Trochleaectomy: An Effective Treatment of Trochlear Pain in Monocular Patients

Background: Conventional treatment options for trochlear pain arising from trochleitis or primary trochlear headache include oral anti-inflammatory medications and/or local injection of corticosteroids and local anesthetic. Trochleaectomy is an additional option to consider for monocular patients with intractable trochlear pain. Methods: We report 3 patients undergoing trochleaectomy for refractory trochlear pain syndromes. Results: Trochleaectomy resulted in resolution of their periocular discomfort. Conclusions: Trochleaectomy is an effective procedure to treat trochlear pain syndrome in functionally monocular patients.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Trochleaectomy: An Effective Treatment of Trochlear Pain in Monocular Patients Pradeep Mettu, MD, Ronald Mancini, MD, Deborah I. Friedman, MD, MPH, James A. Garrity, MD Background: Conventional treatment options for trochlear pain arising from trochleitis or primary trochlear headache include oral anti-inflammatory medications and/or local injection of corticosteroids and local anesthetic. Trochleaectomy is an additional option to consider for monocular patients with intractable trochlear pain. Methods: We report 3 patients undergoing trochleaectomy for refractory trochlear pain syndromes. Results: Trochleaectomy resulted in resolution of their periocular discomfort. Conclusions: Trochleaectomy is an effective procedure to treat trochlear pain syndrome in functionally monocular patients. Journal of Neuro-Ophthalmology 2021;41:246–250 doi: 10.1097/WNO.0000000000000916 © 2020 by North American Neuro-Ophthalmology Society T he trochlea is a saddle-like structure located just inside the superomedial orbital rim (1). It functions like a pulley joint with a bursa and redirects the superior oblique muscle such that it can traverse posteriorly and laterally to insert onto the globe in a postequatorial fashion to depress, abduct, and intort the globe. Patients with complaints of pain in the trochlear area can present to a variety of specialists including ophthalmologists, neurologists, headache specialists, and primary care physicians underscoring the importance of understanding the possible underlying causes. The trochlea has been implicated in 2 distinct entities that may account for trochlear pain. Primary trochlear headache (PTH) is a recently recognized headache disorder Raleigh Eye and Face Plastic Surgery (PM), Raleigh, North Carolina; Departments of Ophthalmology (RM) and Neurology and Neurotherapeutics and Ophthalmology (DIF), University of Texas Southwestern Medical Center, Dallas, Texas; and Department of Ophthalmology (JAG), Mayo Clinic, Rochester, Minnesota. The authors report no conflicts of interest. Address correspondence to James A. Garrity, MD, Department of Ophthalmology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905; E-mail: [e-mail]. 246 that is diagnosed clinically (2). Often, patients have seen multiple providers before the diagnosis is reached, and the patient is adequately treated (3,4). Patients present either with periocular pain that is worsened by palpation of the affected trochlea or with pain around the trochlea worsened by eye movement. Ocular motility is unaffected, and imaging is negative (2). Treatment of PTH typically consists of local injections of corticosteroids and local anesthetics (2–4). In comparison, trochleitis is a secondary headache disorder caused by inflammation of the trochlea, which can either be isolated or associated with other forms of orbital inflammation. Some cases are idiopathic, and others are associated with systemic inflammatory conditions (4–6). The type of pain may be similar to PTH, but patients also have external signs of orbital inflammation, motility abnormalities, or abnormal orbital imaging depending on the extent of inflammation within the orbit. Trochleitis is treated with systemic anti-inflammatory medications including oral non-steroidal anti-inflammatory drugs or with local steroid injections (2,5–7). Patients with trochlear pain presenting to our practice (P.M. and J.A.G.) were described in a previous publication (3). An effective treatment approach is to provide local injections of a mixture of dexamethasone and 2% lidocaine just beneath the affected trochlea. In patients who also have tenderness over the supraorbital notch, an additional 0.25 mL of the same mixture may be injected separately beneath the supraorbital notch. Although the local injections are efficacious, in some patients, the duration of benefit is brief, and the return of pain can be debilitating. This often necessitates frequent return visits for treatment, which can be logistically challenging for many patients. We have recently encountered 3 patients with chronic trochlear pain who are functionally monocular. In the setting of monocular vision, the resultant ocular misalignment after trochleaectomy does not result in symptomatic diplopia. Given the unique circumstances, these patients underwent trochleaectomy as an attempt to definitively Mettu et al: J Neuro-Ophthalmol 2021; 41: 246-250 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution alleviate refractory trochlear pain. We describe our technique and our experience with this procedure. METHODS This is multi-institution case series. Patients undergoing trochleaectomy for trochlear pain syndrome were included. We describe their clinical characteristics, surgical techniques, and outcomes. RESULTS Case 1 A 39-year-old woman was evaluated for right trochlear pain in January 2016. The pain was worse with eye movements and alleviated by bending forward. It was present for the past 15 years with steady worsening, rated a 6 out of 10 in severity. The discomfort caused nocturnal awakening, presumably produced by rapid eye movement sleep. She had an extensive ocular history notable for intractable binocular diplopia despite numerous previous strabismus surgeries. She was sufficiently debilitated that she underwent placement of an opaque intraocular lens implant elsewhere in the left eye, rendering her functionally monocular. She had a history of loin pain hematuria syndrome for which she underwent a right nephrectomy for right kidney autotransplant (8). Additional medical problems included hypogammaglobulinemia, depression, anxiety, asthma, and chronic back, neck, and hip pain requiring injections. She had previously undergone an MRI head elsewhere in April 2013 for her headaches. There were no abnormalities of the trochleas, although orbital views were limited. The eye examination revealed discomfort on palpation of the supraorbital notches. For her bilateral trochlear pain, she underwent injections of 3 mg of dexamethasone (0.75 mL of dexamethasone 4 mg/mL) mixed with 0.25 mL of 2% lidocaine with epinephrine 1:100,000 (total volume of mixture is 1 mL) at each trochlea. She returned for followup 6 weeks later at the end of February 2016. The injection had made her pain-free on the right. On the left, pain improved from 6/10 to 2/10 after the injection. Over the preceding week, her symptoms returned. When re-examined, she was tender at each trochlear and supraorbital notch. She underwent repeat injections bilaterally this time to include the supraorbital notches. She returned every 6–8 weeks for repeat injections stating that each injection had made her pain-free but with gradual recurrence the week before being seen. In June 2016, she initiated a conversation regarding trochlear excision in an effort to definitively eradicate pain. Given her functionally monocular status, we planned left trochlear excision, which she underwent in July 2016 (Fig. 1). The surgical technique is described below. The area adjacent to the right trochlea was also reinjected while she was under anesthesia. Histopathologic examination demonstrated cartilage and skeletal muscle without diagnostic Mettu et al: J Neuro-Ophthalmol 2021; 41: 246-250 FIG. 1. Forceps indicate location of the trochlea from a subbrow incision approach. abnormality (Fig. 2). She returned 6 weeks later for her postoperative visit at which time she was pain-free on the right and left. On the left, she had a small area of numbness in a narrow band that extended to the hairline. She had minimal limitation of depression in adduction with the left eye. She expressed interest in pursuing a right trochlear excision. In September 2016, she underwent right trochlear excision, which was performed in a similar fashion. Once again, histopathologic examination showed fibrous cartilaginous tissue without any evidence of inflammation. When she returned in October 2016, there was no pain, but a left hypertropia was now present. On examination, there was no pain with palpation of the either superomedial orbit, although a 16-prism diopter left hypertropia was measured. When re-examined in March 2017, she reported recurrence of pain over the right supraorbital notch, and that the left hypertropia had progressed. There was no pain with palpation over either trochlea. She requested transection of the right supraorbital nerve. To improve her alignment, we offered left inferior oblique myectomy at the same time. To transect the right supraorbital nerve, we used a 1-cm incision over the right supraorbital notch. The arcus marginalis was opened just below the notch. The supraorbital nerve was identified and transected at the supraorbital notch. She was pain-free until March of 2018. At that time, she developed gradual recurrence of pain on the right. She underwent an orbital CT that did not show any abnormalities in either trochlear fossa. In May of 2018, she underwent re-excision in the area of the trochlea on the right. Pathology was consistent with a neuroma (Fig. 3). Based on the history and previous pathology, and the new pathological findings, the neuroma was consistent with postamputation pathological changes. The neuroma was likely not seen on preoperative computed tomography due to its small size. Postamputation neuromas are reactions to surgical trauma that lead to thickening in the nerve end. They can lead to pain that sometimes responds to surgical resection (9). In October 2018, she developed bilateral pain. Despite her previous excisions with pathology confirming 247 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution FIG. 2. Pathology from excised trochlea shows skeletal muscle (superior oblique) and fibrous tissue without inflammation (H&E ·100). FIG. 3. Pathology from re-excised trochlea shows giant cell reaction in the left lower quadrant with an adjacent neuroma (H&E ·40). sensory nerves having been removed, she had intact sensation on the right. During the same month, she underwent bilateral excisions in the area of the trochlea. Pathology showed neuromas on both sides. Her most recent follow-up was in January of 2019 at which time she was happy and pain-free. immediately after having an ipsilateral cataract extraction and intraocular lenses implantation. He had poor vision in that eye from a central retinal artery occlusion 1 year prior. He described aching and pressure-like pain, rated a 4 out of 10 in intensity, peaking to an 8–10 out of 10 in 5 minutes. At peak intensity, he felt like the eye was “blowing up,” triggering seizure-like episodes. During an acute attack, there was right eyelid ptosis and bilateral lacrimation, rhinorrhea, and aural fullness. Once an hour, he had similar episodes in which the pain peaked at a lower level, resolving over several minutes. The episodes awakened him from sleep and occurred at any time during the day or night. Although the “seizures” were evaluated and nonepileptic in nature, they precluded him from driving and engaging in many other activities that he had previously enjoyed. Visual acuity was hand motions at 5 feet in the right eye and 20/20 in the left eye. There was bilateral dermatochalasis and optic atrophy in the right eye. The right trochlea was tender to palpation. Contrastenhanced MR of the orbits was normal, and MRI of the brain showed a 2-mm · 3-mm paramedian pontine lesion consistent with a capillary telangiectasia. There was ageappropriate cerebral atrophy with subcortical white matter microvascular ischemic changes. He underwent a right greater occipital nerve block (4 mL of 0.75% bupivacaine) and right trochlear block (0.15 mL of 2% lidocaine without epinephrine and 1.5-mg dexamethasone 10 mg/mL) at his initial visit with complete pain relief in the office. Lamotrigine 25 mg was initiated and gradually increased to 200 mg daily for possible shortlasting unilateral neuralgiform attacks with minimal reduction in his pain level. He returned for monthly right greater occipital and trochlear blocks, which afforded him good relief for about 2 weeks each time. The patient repeatedly commented that he would rather have his right eye removed than endure the pain and seizures. Removal of the right trochlea was suggested and performed 5 months after the Case 2 A 27-year-old woman had been followed in our clinic since 2003 for a left optic nerve sheath meningioma (ONSM) with radiation and surgical resection previously performed elsewhere. Her medical history was otherwise negative. Visual acuity was 20/20 in the right eye and no light perception the left eye. In March 2013, she developed right trochlear pain. She described pain near the medial right brow that was constant and shooting, rated 8/10, and exacerbated by eye movement. The pain did not wake her up at night. Heat provided some relief; however, over the counter, pain relievers offered no benefit. Examination revealed tenderness over the right trochlea. She also had a left sensory exotropia. She underwent routine injections with of 1 mL total of the standard mixture of 3 mg of dexamethasone combined with 0.25 mL of 2% lidocaine with epinephrine 1:100,000. An orbital CT was performed in October 2015 for right orbit pain. The scan was unremarkable aside from postoperative changes related to her previously resected left ONSM. Given the need for frequent injections in the preceding years, in October 2016, we discussed excision of the right trochlea. She underwent excision of the right trochlea using the described technique. Histopathologic examination showed skeletal muscle, cartilage, and fibrous tissue without signs of inflammation. Per our telephone correspondence with her, she was doing well and was pain-free at 18 months after surgery. Case 3 A 77-year-old man developed pain in and around the right eye a year before his initial visit in April 2017, which started 248 Mettu et al: J Neuro-Ophthalmol 2021; 41: 246-250 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution initial visit. Pathology showed dense connective tissue without inflammation. The pain ceased immediately after surgery and the “seizures” stopped. He was seen 2 months after surgery and was doing well without diplopia. He then later developed superolateral periorbital pain that was different from the previous trochlear pain he experienced. The new pain was successfully treated with local injections. The patient was last seen in April 2019. He continues to have periorbital pain that responds to local injections, but the original trochlear pain that resolved after surgery has not recurred. Surgical Technique for Trochleaectomy Under general anesthesia, the proposed incision spanning approximately 1.5 cm is marked beneath the superomedial orbital rim. Alternatively, a medial upper eyelid crease incision can be used to obtain adequate exposure. The location of the supraorbital notch is also marked for reference. Local anesthetics consisting of 2% lidocaine with epinephrine 1:100,000 is injected along the superomedial orbital rim for hemostasis. The incision is carried down to the orbital rim, and the arcus marginalis is identified. Immediately posterior to the arcus marginalis, the trochlea and superior oblique tendon can be identified. The superior oblique tendon, temporal to the trochlea, can be isolated with a small muscle hook. The course of the tendon can then be traced, facilitating identification of the trochlea (Fig. 4). A periosteal elevator is then used to reflect the periosteum off of the bone anterior to the trochlea, and the trochlea is then excised. DISCUSSION Patients with headaches can be challenging diagnostically and therapeutically. Headache pain is subjective and can be functional further complicating management. It is important to consider PTH and trochleitis on the differential diagnosis of periocular pain. Postamputation neuromas are also a potential cause of periocular pain as seen in Case 1. Of note, none of our patients had pathology consistent with a primary neuroma. Although there may be pathophysiologic differences between PTH and trochleitis from a clinical standpoint, treatment seems to be equally effective. In our cases, there were no signs of inflammation on initial pathology. This suggests a diagnosis more consistent with PTH rather than a trochleitis diagnosis based on the data of Tychsen et al. Despite the lack of inflammation in PTH, local steroid treatments seem to be effective in treating this condition, although the therapeutic benefit is temporary, typically lasting weeks, and the therapeutic mechanism is uncertain. A placebo effect cannot be ruled out. Anecdotally, especially patients with long-standing severe pain and a first-time injection, the pain may worsen before improving. Ice packs to the trochlear area or consideration of another injection are options. Mettu et al: J Neuro-Ophthalmol 2021; 41: 246-250 FIG. 4. The superior oblique muscle, tendon, and trochlea are all demonstrated from a superomedial lid crease approach. In general, our preferred approach is to treat patients with trochlear pain (from both PTH and trochleitis) with our standard local injections of a mixture of 3 mg of dexamethasone and 0.25 mL of 2% lidocaine with epinephrine 1:100,000 (total of 1 mL) on an as-needed basis. Our preference is dexamethasone rather than the particulate steroid preparations such as triamcinolone both to address concerns of embolization and also skin changes. However, occasionally, such a monocular patient as described in this series may present, and trochleaectomy can be considered. Thus far, our surgical results have been promising with good therapeutic effect. The mechanism through which this surgical procedure alleviates pain is not clear and may not be solely due to the mechanical interruption of sensory nerves in the trochlear area. This is highlighted by the recurrence of pain in Case 1 despite pathological confirmation of the removal of sensory nerves. However, the recurrence of pain after surgical resection may be due to a postamputation neuroma, and additional resection may provide relief. The risk of symptomatic recurrent postamputation neuroma remains nonetheless. Our small experience indicates that this surgical approach may be successful in carefully selected cases of functionally monocular patients with intractable pain. Repeat excision can be helpful in the recurrence of pain. More cases and continued follow-up will help better characterize the effectiveness of trochleaectomy for refractory trochlear pain. STATEMENT OF AUTHORSHIP Category 1: a. conception and design: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini; b. acquisition of data: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini; c. analysis and interpretation of data: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini. Category 2: a. drafting the manuscript: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini; b. revising it for intellectual content: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini. Category 3: a. final approval of the completed manuscript: J. A. Garrity, P. Mettu, D. I. Friedman, and R. Mancini. 249 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution ACKNOWLEDGMENTS The clinical photographs were used with consent from the patients. The authors thank the pathologists involved in these cases, Diva Salomao, MD (Mayo Clinic), and R. Nick Hogan, MD, PhD (UT Southwestern), for their expertise and assistance in reviewing these cases. REFERENCES 1. Helveston EM, Merriam WW, Ellis FD, Shellhamer RH, Gosling CG. The trochlea. A study of the anatomy and physiology. Ophthalmology. 1982;89:124–133. 2. Yangüela J, Sánchez-del-Rio M, Bueno A, Espinosa A, Gili P, Lopez-Ferrando N, Barriga F, Nieto JC, Pareja JA. 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