[Indications and surgical technique of the endonasal decompression of the optic nerve from an HNO medical viewpoint]

The therapeutic efficacy of endoscopic optic nerve decompression and its effects on the prognoses of 96 cases of traumatic optic neuropathy

BACKGROUND

Traumatic optic neuropathy (TON) is an important cause of severe loss of vision due to blunt or penetrating head trauma. The pathogenesis of TON remains unclear, and there are several potential causes for the observed loss in vision. Endoscopic optic nerve decompression (EOND) has been reported to improve the visual prognosis in TON cases, but its efficacy remains controversial. It is important to investigate the therapeutic efficacy of EOND in the treatment of TON and to evaluate the relevant prognostic factors.

METHODS

A retrospective study was conducted to analyze the clinical characteristics and prognoses of 96 TON cases. The χ(2) test and multiple logistic regression analyses were used to evaluate potential prognostic factors.

RESULTS

: The overall rate of EOND effectiveness was 40.6% (39 of 96). A significantly higher effective rate (83.3%) was observed for patients with light perception compared with those without light perception (26.4%, p < 0.05). Univariate and multiple logistic regression analyses identified three variables (no light perception, undergoing EOND 3 days after trauma, and hemorrhage within the ethmoid and/or sphenoid sinus) that were significantly associated with unrecovered visual acuity. Age, loss of consciousness, optic canal fracture, preoperative steroid megadose treatment, and optic nerve sheath incision were all factors that showed no significant correlation with therapeutic efficacy. However, patients with fractures in a single medial wall of the optic canal appeared to have better prognoses than patients with multiple fractures or those with a single fracture in a lateral wall.

CONCLUSIONS

The overall therapeutic efficacy of EOND for the treatment of TON is far from satisfactory, especially for patients without light perception. The factors that impact TON prognoses are complex and may be interrelated. The indication for EOND must be individualized.

LEVEL OF EVIDENCE

III, epidemiological study.

[Traumatic optic nerve neuropathy. Longterm results following microsurgical optic nerve decompression]

BACKGROUND

Traumatic optic nerve neuropathy (TON) is defined as injury to the optic nerve with subsequent vision loss due to head or craniocerebral trauma. The treatment of this disease is the subject of controversial discussions. The purpose of the present study was to investigate pre- and immediate postoperative visual acuity in patients with unilateral TON and to compare the results with the time interval between trauma and surgical intervention.

PATIENTS AND METHODS

A total of 20 patients with unilateral TON and considerable vision loss were examined. All were treated with high dose corticoids and underwent microsurgical optic nerve decompression. Visual acuity was determined pre- and postoperatively. In long-term follow-up visual acuity was determined 3 months postoperatively.

RESULTS

Postoperatively, nine patients (45%) achieved an improvement in visual acuity of more than 0.4, and another three patients (15%) an improvement of ≥0.2. At 3 months postoperatively another four patients achieved a further improvement of their visual acuity of >0.2. A decrease in visual acuity was not observed in any case, nor were major surgical complications.

CONCLUSIONS

Factors which predict good prognosis for vision recovery include a short time interval between trauma and intervention, edema, and/or hematoma of the optic nerve sheath. Factors which predict a worse prognosis are a fracture line directly through the nerve canal, a time period between trauma and intervention of more than 24 h, and initial complete amaurosis.

Evaluation of traumatic optic neuropathy in patients with optic canal fracture using diffusion tensor magnetic resonance imaging: a preliminary report

OBJECTIVE

To investigate the role of diffusion tensor magnetic resonance imaging (DT-MRI) in the evaluation of traumatic optic neuropathy (TON).

METHODS

Six patients with TON underwent DT-MRI prior to decompression surgery. DTV 2 and Volume One 1.44 software were used to measure the fractional anisotropy (FA) and the mean apparent diffusion coefficient (ADC) of the optic nerves. White matter fiber bundle tracking was used to display optic nerves.

RESULTS

Visual acuity was improved in 1 of the 6 patients after surgery. The mean FA of the injured eye declined significantly with regard to that of the normal eye (0.2438 ± 0.0670 vs. 0.4524 ± 0.0531; t = 8. 711; p = 0. 000). The mean ADC on the injured side increased significantly compared with that on the normal side [(1.4172 ± 0.1208) × 10(-3) mm(2)/s vs. (1.0866 ± 0.1179) × 10(-3) mm(2)/s; t = -5.316; p = 0. 003). The continuity of the intracanalicular segment of the optic nerve was interrupted in 3 patients without improved postoperative visual acuity. In 1 patient with improved postoperative visual acuity, the fiber bundle of the optic nerve was somewhat less dense in the injured eye than in the normal eye.

CONCLUSIONS

DT-MRI provides valuable information for evaluating the fibers of optic nerves in TON.

[Therapy of posterior orbital tumors]

Tumors of the posterior orbit require different therapeutic modalities, depending on the histological entity. In the orbit all structures are in close relationship and the endocranium is in the direct proximity. This requires profound knowledge of topographic anatomy and high therapeutic precision. The surgical approach to the posterior orbit via a ventral intraorbital approach is strongly restricted due to the ocular bulb which consumes most space in the anterior orbit. Therefore if the bulb and vision are to be retained extraorbital surgical corridors are predominantly preferred. These are classified into extracranial and intracranial approaches. In detail, the former are medial transethmoidal orbitotomy, caudal transmaxillar orbitotomy and lateral orbitotomy. Frontolateral and frontotemporal orbitotomy as well as frontal, bifrontal and subfrontal orbitotomy are intracranial approaches. Apart from surgical methods there are several forms of radiotherapy which can be applied to orbital tumors under certain indications. Radiotherapy may be performed with external fractionated photon radiation or as stereotactic radiation, with heavy ions or protons or as brachytherapy. In this article various therapeutic interventions to the posterior orbit and the indications and potential side-effects are described.

[Posttraumatic amaurosis after complex frontobasal fracture. Differential diagnosis and therapy]

BACKGROUND

Whether surgical nerve decompression is indicated for the treatment of posttraumatic reduced vision with optic nerve compression in the bony canal has been a subject of controversy for decades. On balance, the recent literature suggests that this procedure is indeed indicated, as a supplement to high-dosed cortisone therapy. The risk of surgery-related side effects is usually rated low in the literature.

CASE REPORT

We report on a woman patient in whom craniocerebral trauma involved a fracture of the left optic canal with unilateral loss of vision. In the decompression operation, intraoperative symptoms gave rise to the suspicion of an arteriovenous fistula, which had not been revealed by computer tomography and which was seen as sufficient grounds for discontinuing the procedure. In addition to a carotid artery-sinus cavernosus fistula (CCF Barrow type A), subsequent angiography revealed a dissected aneurysm at the branching of the occluded ophthalmic artery.

DISCUSSION AND CONCLUSIONS

In decisions on whether surgical relief of pressure on the optic canal is indicated after trauma-related visual loss, the possibility of secondary lesions near the tip of the orbita and the optic canal must be taken into account. These are not always revealed by computer tomography. The indications should be critically weighed up in each individual case, with additional imaging examinations, such as MR-angiography, CT-angiography, or conventional angiography, performed as needed. The options and indications for imaging are discussed. The procedure can by no means be rated as "minimally invasive", as is postulated by some authors.