The effect of amphetamine sulfate injection on head and eye movements evoked by optokinetic stimulus was studied in squirrel monkeys. No change was found in the gain of optokinetic-oculomotor and optokinetic-caputomotor functions, even after the maximum dose (0.5 mg/kg) of amphetamine. Also, no change in eye-head coordination was found. However, amphetamine facilitated the frequency of head nystagmus, whereas that of eye nystagmus did not change. When the poststimulus responses were studied in the dark, both nystagmoid head movement and optokinetic after eye nystagmus showed first phase and second phase. A different effect was found in the duration of these two phases suggesting the existence of distinct generators. Moreover, the synchronized onsets of head and eye nystagmus in both phases, and synchronized occurrence of quick phases indicated the existence of shared neural circuitry between head and eye movements.

Using serially sectioned human temporal bones, endolymphatic volumes of utriculus and sacculus were measured with the aid of a computer. The mean of the utricular volume was 8.187 mm3, and the saccular volume, 2.096 mm3. The former was 3.9 X the latter. The surface area of the macula utriculi was 3.271 mm2, and the macula sacculi was 2.188 mm2. The former was 1.5 X the latter. The study using pathologic temporal bones (Meniere's disease, otosclerosis, and otitis media chronica) showed that the utricular volume could indeed increase, and the saccular membrane was found to be more fragile than the utricular membrane in those diseased conditions.

Head and eye movements induced by vestibular stimuli (rotational velocity steps) were studied under several experimental conditions in squirrel monkeys. Monkeys showed prominent head nystagmus under a free head condition. Slow phase gaze velocity (SPGV) was calculated by summing the slow phase speed of coupled head and eye nystagmus. A statistical test showed no significant difference between slow phase eye velocities in a fixed head versus SPGV in a free head condition. This indicates that an accurate negative feedback control of eye movements is performed by the vestibular system when sensing active head movements. Bilateral lateral semicircular canal block eliminated these responses in subjects without amphetamine injection. However, in amphetamine-injected animals, 14-21% of preoperative response could be found even after this operation. Since the plane of rotation was not parallel to that of the lateral semicircular canals, the result was considered to be due to vertical semicircular canal stimulation.

Eye and head nystagmus during horizontal optokinetic stimulation was analyzed in squirrel monkeys. Slow phase speed of coupled head and eye nystagmus showed highly significant negative correlations in normal subjects; correlation coefficients were -0.81 at 60 degrees/sec and -0.72 at 100 degree/sec stimuli. Bilateral semicircular canal block resulted in a reduction of the negative correlation. The postoperative reduction of the correlation coefficient value ranged from 0.17-0.28 (significant at P less than 0.01 level) at 60 degrees/sec stimulus and 0.06-0.13 (non significant) of 100 degrees/sec stimulus. Gaze speed was calculated by summing slow phase speeds of coupled head and eye nystagmus. Mean error of gaze in normal subjects was 1.5% at 60 degrees/sec stimulus and 7.8% at 100 degrees/sec stimulus. Mean gaze speed showed an overshoot (8% at 60 degrees/sec stimulus and 6.5% at 100 degrees/sec stimulus) in the tree to four weeks postoperative period; however, this subsided two to three months after the operation. Measurement of head-turning performance (in yaw plane) in humans may provide a clinically useful index for the assessment of certain types of vestibular function.

The slow phase eye velocity (SPEV) and duration of post-rotatory nystagmus (PRN) were studied in squirrel monkeys (Saimiri sciureus) after a ramp speed rotation (0-200 degrees/sec, with 1 degree/sec2 angular acceleration). When the results were compared between straight upright vertical rotation, 9 degrees tilt rotation, and 18 degrees tilt rotation, faster decay both in SPEV and in duration was found in the tilt rotation situations. Difference in nystagmic decay curves by tilting rotation axis could be from the convergence of macula-semicircular canal inputs. Subsequently bilateral macular ablation (two-stage) was performed. The difference in nystagmus decay curves between three different rotations was reduced; therefore, the change of gravity direction perceived through gravity receptors other than macular endorgans was minimal and did not produce a difference in three different rotations.

The degree of regeneration of nasal structures after surgical resection was evaluated in six mongrel dogs that underwent selective resection of the nasal bones and upper lateral cartilages. Preservation of the periosteal and periochondrial flaps was accomplished during the resection. In several cases, different tissues were interposed between the flaps before their closure. The dogs were killed at two-and eight-month intervals after the original resections. No evidence of new cartilage regeneration was found on microscopic evaluation in the region of the resected upper lateral cartilages. Minimal new bone foci were noted at the edge of the resected nasal bones in three of the cases. The findings failed to support any significant degree of nasal structure regeneration after resection.

Cartilage regeneration was histologically evaluated in vivo in the squirrel monkey pinnae. Only 2 of 11 ears exhibited evidence of cartilage regeneration (Movat stain) within the subperichondrial area, eight to nine weeks postoperatively. The present experimental results in squirrel monkeys contradict the previously reported high incidence of ear cartilage regeneration in young rabbits and may reflect a difference in surgical technique, animal species, or animal age.

When otitic cholesteatomas are removed by a surgical method that preserves or reconstructs the bony canal wall and tympanic membranes, there is a risk of imcomplete removal and possible regrowth of the lesion. To study the incidence of this complication, 52 patients with cholesteatoma had elective repeaated explorations at various postoperative intervals; eight (15.4%) had early cholesteatoma regrowth even though there was no clinical evidence of it. Seven of these regrowths were small and were again srugically removed. It is advocated that conservative surgery for cholesteatoma be followed up in two years by another elective surgical exploration to check for and dispose of possible cholesteatoma regrowth. This would provide safety comparable to that achieved with radical mastoidectomy, with far better function and hearing. The method does necessitate patient understanding and cooperation and I suggest methods of achieving this.

Using a damped pendular rotation table, which provided an oscillation of 15.5 sec, per-rotatory nystagmus, was evaluated in six squirrel monkeys that underwent unilateral labyrinthectomy and five that underwent unilateral lateral semicircular canal block, both pre- and postoperatively. The bidirectional summation of the nystagmic slow-phase eye speed after unilateral labyrinthectomy and after unilateral lateral semicircular canal block showed similar reduction to about 60 per cent of the values obtained in the pre-operative status. Under the present test situation, both slow-phase eye speed and number of nystagmic beats in the monkeys after unilateral lateral semicircular canal block were larger by the ampullopetal stimulation than those evoked by ampullofugal stimulation. The relation between slow-phase eye speed and number of beats showed similar tendency when we compared pre-operative controls and the group after unilateral lateral semicircular canal block, but the monkeys after unilateral labyrinthectomy depicted different tendencies.

Seventeen of eighteen squirrel monkeys, under a restrained condition, showed positional nystagmus in different body positions. Good repeatability and consistency of the nystagmus were found, especially at the left-lateral, right-lateral, and head-hanging positions. Positional nystagmus was not observed after the subject underwent bilateral labyrinthectomy. However, one subject in which part of the crista ampullaris posterior remained, continuously showed a positional nystagmus. Therefore, the existence of a minimal vestibular imput from the crista ampullaris could provoke the nystagmus. Some changes occurred in positional nystagmus after bilateral macular ablation; however, the nystagmus did not completely disappear. Even though imput from the crista ampullaris is essential to provoke positional nystagmus in squirrel monkeys, the positional nystagmus probably results from a central dyscoordination between vestibulo-oculomotor function, spino-oculomotor function, vestibular and brain circulation, and psychological condition.

After cerebellar uvulondulectomy in squirrel monkeys (Saimiri sciureus), a change occurred in the optokinetic nystagmus, in that there was a slow-phase eye speed decline, at the stimulus speeds above 90 degrees/sec. The difference was statistically significant when pre- and post-ablative comparisons were made. This result supports the usefulness of the optokinetic nystagmus examination to diagnose conditions which involve posterior inferior vermis of vestibulo-cerebellum. The optokinetic after-nystagmus depicted a similar decline postoperatively.

This study revealed that fractures of the bony nasal pyramid may heal by osteogenesis. Fibrous union and partial bone resorption may occur, especially where there is isolation of fragments by soft tissue. The nasal process of the maxilla was the most frequent site of such fibrous healing. Cartilaginous fractures healed by fibrous union in all cases.

Pendular rotation nystagmus was repeatedly investigated in squirrel monkeys after injecting Fentanyl in different doses. Good nystagmic in-hibition was observed although the slow phase eye movement remained after more than 0.027 mg/kg of the drug was administered. Sequential tests demonstrated the pattern of nystagmic suppression and its recovery along the post-injection time course.

Experimental destruction of vestibular labyrinthine epithelia of the guinea pig with cryosurgery indicates that, with three minutes of treatment with −180 C (−292 F) and the cryoprobe applied at a precooled state, there is virtually no damage visible with light microscopy. However, with electron microscopy, regular signs of impaired metabolism are observed a few hours after treatment due to destroyed intramitochondrial membranes and formation of vacuoles in the cytoplasm. With the cryoprobe applied at room temperature and slowly cooled down to −180 C (−292 F), there is after 2½ hours a marked disintegration of the epithelial lining, presumably due to complete blocking of the cellular metabolism and cracking of the cytoplasm into fragments by ice crystal formation. It was possible with cryosurgery to experimentally produce a selective destruction of semicircular canal cristae with utricle, saccule, and cochlea remaining intact.

AbstractEquilibrium disturbances may occur after neck lesions such as whiplash injuries. Abnormal proprioceptive inputs and vascular changes which involve not only the peripheral labyrinth, but also the brain stem are major factors producing these disturbances.Neck proprioceptor ablation was performed in healthy young adult squirrel monkeys by unilateral section of C1, C2 dorsal roots, or by injection of 1 cc of 1 percent Xylocaine® without epinephrine into the unilateral deep neck region.The dorsal root section was histologically confirmed by investigating spinal ganglion and adjacent nerve tissues. The Nauta stained spinal cord cross sections showed neuronal degeneration coming from the dorsal root.No spontaneous nystagmus was observed in the present series after section of the C1, C2 dorsal roots or Xylocaine® injection.After the Xylocaine® deep neck injection, the slow phase eye speed of optokinetic nystagmus declined in either direction in all animals. Slight decline of the quick component was also noticed. The wave form was also changed. The decline of slow phase eye speed partly represents the ablative effect of neck proprioceptors (joints, ligaments, and muscles), although the effect produced through other channels or by systemic toxicity cannot be eliminated. After the left C1, C2 dorsal root section, the slow phase eye speed declined only when there was clockwise stimulation. Statistical studies suggested significant differences between pre‐ and postoperative status. This finding suggested that the cervical input is connected to the oculo‐oculomotor pathway.Immediately after left C1, C2 dorsal root section, a reduction of the slow phase eye speed of postrotatory nystagmus occurred after counter‐clockwise rotation. The randomization test was used, and it was found that the postoperative scores are significantly lower than the pre‐operative scores.After the ablation of C1, C2 dorsal root, subjects failed to demonstrate any significant change in the pattern or numbers of pendular rotation nystagmic responses. On the other hand, three monkeys after Xylocaine® deep neck injection showed some change.The present experimental results indicate that the slow phase eye speed is a proper nystagmic parameter to study the neck proprioceptor contribution to oculomotor function.All animals after unilateral C1, C2 dorsal root section in the present series demonstrated moderate dysequilibrium (measured by the squirrel monkey rail test) confirming that neck injury can produce ataxia. There was no clear postoperative directional dominance of falls. For the diagnosis or investigation of the prognosis of many cervical disorders, bodily equilibrium examination is also important in addition to studying oculomotor function.

Acute experimentation with ultrasonic irradiation of the guinea pig labyrinth indicates that the physical effect of the ultrasonic irradiation such as agitation, cavitation and streaming are the prime factors in explaining damage to the sensory cells with ruptured cytoplasmic membranes, disappearance of ribosomes and mitochondria and formation of intracytoplasmic vacuoles which were found even one or two minutes after treatment. The basic pattern of degeneration is the same, whether the perilymphatic space is open or not. The thinner the bony shell remaining the shorter the exposure which can be used to achieve the same degree of destruction, thus minimizing heat transfer to the surrounding tissues. In the present acute experiments no cochlear damage was observed.

Anatomical studies on the nasal tip indicate four major areas of tip support: (1) the fibrous connection between upper and lower lateral cartilages; (2) the sesamoid complex extending the support of the lateral crus to the pyriform opening; (3) the ligamentous sling spanning between the paired domes of the lower lateral cartilages; and (4) the attachment of the feet of the medial crura to the posterior caudal septum. Routine rhinoplasty procedures compromise tip support predisposing to postoperative tip sagging (Pollybeak); however, tip rhinoplasty procedures can be modified to maintain tip support and projection by: high transfixion through the caudal cartilaginous septum confirming septal shortening to the anterior caudal septum, embricating the membranous septum over the anterior caudal septum, utilizing a cartilaginous strut, between and below the medial crura, or reestablishing the medial cruraposterior caudal septum anchorage.

In the surgical correction of protruding ears one should strive for normal-appearing and esthetically pleasing auricular contour and also to simplify surgical techniques so the residents and less experienced surgeons can also consistently achieve such end results. I describe an eclectic suture-only technique which achieves both goals. (A wrongly placed suture can be removed and replaced until it is in the right position without jeopardizing the final result. Conchal protrusion is corrected by suturing the lateral conchal wall to the mastoid periosteum via a low postauricular incision. If there is additional antihelix deformity, the skin is elevated on both sides of the antihelix; the lateral surface is gridded to weaken the cartilage spring. The antihelix is then correctly contoured with buried nonabsorbable mattress sutures tied posteriorly. The placement of these sutures is aided by external black silk guide sutures which are placed under direct vision while the ear is held in the corrected position.