[Diagnosis and treatment of trochlear nerve palsy]

Compressive lesions of the head and neck: Common and uncommon must-know entities

There are many lesions that cause compression of nerves and vessels in the head and neck, and they can often be overlooked in the absence of adequate history or if not suspected by the radiologist. Many of these lesions require a high index of suspicion and optimal positioning for imaging. While a multimodality approach is critical in the evaluation of compressive lesions, an MRI utilizing high-resolution (heavily weighted) T2-weighted sequence is extremely useful as a starting point. In this review, we aim to discuss the radiological features of the common and uncommon compressive lesions of the head and neck which are broadly categorized into vascular, osseous, and miscellaneous etiologies.

Surgical outcomes for unilateral superior oblique palsy in Chinese population: a retrospective study

AIM

To evaluate the outcome after surgery for unilateral superior oblique (SO) palsy in Chinese.

METHODS

The medical records of 39 patients that underwent surgery for unilateral SO palsy between January 2003 and December 2012 at Caritas Medical Centre, Hong Kong, were retrospectively reviewed. All surgeries were performed by a single surgeon. Pre-operative assessments for vertical deviation, cyclo-deviation, and Knapp's classification were obtained to determine the nature and degree of surgical correction. Vertical deviation was measured at 1wk; 1, 6mo and on last follow-up day post-operatively. Cyclo-deviation was measured on last follow-up day post-operatively.

RESULTS

During the 10y period, 39 subjects were recruited. The most common etiology was congenital (94.9%). Knapp's Type III (66.7%) and Type I (12.8%) classifications were the most common subtypes. To treat SO palsy, the most common surgical procedures were: isolated inferior oblique (IO) anteriorization (41.0%), isolated IO myectomy (10.3%), and isolated IO recession (10.3%). At 3.5±2.1y post-operatively, the vertical deviation was significantly reduced (15.1±6.2 PD versus 0.5±1.4 PD, P<0.0001) without significant improvement in cyclo-deviation (P=0.5). Initial vertical deviation was correlated with cyclo-torsion (r=0.4, P=0.007). Those with over-correction had greater initial vertical deviation (19.4±7.2 PD versus 13.2±4.3 PD, P=0.003). After a single operation, 84.6% of subjects achieved a vertical deviation within ±3 PD.

CONCLUSION

The majority of subjects achieved corrected vertical deviation after a single surgery although there was no improvement in cyclo-deviation. Those with over-correction of primary position deviation had greater preoperative vertical deviation and it may be related to simultaneous multiple muscle surgery.

Ocular complications after posterior superior alveolar nerve block: a case of trochlear nerve palsy

Many intraoperative complications occurring during third molar surgery are described in the literature. Unilateral trochlear nerve palsy secondary to dental anaesthesia is a rare complication. We report the case of a 36-year-old healthy man, ASA I classification, requiring upper third molar extraction. Articaine 1:200,000 epinephrine for right posterior superior alveolar (PSA) nerve block was administered locally in the mucobuccal fold above the upper third molar. A few minutes after PSA nerve block the patient experienced double-vision. The patient was subsequently visited by an ophthalmologist and the condition was diagnosed as transient unilateral vertical diplopia due to temporary paralysis of the superior oblique muscle as a result of the anaesthetic solution involving the IV cranial nerve. The authors report this unusual case and discuss the possible anatomical pathways that might explain this rare phenomenon.

Superior rectus muscle recession for residual head tilt after inferior oblique muscle weakening in superior oblique palsy

Purpose

Residual head tilt has been reported in patients with superior oblique muscle palsy (SOP) after surgery to weaken the inferior oblique (IO) muscle. The treatments for these patients have not received appropriate attention. In this study, we evaluated the superior rectus (SR) muscle recession as a surgical treatment.

Methods

The medical records of 12 patients with SOP were retrospectively reviewed. Each of these patients had unilateral SR muscle recession for residual head tilt after IO muscle weakening due to SOP. The residual torticollis was classified into three groups on the basis of severity: mild, moderate, or severe. Both IO muscle overaction and vertical deviation, features of SOP, were evaluated in all patients. The severity of the preoperative and postoperative torticollis and vertical deviation were compared using a paired t-test and Fisher's exact test.

Results

The torticollis improved in nine of 12 (75%) patients after SR muscle recession. The difference between the preoperative and postoperative severity of torticollis was statistically significant (p = 0.0008). After surgery, the mean vertical deviation was significantly reduced from 12.4 prism diopters to 1.3 prism diopters (p = 0.0003).

Conclusions

Unilateral SR muscle recession is an effective method to correct residual head tilt after IO muscle weakening in patients with SOP. This surgical procedure is believed to decrease head tilt by reducing the vertical deviation and thereby the compensatory head tilt.