Posterior semicircular canal nystagmus is conjugate and its axis is parallel to that of the canal.

A patient with a postoperative fistula of the left posterior semicircular canal is presented. Negative pressure in the external ear canal produced upbeat-torsional nystagmus, which was recorded in three dimensions using binocular scleral search coils. The nystagmus was conjugate, without skew deviation, and its trajectory corresponded to the anatomic axis of the left posterior canal. The current study helps validate Ewald's first law in humans: the axis of nystagmus should match the anatomic axis of the semicircular canal that generated it. This law is clinically useful in diagnosing pathology of the vestibular end-organ, such as benign paroxysmal positional vertigo or the superior semicircular canal dehiscence syndrome.

Evaluating the effects of oral prednisolone on recovery after tonsillectomy: a prospective, double-blind, randomized trial.

OBJECTIVES: To investigate the role of a 7-day course of oral prednisolone on recovery from tonsillectomy. STUDY DESIGN: Double-blind, randomized, placebo-controlled trial of 50 consecutive patients, aged 5 years and older, who had no previous or known contraindications to steroid therapy. METHODS: The patients were randomized at the time of surgery to either a 7-day course of daily placebo or prednisolone (dosage: 10 mg per day in patients aged 5-11 y, 0.5 mg/kg in those aged 12 and older). Age, sex, weight, diagnosis, tonsil size (in cm2), additional adenoidectomy, performing surgeon, method of dissection, length of procedure, total blood loss, intraoperative fluid requirement, and length of hospitalization were documented for each patient. During the first postoperative day, morning pain score, paracetamol use, oral fluid intake, temperature, presence of nausea and vomiting, level of activity (low, moderate, or normal), and type of diet (liquid, soft, or normal) were recorded. RESULTS: The steroid group consisted of a greater number of diathermy dissection cases and had significantly less intraoperative blood loss (P value = .022 and .017, respectively). On postoperative days 4 to 7, the steroid group experienced less nausea and vomiting (P value = .01, .04, .04, and .04, respectively). Paracetamol use was less in the steroid group on days 2, 7, and 8 (P value = .03, .02, and .02, respectively). There was no difference between the two groups for the other data measured. CONCLUSION: A 7-day course of corticosteroids may play a limited role in patients' recovery from tonsillectomy.

Posterior semicircular canal occlusion for intractable benign positional vertigo: outcome in 55 ears in 53 patients operated upon over 20 years.

OBJECTIVE: To report the outcome of posterior semicircular canal occlusion surgery for intractable benign positional vertigo, regarding vertigo cure rate and hearing and balance outcomes. METHODS: Retrospective review of 53 patients presenting with benign positional vertigo, unresponsive to repositioning manoeuvres, who eventually underwent posterior canal occlusion, over a 20 year period. RESULTS: From 1991 to 2011, 5364 benign positional vertigo patients were treated in our balance disorders clinic; 53 of those who failed to respond to repositioning underwent posterior canal occlusion. All 53 were cured of their benign positional vertigo. Nine suffered some symptomatic permanent hearing loss (>20 dB at low and >25 dB at high frequencies). Ten patients suffered caloric vestibular function deterioration, with mild but permanent subjective imbalance in five; a further 10 patients with no post-operative caloric test changes also had some permanent imbalance. Benign positional vertigo later developed in the operated ear lateral canal in two patients and in the opposite ear posterior canal in eight patients. Two patients needed bilateral sequential posterior canal occlusion. CONCLUSION: Posterior canal occlusion is a highly effective treatment for intractable benign positional vertigo, with what is probably an acceptable risk to hearing and balance: five of six patients will have no hearing problem and nine of 10 no balance problem after surgery.

Obstructive sleep apnoea due to a dermoid cyst of the floor of the mouth.

A case of obstructive sleep apnoea is reported that was caused by a dermoid cyst of the floor of the mouth and cured by surgery.

Compensation of the human vertical vestibulo-ocular reflex following occlusion of one vertical semicircular canal is incomplete.

The vestibulo-ocular reflex (VOR) was studied in nine human subjects 2-15 months after permanent surgical occlusion of one posterior semicircular canal. The stimuli used were rapid, passive, unpredictable, low-amplitude (10-20 degrees), high-acceleration (3000-4000 degrees/s2) head rotations in pitch and yaw planes. The responses measured were vertical and horizontal eye rotations, and the results were compared with those from 19 normal subjects. After unilateral occlusion of the posterior semicircular canal, the gain of the head-up pitch vertical VOR--the vertical VOR generated by excitation from only one and disfacilitation from two vertical semicircular canals--was reduced to 0.61 +/- 0.06 (normal 0.92 +/- 0.06) at a head velocity of 200 degrees/s. In contrast the gain of the head-down pitch vertical VOR--the VOR still generated by excitation from two, but disfacilitation from only one vertical semicircular canal--was within normal limits: 0.86 +/- 0.11 (normal 0.96 +/- 0.04). The gain of the horizontal VOR in response to yaw head rotations--ipsilesion 0.81 +/- 0.06 (normal 0.88 +/- 0.05) and contralesion 0.80 +/- 0.11 (normal 0.92 +/- 0.11)--was within normal limits in both directions (group means +/- two-tailed 95% confidence intervals given in each case). These results show that occlusion of just one vertical semicircular canal produces a permanent deficit of about 30% in the vertical VOR gain in response to rapid pitch head rotations in the excitatory direction of the occluded canal. This observation indicates that, in response to a stimulus in the higher dynamic range, compensation of the human VOR for the loss of excitatory input from even one vertical semicircular canal is incomplete.

The effect of unilateral posterior semicircular canal inactivation on the human vestibulo-ocular reflex.

The responses to rapid, passive, unpredictable, low amplitude (10-20 degrees), high acceleration (3,000-4,000 degrees/s2) head rotations were used to study the human vestibulo-ocular reflex (VOR) in pitch and yaw plane after unilateral posterior semicircular canal occlusion (uPCO) in 10 subjects. The results from these 10 uPCO subjects were compared with those from 18 normal subjects. The VOR gains at a head velocity of 200 degrees/s in the uPCO subjects were: pitch upward = 0.62 +/- 0.06, pitch downward = 0.87 +/- 0.11, yew ipsilesion = 0.78 +/- 0.06, yaw contralesion = 0.79 +/- 0.10 and in normal subjects were: pitch upward = 0.92 +/- 0.06, pitch downward = 0.96 +/- 0.04, yaw right = 0.88 +/- 0.05, yaw left = 0.91 +/- 0.12 (group means +/- twotailed 95% confidence intervals). The results showed that the pitch-vVOR gain was significantly (p < 0.05) decreased in response to upward head impulses whereas in response to downward, ipsilesion and contralesion head impulses were not significantly different (p > 0.05) from the normals. This study shows that there is 30% permanent residual deficit of the upward pitch-vVOR with an up-down asymmetry in pitch-vVOR gain following inactivation of a single posterior semicircular canal and that compensation of pitch-vVOR function is incomplete.