Abducens ocular neuromyotonia in a patient with nasopharyngeal carcinoma following concurrent chemoradiotherapy

Ocular neuromyotonia: an unusual case after radiotheraphy for nasopharyngeal carcinoma

Ocular neuromyotonia (ONM) is an infrequent disorder characterised by recurrent episodes of binocular diplopia caused by paroxysmal contraction of one or several extraocular muscles innervated by the same cranial nerve. It can be triggered spontaneously or caused by prolonged contraction of specific eye muscle(s) and is usually related to a local intracranial radiotherapy antecedent. We report the case of a 46-year-old woman who developed intermittent episodes of binocular diplopia eight years after radiotherapy for a nasopharyngeal carcinoma. After a complete neuro-ophthalmic assessment we diagnosed the case as an abducens nerve neuromyotonia. Although it is infrequent, radiotherapy to the nasopharynx is a possible cause of ONM, due to the proximity to the base of the skull and extraocular motor nerve pathways, especially that of the VI cranial nerve, as is the case presented in this article, about a patient whose history is a nasopharyngeal carcinoma treated with local radiotherapy.

The predictive value of serum lipids for eye metastases in male nasopharyngeal carcinoma patients

Background: Nasopharyngeal carcinoma (NPC) is a tumor that is commonly found in southern China. NPC has several risk factors, such as infection with the Epstein–Barr virus. However, we know little about the risk factors for eye metastasis (EM) in male patients with NPC. Serum lipids are well recognized as risk factors for cardiovascular disease, and recent studies show that they also have a relationship with the development of NPC.

Purpose: We designed the present study to determine whether they were relevant with the development of EM in male NPC patients by detecting the levels of several serum lipids.

Methods: A total of 1140 male patients with NPC were enrolled in this retrospective study and we divided them into two groups: the metastasis (EM) group and non-eye metastasis (NEM) group. A variety of serum lipids between the two groups were tested and compared.

Results: There were statistical differences in the levels of serum TG and TC between these two groups. Binary logistic regression showed that TG and TC were independent risk factors for EM in male NPC patients with P=0.004 and P<0.001, respectively. The area under the curve of TG and TC were 0.764 and 0.681, respectively, using cutoff values of 0.975 and 3.425 mmol/l, respectively. We found that TG had higher sensitivity and specificity values with 87.5% and 62.7%, respectively, than TC which were 50.0% and 87.2%.

Conclusion: TG and TC are potential risk factors for eye metastases in male NPC patients.

Surgery option in the management of delayed diplopia after radiation therapy for nasopharyngeal carcinoma

PURPOSE

Radiation therapy is a standard treatment for nasopharyngeal carcinoma. Diplopia due to radiation damage to the sixth nerve significantly erodes the patient's quality of life. This study investigated the effectiveness of extraocular surgery in the treatment of delayed diplopia caused by radiation therapy.

METHODS

A retrospective case series of 16 patients (7 men and 9 women) with delayed diplopia after radiation therapy for nasopharyngeal carcinoma was enrolled in the study. Unilateral lateral rectus resection was performed under topical anesthesia. Follow-up time was more than 12 months. Outcome measures were prism diopter and self-reported symptoms.

RESULTS

All patients diagnosed with sixth nerve palsy reported elimination of symptoms on postoperative day 1 without complications. One patient required a second procedure due to recurrence of symptoms. At 12-month follow-up, no patient reported recurrence of symptoms. The absolute horizontal deviation significantly decreased from a preoperative value of 16 prism diopter to a value of 1.5 prism diopter postoperatively (p < 0.001).

CONCLUSION

These results suggest that unilateral lateral rectus resection under topical anesthesia is an effective treatment for delayed diplopia after radiation therapy for nasopharyngeal carcinoma. A large randomized prospective study to confirm these findings is warranted.

Metastatic Papillary Thyroid Carcinoma Presenting as Abducens Palsy Complicated by Ocular Neuromyotonia

Papillary thyroid carcinoma (PTC) is a type of well-differentiated thyroid cancer that accounts for the majority of thyroid malignancies. The prognosis of PTC is very good and distant metastases are rare, especially to the skull base. The authors report the case of a 47-year-old woman with biopsy-proven PTC treated with surgery and radiation therapy who presented with headache and diplopia after 5 years and was found to have clivus and cavernous sinus metastasis. Following radiation therapy for her skull base and cavernous sinus lesion, she subsequently developed sixth nerve ocular neuromyotonia. Possible causes and treatments are reviewed.

Strabismus Surgery in Patients With Ocular Neuromyotonia: Potential Unmasking of the Condition and Effective Management Tool

BACKGROUND

Ocular neuromyotonia (ONM) is a rare motility disorder in which paroxysms of tonic extraocular muscle contraction from abnormal ocular motor nerve firing result in episodic diplopia and strabismus. Medical therapy with membrane-stabilizing agents has varied success. A surgical approach to treatment has not yet been described. We report the outcomes of strabismus surgery in patients with ONM.

METHODS

We describe 3 patients with sixth nerve paresis and ONM of the affected lateral rectus muscle who underwent strabismus surgery. All patients had a history of radiation therapy for intracranial tumors. Ophthalmologic and orthoptic examinations were performed with appropriate medical and neuroradiologic evaluation. Preoperative and postoperative data are presented and analyzed.

RESULTS

Two patients were noted to have ONM after their first strabismus surgery for a sixth nerve palsy. Patients 1 and 2 had 3 surgeries, whereas Patient 3 had 1 operation. Extraocular muscles operated on included the medial rectus and lateral rectus. Preoperative primary gaze baseline esotropia ranged from 35 to 75 prism diopters (Δ). All patients achieved improvement in ocular alignment and motility. Postoperative primary gaze deviations ranged from orthotropia to 20Δ of esotropia. Abduction deficits were unchanged or improved. The follow-up period ranged from 15 months to 2 years.

CONCLUSIONS

Patients with ONM of a paretic rectus muscle can achieve binocular fusion with strabismus surgery. ONM may manifest postoperatively in patients with a sixth nerve palsy and a contractured medial rectus who, preoperatively, were not noted to have ONM.

Abducens ocular neuromyotonia as a delayed complication of oropharyngeal carcinoma treated with radiation

BACKGROUND

Ocular neuromyotonia (ONM) is a disorder characterized by periodic involuntary extraocular muscle contraction that occurs almost exclusively in the setting of prior radiation to the sella or skull base. We present the first case of abducens neuromyotonia associated with oropharyngeal carcinoma.

METHODS AND RESULTS

We report a case of a 63-year-old patient with abducens ONM occurring 16 years after radiation treatment for oropharyngeal squamous cell carcinoma. A literature review was performed using Medline and PubMed databases to search for all documented cases of abducens neuromyotonia. Our review found 20 cases of abducens neuromyotonia but none after radiotherapy (RT) to the oropharynx.

CONCLUSION

Abducens ONM can occur because of disease at anatomic locations remote from the course of the sixth cranial nerve, most likely because of the irradiated area exceeding the intended field. Our case also supports the fact that RT can significantly precede symptom onset. © 2016 Wiley Periodicals, Inc. Head Neck 38: E2428-E2431, 2016.

Novel case of ocular neuromyotonia associated with thyroid-related orbitopathy and literature review

PURPOSE

To present a novel case of pupillary involvement in ocular neuromyotonia (ONM), a rare ocular syndrome that causes intermittent diplopia because of an abnormal delay in extraocular muscle relaxation and to conduct a literature review.

METHODS

A case report is presented to demonstrate clinical characteristics and treatment of ONM. In addition, a literature review is conducted by searching Medline and Embase databases. Data are collected from all known published cases listed in these databases to collate patient demographic data, presumed etiology or associated pathologies, and treatment strategies.

RESULTS

The presented case demonstrates successful carbamazepine treatment of thyroid-related orbitopathy-associated ONM involving cranial nerve III. A review of the literature elicits 66 published cases of ONM, three of which were deemed to be associated with thyroid-related orbitopathy. The most common cause of reported ONM is suprasellar pathology, comprising approximately 60% of documented cases. Most published ONM cases (n = 41) were treated with carbamazepine, demonstrating a success rate of 87.8%. Of the published cases, cranial nerve III was involved 56% of the time, cranial nerve VI was affected in 39% of cases, and only 9% of ONM cases involved cranial nerve IV.

CONCLUSIONS

Ocular neuromyotonia is a rare cause of intermittent diplopia. Unlike most neurologic etiologies of diplopia, this syndrome can often be treated effectively with carbamazepine by stabilizing the neural cell membrane. To the authors' knowledge, this is the first presentation of ONM associated with thyroid-related orbitopathy, demonstrating bilateral but asymmetric miosis during episodes of muscle spasm.