Superior oblique and inferior rectus muscle injury following frontal and intranasal sinus surgery

[Brown's syndrome]

Brown's syndrome is related to an abnormality of the superior oblique muscle: it is manifested by an oculomotor disorder with active and passive limitation of elevation in adduction, the field of action of the inferior oblique muscle. The origin is congenital or acquired secondary to multiple causes - inflammatory-infectious, traumatic or iatrogenic. The clinical and paraclinical signs are suggestive. Cerebral and orbital imaging including CT and magnetic resonance imaging (MRI) is essential for the diagnosis and management of congenital or acquired Brown's syndrome. The course may yield improvement (spontaneous or after etiological treatment) or a steady state. Treatment is rarely surgical. The indication for surgery requires specific functional and clinical signs: torticollis, hypotropia in primary position, associated strabismus and impaired binocular vision; the long-term results of the various surgical techniques are variable.

Extraocular Muscle Damage Associated with Endoscopic Sinus Surgery: An Ophthalmology Perspective

Background

Orbital complications associated with endoscopic sinus surgery are well documented. Damage to the medial rectus muscle results in complicated strabismus and disturbing diplopia. The aim of this study was to characterize the types of extraocular muscle injury and the number of muscles involved that may complicate endoscopic sinus surgery and correlate its occurrence to factors in the surgical procedure itself.

Methods

A retrospective chart review was performed of 14 patients with strabismus after endoscopic sinus surgery. Operative notes of the surgical procedure, pathology reports of the intraoperative specimens, postoperative pattern of strabismus, the extraocular muscle involved, and the type of muscle injury characterized by orbital imaging were reviewed in each patient.

Results

In our series, not only the medial rectus muscle but also the inferior rectus and the superior oblique muscles were damaged with multiple muscles being involved in one patient. Extraocular muscle injury varied from hematoma, entrapment of muscle in the fractured orbital wall, damage to the oculomotor nerve entry zone, muscle transection, and partial or complete muscle destruction with entrapment in scar tissue. Use of the microdebrider causes extensive irreparable muscle damage.

Conclusion

Extraocular muscle damage complicating endoscopic sinus surgery can produce therapeutically challenging complicated strabismus.

Anatomic relationship of the first olfactory neuron and trochlea: cadaveric study with surgical implications

BACKGROUND

Iatrogenic injury to the trochlea is a potential complication of the Draf III or endoscopic modified Lothrop procedure; however, the location of the trochlea from within the sinus cavity has yet to be clearly characterized. We performed the first cadaveric study assessing the position of the trochlea in relation to the first olfactory neuron, a commonly identified landmark during the Draf III procedure.

METHODS

Thirteen external dissections of the trochlea were performed on 7 disarticulated cadaveric heads via an extended Lynch type incision. An endoscopic Draf III procedure was then performed on all cadavers. A burr hole was then created at the trochlear fovea. A straight vector between the trochlear attachment and the ipsilateral first olfactory neuron was then created. The vector was then viewed from within the sinuses using a 30-degree endoscope. The endoscope was maneuvered to create an upright midline view centered on the olfactory neurons. An image was subsequently captured and analyzed using ImageJ software to calculate a vector angle. The linear distance between the 2 structures was also recorded.

RESULTS

Relative to the first olfactory neuron, the trochlea was found to be 19.52 ± 4.68 mm away and at an angle of 39.42 ± 8.54 degrees in the anterolateral, superior direction along the frontal bone.

CONCLUSION

We report the first anatomical dissection characterizing the position of the trochlea relative to the ipsilateral first olfactory neuron. Intraoperative recognition of this relationship during Draf III procedures can prevent potential injury to the trochlea.

Combined Brown syndrome and superior oblique palsy without a trochlear nerve: case report

Background

Congenital Brown syndrome is characterized by limited elevation particularly during adduction. The pathogenesis of congenital Brown syndrome is still controversial.

Case presentation

A 6-year-old boy had been tilting his head to the left since infancy. He showed right hypertropia (RHT) of 2 prism diopters (Δ) in the primary position. He showed RHT 6Δ in right gaze, RHT 2Δ in left gaze, RHT 12Δ in right head tilt, and orthotropia in left head tilt. The right eye showed limitation of elevation and depression on adduction, and the left eye showed overdepression on adduction. MR images showed an absent right trochlear nerve with a hypoplastic ipsilateral superior oblique muscle.

Conclusions

Congenital Brown syndrome may be associated with an absent trochlear nerve and hypoplastic superior oblique muscle suggesting an etiologic mechanism of congenital cranial dysinnervation disorder.

Superior oblique palsy: a complication of endoscopic sinus surgery

A 34-year-old woman with chronic sinusitis and nasal polyps was treated with bilateral pansinusotomy. Postoperatively, she had a unilateral superior oblique paresis. We suspect that superior oblique damage occurred without involvement of the medial rectus because of inadvertent entry of the endoscopic probe through the superior lamina into the left orbit.

A variant of canine tooth syndrome--presentation and management

We describe a variant of canine tooth syndrome managed with combined inferior rectus recession and Faden operation of the contralateral eye.

Superior oblique muscle palsy after frontal sinus mini-trephine

OBJECTIVE

The aim of this study is to present a case of superior oblique muscle dysfunction after a frontal sinus mini-trephine.

METHODS

This is a case report of an 18-year-old woman where a mini-trephination approach and endoscope were used to open and marsupialize a symptomatic, opacified type IV cell within the left frontal sinus. After surgery, the patient developed a persisting diplopia; a left superior oblique muscle palsy was diagnosed. Nine cadaveric dissections of the trochlea were undertaken to clarify mechanisms for potential trochlear damage.

RESULTS

Cadaveric dissection reveals that the trochlea is more than a simple pulley; it is a complex structure in close proximity to the orbital rim. The superior oblique tendon telescopes and is surrounded by a vascular sheath that could be easily traumatized.

CONCLUSION

Damage to the trochlea could occur, as the periosteum is elevated from bone or during healing. Alternatively, prolonged traction on soft tissue near the trochlea could cause swelling of the vascular sheath, fibrosis, and hypomobility of the superior oblique tendon. Careful siting of the incision for external frontal sinus surgery as well as careful retraction of skin flaps and periosteal elevation are all techniques used, which should reduce the risk of damage to the trochlea.

A case of acquired Brown syndrome after surgical repair of a medial orbital wall fracture

A case of acquired Brown syndrome caused by surgical repair of medial orbital wall fracture is reported in the present paper. A 23-year-old man presented at the hospital with right periorbital trauma. Although the patient did not complain of any diplopia, the imaging study revealed a blow-out fracture of the medial orbital wall. Surgical repair with a calvarial bone autograft was performed at the department of plastic surgery. The patient was referred to the ophthalmologic department due to diplopia that newly developed after surgery. The prism cover test at distant fixation showed hypotropia of the right eye, which was 4 prism diopters (PD) in primary gaze, 20 PD in left gaze, while orthophoric in right gaze. Eye movement of the right eye was markedly limited on elevation in adduction with normal elevation in abduction with intorsion in the right eye present. Forced duction test of the right eye showed restricted elevation in adduction. Computerized tomography scan of the orbits showed the right superior oblique muscle was entrapped between the autografted bone fragment and posterior margin of the fracture. When repairing medial orbital wall fracture that causes Brown syndrome, surgeons should always be careful of entrapment of the superior oblique muscle if the implant is inserted without identifying the superior and posterior margin of the orbital fracture site.

High-resolution magnetic resonance imaging demonstrates varied anatomic abnormalities in Brown syndrome

INTRODUCTION

Although Brown syndrome classically is considered to be limited to the SO tendon sheath and trochlea, it does not always respond to SO surgery. We investigated mechanisms of Brown syndrome by magnetic resonance imaging (MRI).

METHODS

Three patients with congenital and 8 with acquired Brown syndrome were compared with matched normal subjects under a prospective protocol of high-resolution, multipositional orbital MRI using surface coils. Muscle size and contractility were determined using digital image analysis.

RESULTS

Five of 8 patients with acquired Brown syndrome had a history of trauma or surgery and demonstrated extensive scarring, avulsion, or fracture of the trochlea. One of the 8 had a cyst in the SO tendon. One congenital and one acquired case demonstrated inferior displacement of the lateral rectus (LR) pulley in adduction, with a normal SO tendon-trochlear complex. Such cases of Brown syndrome responded to surgical stabilization of the LR pulley. Two congenital cases had clinical findings of ipsilateral SO palsy confirmed on MRI by atrophy or absence of the SO belly. In congenital absence of the SO belly, the anterior tendon was present but terminated directly on the trochlea.

CONCLUSION

High-resolution MRI demonstrates a variety of abnormalities in patients presenting with Brown syndrome, including atrophy or absence of the SO belly. Management in Brown syndrome should be tailored to the pathophysiology of the individual patient.

Ophthalmic complications of endoscopic sinus surgery

The intimate anatomical relationship between the orbit and the paranasal sinuses places the orbit and its contents at risk of harm from primary pathologic processes of the sinuses. In the absence of ophthalmic signs or symptoms, ophthalmologists are not routinely involved in the management of patients with sinus disease. Occasionally, some patients may develop ophthalmic complaints after surgical intervention. The orbit, optic nerve, extraocular muscles, and lacrimal drainage system are susceptible to injury during endoscopic sinus surgery. The risk of injury is related to the skill of the sinus surgeon, history of previous surgery, extent and severity of disease, and anatomic variation. Furthermore, recent advances in endoscopic sinus surgery, in particular the use of powered cutting instruments, has resulted in a novel mechanism of injury to the ocular structures.

Retrieval of lost medial rectus muscles with a combined ophthalmologic and otolaryngologic surgical approach

PURPOSE

To report retrieval of a medial rectus muscle completely detached from the globe and lost in the orbital tissue in four eyes.

METHOD

A lost medial rectus muscle was retrieved in four eyes of four patients with either a transcutaneous medial orbitotomy approach or a transnasal endoscopic ethmoid sinus approach.

RESULTS

The lost medial rectus muscle was successfully retrieved in all four patients. One patient lost the medial rectus muscle secondary to trauma, and the other three cases resulted from complications of strabismus surgery. The mean preoperative angle of exotropia was 44 prism diopters. The endoscopic approach was attempted in three patients, and the medial rectus muscle was successfully found in two of these patients. In one case in which the endoscopic approach was used, an image guidance system was used to aid in finding the lost medial rectus muscle. The endoscopic approach was abandoned in one case in which the medial rectus muscle could not be identified after extensive searching, but the muscle was subsequently found by means of the transcutaneous medial orbitotomy approach. A transcutaneous medial orbitotomy alone was used to find the lost medial rectus muscle in one of the cases. The postoperative ocular deviation for primary position at distance fixation was a mean of 24 prism diopters of exotropia. With one additional operation in two patients, the mean ocular deviation was less than 12 prism diopters.

CONCLUSION

We successfully retrieved a lost medial rectus muscle in four patients with the use of nontraditional strabismus surgical techniques. We effectively combined techniques taken from both ophthalmology and otorhinolaryngology to help solve this difficult problem.

Treatment of subtotal medial rectus myectomy complicating functional endoscopic sinus surgery

During the past 2 decades, the introduction of functional endoscopic sinus surgery (FESS) has dramatically improved the treatment of sinus disorders. However, a variety of orbital complications have been reported, including optic nerve damage, hemorrhage, infection, compromise of the lacrimal drainage apparatus, and strabismus. At least 10 cases have reported damage to the medial rectus muscle. (1-8) Treatment options for such patients have been limited, especially because most are adults at risk for anterior segment ischemia after transposition of vertical rectus muscles. We describe 2 patients whose medial rectus myectomies were repaired by using nonabsorbable "hang-back" sutures in combination with a botulinum toxin (Botox) injection of the antagonist lateral rectus muscle. Good primary position alignment was achieved in both patients, and one patient was able to regain binocular function. We recommend this surgical approach, especially in patients at increased risk for anterior segment ischemia.

Slipped and lost muscles and other tales of the unexpected. Philip Knapp Lecture

Loss of a rectus muscle may occur as a rare complication of strabismus surgery. In addition, extraocular muscles may become traumatically detached from the globe when they rupture or are transected as the result of an injury or during the course of retinal detachment or paranasal sinus or orbital surgery. Although the clinical features of a slipped muscle may resemble those of a lost muscle, the findings at the time of reoperation are distinct. Also the etiology, and therefore the prevention, of a slipped muscle differs from that of a lost muscle. It is likely that slipped muscles and even some lost muscles are underdiagnosed and represent a significant cause of unexpected overcorrection or undercorrection. Unless the displaced muscle is appropriately advanced, it can be extremely difficult to correct the associated strabismus, yet locating and repairing either a lost or slipped muscle can be challenging and is by no means always successful. Current concepts pertaining to the etiology, recognition, and management of slipped and lost muscles will be discussed.

Autogenous fascia augmentation of a partially extirpated muscle with a subperiosteal medial orbitotomy approach

INTRODUCTION

Endoscopic sinus surgery can result in serious extraocular muscle dysfunction. The medial rectus muscle is more frequently affected than other extraocular muscles.

METHODS

A transconjunctival subperiosteal medial orbitotomy was successful in retrieving a partially extirpated medial rectus muscle after endoscopic sinus surgery.

RESULTS

A previous attempt to localize this muscle by conventional surgery with extensive exploration was unsuccessful. A Hummelsheim procedure was also abandoned after a rupture of the nasal aspect of the inferior rectus muscle occurred.

CONCLUSION

The approach we describe allowed adequate visualization of the posterior orbital content, as well as adequate space for suture placement.

Superior oblique luxation and trochlear luxation as new concepts in superior oblique muscle weakening surgery

PURPOSE

We used superior oblique luxation and trochlear luxation as new surgical procedures to treat acquired Brown's syndrome and superior oblique muscle overaction.

METHODS

We studied nine patients (11 eyes) who underwent trochlear surgery between 1988 and 1993. Four patients had acquired Brown's syndrome and five had superior oblique muscle overaction. In five patients (six eyes) the trochlea was incised to luxate the superior oblique tendon out of the trochlea. In four patients (five eyes) the trochlea was luxated out of its fossa via a periosteal approach without opening the trochlea itself.

RESULTS

The mean follow-up was 18 months (range, nine to 33 months). Postoperatively, eight patients showed subjective and objective improvement. One patient with painful traumatic acquired Brown's syndrome had no objective improvement but obtained relief of pain.

CONCLUSIONS

These new techniques are a successful alternative in the treatment of acquired Brown's syndrome and superior oblique muscle overaction.

Hypertropia following trochlear trauma

Hypertropia following trauma to the trochlea is rare. The more widely recognized response of the trochlea to trauma is hypotropia or acquired Brown syndrome. We observed three cases of hypertropia following penetrating trauma to the trochlea. Each had computerized tomography and/or magnetic resonance imaging to assist in the understanding of the mechanism of the observed superior oblique dysfunction. The clinical course of these cases was variable. Awareness of the damaged trochlea's capacity to respond as a hypertropic as well as a hypotropic syndrome will allow for improved management of these unusual patients.

Strabismus following endoscopic intranasal sinus surgery

Two patients developed exotropia with limited medial rectus function following endoscopic intranasal ethmoid sinus surgery. In both patients, fractures occurred in the medial orbital wall. The first patient required horizontal rectus muscle surgery to regain ocular alignment. The second required no surgery, but was left with limited horizontal motility secondary to scarring at the fracture site. While endoscopic techniques improve the surgeon's view of sinus anatomy, they do not eliminate the risk of entering the orbit and causing ocular complications.

Bilateral consecutive superior oblique palsy following fronto-ethmoidal sinusitis

A 61-year-old woman developed a left superior oblique palsy as a result of frontoethmoidal sinusitis. After stabilization, the left inferior oblique and right inferior rectus were recessed. Three years later, she developed a right superior oblique palsy associated with fronto-ethmoiditis. The right inferior oblique and left inferior rectus were recessed.

Ophthalmic complications of sinus surgery

Seven patients with orbital complications of sinus surgery seen over a 10-year period are reported. Severe intraoperative orbital hemorrhage occurred in three patients while undergoing external or intranasal ethmoidectomy. In one patient, an avulsed anterior ethmoidal artery was identified as the source of bleeding, whereas in two others bleeding was due to snaring of orbital tissues. In two of these three cases, intraoperative recognition and prompt treatment of the expanding hematoma resulted in preservation of vision. Motility disturbances due to extraocular muscle injury occurred in two patients after intranasal ethmoidectomy and in one patient after a Caldwell-Luc procedure. Bilateral blindness resulted from transection of both optic nerves in one patient during bilateral intranasal endoscopic ethmoidectomies. Recommendations for prevention, intraoperative recognition, and management of such ophthalmic complications of sinus surgery are given.

Invasive sinonasal polyps causing ophthalmoplegia, exophthalmos, and visual field loss

In a 20-year-old man with a history of sinonasal polyps, bilateral ophthalmoplegia, exophthalmos, and optic nerve dysfunction developed. Radiologic imaging showed a polypoid mass filling the nose and sinuses, eroding into the pituitary fossa, basal cisterns, and orbits, and compressing the cavernous sinuses. Six months after bilateral maxillary, ethmoid, and sphenoid exploration, ocular motility returned to normal, but there remained mild generalized visual field loss in the right eye. The pathologic specimen showed polypoid respiratory mucosa with acute and chronic inflammation as well as eosinophiles.

Brown's syndrome

Brown's syndrome is a well-recognized clinical disorder of ocular motility manifesting most notably a restriction of active and passive elevation in adduction. The original name, "superior oblique tendon sheath syndrome," is no longer appropriate, since it has been shown that the tissue surrounding the anterior superior oblique tendon is blameless as a restrictive force. "True" and "simulated" as descriptive modifiers should also be discarded, as they relate to the disproven sheath concept. Brown's syndrome occurs as a congenital or acquired, constant or intermittent condition; the common link is restriction of free movement through the trochlea pulley mechanism. The various etiologic theories are reviewed and the spectrum of medical and surgical treatments are described and evaluated. Evidence suggests that subtypes of Brown's syndrome lie on a single continuum and that spontaneous resolution occurs in each group, probably more often than previously recognized. A simplified classification scheme is encouraged and possible future directions in Brown's syndrome research are introduced.

Ophthalmic considerations in fronto-ethmoidal mucocoeles

The pre- and post-operative ophthalmic consequences of fronto-ethmoidal mucocoeles are considered in a prospective series of 22 patients. Proptosis, lateral and inferior displacement, diplopia and restriction of ocular mobility were the commonest presenting problems. Following external fronto-ethmoidectomy, proptosis and displacement resolved completely in the majority of patients. One third of patients experienced a transient exacerbation of diplopia but this resolved in most patients. Persistent diplopia occurred in seven patients and required medical correction in four and surgery in one. This was due in all cases to underaction of the superior oblique muscle and probably to backward displacement of the trochlea which may be avoided by careful surgical re-attachment.

Simulated superior oblique tendon sheath syndrome

Three patients with simulated Brown's superior oblique tendon sheath syndrome are presented. With the use of computed tomographic (CT) findings, the site of the pathology could be demonstrated. In all three patients, there were definite abnormal findings in the anterior sheath of the reflected tendon of the superior oblique. The abnormal findings in one case were confirmed at the time of surgery. Therapy in two of the cases was determined by the abnormal findings on the CT scan.

Acquired Brown's syndrome from blunt orbital trauma

Blunt trauma to the supero-medial orbit resulted in an isolated Brown's syndrome in two patients. One recovered spontaneously in three weeks; the other had a good outcome after surgery two years post trauma. Recognition of the characteristic motility abnormality and forced duction testing will differentiate this condition from other, more common, motility disorders caused by orbital trauma. Spontaneous resolution may occur but in persistent deviations a superior oblique muscle weakening procedure should be considered.