Delayed progressive visual loss following wrapping of bilateral clinoidal aneurysms: recovery of vision and improvement in neuroimaging during corticosteroid treatment

Reinforcement with muscle, cotton, fibrin glue, or some other material is an alternative to clipping in some intracranial aneurysms¹; the surgeon must balance the need to create local inflammation (to reinforce the arterial wall) with the risk that the inflammation will spread and damage adjacent structures. Wrapping of clinoidal aneurysms, in particular, rarely may produce delayed and severe visual loss or ocular motor dysfunction.^2–7 The clinical course and potential outcome of damage to the visual pathway, ocular motor tracts, or both remains controversial, as does the optimum management when visual loss occurs. We present the case of a patient who developed severe bilateral visual loss and neuroimaging evidence of inflammation in the paraclinoid and suprasellar regions 2 months after wrapping of bilateral clinoidal aneurysms with cotton and fibrin glue, but who recovered visual function and whose neuroimaging appearance improved after treatment with systemic corticosteroids.

Case report

A 61 year old woman underwent magnetic resonance imaging (MRI) and angiography after experiencing a minor stroke. The studies revealed aneurysms of the clinoidal portion of both internal carotid arteries. Endovascular treatment was unsuccessful. Accordingly, craniotomy was performed. As neither aneurysm could be clipped, both were wrapped with cotton gauze saturated with fibrin glue. The patient did well postoperatively until 2 months after surgery, when she noted blurred vision in the right eye. An incomplete left homonymous hemianopia associated with a mild right optic neuropathy was found, and MRI showed a thickened, nodular, enhancing area in the paraclinoid and suprasellar regions with involvement of both optic nerves and the optic chiasm. Observation was elected, but the patient developed a severe headache with worsening visual loss over the next 6 weeks. Repeat MRI showed an increase in the extent of the area of the enhancing process (fig 1A), and the patient was admitted to hospital.

Figure 1.

 T1 weighted coronal MRI of head with gadolinium contrast (A) obtained at the time of admission to hospital. An enhancing lesion surrounds the right internal carotid artery (ICA) and is adjacent to a smaller enhancing lesion abutting the left ICA. The process extends into the right temporal lobe. (B) 2 months after initiation of steroid therapy. Marked reduction in both the size and extent of the lesions as well as the degree of contrast enhancement is noted.

At admission, visual acuity was 1/400 temporally in the right eye and 20/40 in the left eye. Colour vision was markedly diminished in both eyes. Kinetic perimetry showed an incomplete, incongruous left homonymous hemianopia (fig 2A). There was no relative afferent pupillary defect. Extraocular motility was normal, as were corneal and facial sensation. The right optic disc was minimally pale; the left optic disc appeared normal. Lumbar puncture showed normal cerebrospinal fluid glucose and protein levels; there were 14 mononuclear white blood cells. Complete blood count and serum chemistries were normal. An acute infectious aetiology was determined to be unlikely, and the patient was treated with intravenous dexamethasone 10 mg every 4 hours. Within 48 hours, visual acuity had improved to 20/200 in the right eye and 20/30 in the left eye, and the visual field of the right eye had expanded temporally. Intravenous dexamethasone was continued at 6 mg every 4 hours for 2 days, and then reduced to 4 mg every 4 hours. After 7 days of treatment, the patient’s visual acuity had improved to 20/40 in the right eye and to 20/20 in the left eye, with further expansion of the peripheral visual field of the right eye. Repeat MRI revealed marked reduction in the size and enhancement of the basal process. The patient was discharged home on a 2 week tapering oral dose of dexamethasone.

Figure 2.

 Kinetic perimetry with incongruous left homonymous hemianopia (A) at the time of admission and (B) performed after 4 weeks of steroid therapy, with marked expansion of the peripheral visual field of each eye. Static perimetry results (Humphrey 24-2, SITA Standard), both eyes, demonstrate the scotomatous nature of the residual visual field defects (C) after 4 weeks of steroid therapy and (D) 2 years after steroid treatment for vision loss.

Four weeks after discharge, the patient had visual acuity of 20/20 with slightly diminished colour vision in each eye. An incongruous, left homonymous hemianopia remained (fig 2B–C), but as this visual field deficit was scotomatous rather than absolute, the patient had been able to return to driving and was now able to perform all of the activities of daily living. MRI 6 weeks after discharge showed no evidence of enhancement or mass effect in the paraclinoid or suprasellar region (fig 1B). Two years after discharge and without further treatment, the patient remains well with stable vision and visual fields (fig 2D).

Comment

Reinforcement of unclippable intracranial aneurysms with autologous or alloplastic materials was proposed over 80 years ago, with subsequent studies showing that only a subset of these materials produce the desired local effect.¹ Unfortunately, some patients in whom this treatment is used develop visual loss, occasionally several months or years after the surgery.^6–9 Although both ischaemia and infection are thought to be inciting factors in some cases,¹⁰ most cases appear to result from an inflammatory reaction to the material used to wrap the aneurysm.^6,7 The reason that the material incites such a reaction is unknown.

High quality MRI permits recognition of the inflammatory process that usually is found in cases of vision loss.^3,4 Unlike in recent reports,^2–4,6 our patient presented with a markedly enhancing bilateral process that, after corticosteroid treatment, diminished greatly in both size and degree of contrast enhancement, providing an anatomical correlate with the functional improvement demonstrated clinically. In our patient, therapy was initiated approximately 2 months after the visual loss ensued, as was treatment in the other cases where no diminution of the inflammatory mass was seen. Thus, as noted by others,⁶ it seems clear that some patients recover spontaneously, some improve with steroid treatment, some improve with surgery, and some do not improve regardless of treatment.

To date, there has been no reported demonstration by MRI of size reduction of the inflammatory mass after medical therapy alone. We demonstrate here that cotton associated inflammation may respond dramatically to anti-inflammatory therapy both clinically and by neuroimaging. Furthermore, this case suggests that wrapping of intracranial aneurysms with cotton or cotton products reinforced with fibrin glue is justified when no suitable alternative exists, and that treatment with corticosteroids should be pursued aggressively should visual loss and imaging evidence of postoperative inflammation result, as non-surgical treatment may result in both anatomical and functional improvement. Should this treatment be unsuccessful, a neurosurgeon should be prepared to explore the patient and attempt debridement of the inflammatory process.