male patient was treated for conjunctival in situ carcinoma invading the cornea of his right eye. The patient had been previously operated on for two corneoconjunctival lesions on the same eye (one was a pterygium, the other was simple epithelial hyperplasia) and was regularly followed for a systemic lymphoplasmocytic lymphoma (Waldenström's disease). After a corneoconjunctival excision of the tumor, the histological analysis was performed and established the diagnosis of in situ carcinoma. The tumor recurred a few months later and radiation therapy was then given. No recurrence was observed after this latter treatment.

Incidence and sequelae of nocturnal respiratory obstruction following posterior pharyngeal flap operation

A competent velopharyngeal mechanism is important for the production of normal speech, and the secondary procedure of a posterior pharyngeal flap (PPF) may be necessary in some patients to achieve this goal. A number of complications have been described in the literature following pharyngeal flap surgery. The purpose of this study was to examine short- and long-term complications after PPF surgery, and in particular the incidence and the end effect of nocturnal respiratory obstruction (NRO). All PPFs over a 17-year period performed at one institution and by the same surgeon were examined retrospectively. All medical records from the Commission of Handicapped Children of patients who had a PPF were reviewed. Patients with NRO were identified clinically, and sleep studies were administered with two or more of the clinical triad. During a 17-year period, 111 patients underwent a PPF to treat velopharyngeal incompetence. Twelve patients were identified with a syndromic association in addition to a clefting disorder, of which most (N = 9) consisted of Pierre Robin syndrome. The median age at PPF performance was 6.0 years and the average follow-up was 7.4 years. The early postoperative complication rate was 10%, including a 7.2% incidence of respiratory obstruction and 0.9% postoperative bleeding. Twenty-one patients (19%) had late complications or unsatisfactory results. Twelve patients (10.5%) developed NRO, and patients with Pierre Robin syndrome were particularly prone-4 of 9 patients developed this complication. Nine of 12 patients with NRO had sleep studies performed with a minimum interval of 6 months postoperatively. Eight of the nine studies were normal. Of the NRO group, 3 patients had takedown of their PPF, including the patient with an abnormal sleep study. All 3 patients improved markedly and none developed recurrence of velopharyngeal insufficiency. NRO is not an uncommon finding in PPF patients, but NRO does not necessarily imply the presence of obstructive sleep apnea. The consequences of persistent NRO over the long term deserve further study.