The authors report the case of a 27-year-old male with ventriculoperitoneal shunt (VPS) for hydrocephalus presenting with episodic transient binocular visual loss (TBVL) and headache. Complete physical, bedside shunt examination and funduscopy were unremarkable. Laboratory investigation, shunt series and imaging studies failed to reveal any acute abnormalities. Interrogation of the shunt system identified a valve malfunction which was corrected with resultant symptomatic relief and the patient was discharged home in stable condition. VPS malfunction occurs secondary to infection or mechanical failure such as obstruction, tubing fracture, shunt migration and over drainage. Resultant raised intracranial pressure leads to symptoms of headache, nausea, vomiting and gait abnormalities. Visual defects including blindness has been occasionally reported from shunt malfunction. Rare complications include cerebrospinal fluid oedema, colonic perforation, paraparesis and parkinsonism. TBVL due to shunt malfunction remains an uncommon presentation and requires a high index of clinical suspicion while evaluating these patients.
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Transient visual loss, also known as amaurosis fugax may be mono or binocular although the latter tends to occur more rarely.1 Bilateral symptoms suggest involvement of the optic chiasm, tract, radiation or the visual cortex. The causes may range from minor to serious disorders and include migraine, visual seizure, vertebrobasilar ischemia.2 3 Raised intracranial pressure (ICP) in patients with hydrocephalus has been associated with visual disturbances including transient and permanent blindness.4,–,6 There have been occasional reports of visual loss in patients with ventriculoperitoneal shunt (VPS) malfunction, often associated with papilloedema with or without optic atrophy.7,–,10 We present here a case of transient binocular visual loss (TBVL) as a rather early manifestation of shunt malfunction with good clinical recovery following correction of the malfunctioning valve which underscores the need to consider this diagnosis in the differential under relevant circumstances while investigating for TBVL.
A 27-year-old male with hydrocephalus status post VPS placed at 14 years of age presented with TBVL lasting a few hours. He developed a sudden onset ‘white out’ of his vision in both eyes lasting a few hours with several more transient episodes occurring subsequently and associated with a throbbing retro orbital headache. Over the preceding 2 to 3 months, he had symptoms of nausea, memory disturbances and occasional unsteady gait. The patient was afebrile and his physical examination was unremarkable, more pertinently, there were no focal neurological deficits. Eye examination including funduscopy did not reveal any acute abnormalities or disc oedema except for a visual acuity of 20/50 in both eyes without correction. Shunt palpation at bedside was unremarkable.
Laboratory tests including complete blood count, sedimentation rate, the metabolic panel, fasting lipids, C reactive protein, methylmalonic acid were within normal limits. Shunt series were unremarkable and without any evidence of disruption or kinking. CT angiography (CTA) of head revealed a dilated ventricular system having a mild mass effect on the internal cerebral vein due to some interval increase in amount of hydrocephalus and no venous sinus thrombosis was noted. Comparison with a CT of the head done 8 months prior showed no significant change in ventricle size (figures 1 and 2). MRI and magnetic resonance angiography of the head did not reveal any other acute abnormalities.
In our patient with a history of VPS and presenting symptoms suggestive of raised ICP, shunt malfunction was considered first and investigation aimed at identifying this was initiated with bedside evaluations and imaging studies mentioned earlier. The other differentials included TBVL due to vascular causes including vertebrobasilar ischaemia, vasculitis and migraine. Although infection can be one cause of shunt malfunction, in our patient, who was afebrile throughout his course of illness, had no elevation of white cell count or the acute phase reactants, it was considered much lower on the differential. Hence cerebrospinal fluid (CSF) analysis was not done. With the patient having persistent symptoms and investigation remaining inconclusive, it was decided to further explore the shunt system in the operating room.
Definitive treatment included interrogation of the shunt system wherein a valve malfunction was identified. The CSF pressure proximal to the dysfunctional valve was noted to be greater than 35 cm of H2O. The malfunctioning valve was replaced with consequent good flow of CSF. The patient also received symptomatic treatment with analgesics, supportive care during his hospitalisation.
Outcome and follow-up
Following surgical correction, the patient improved symptomatically and he was discharged home in stable condition. The patient has had no recurrence of his symptoms for a little over a year now since his initial presentation.
VPS malfunction can occur secondary to infection or mechanical failure.11 12 Infection rates reported in various studies have varied from 11 to 19.7%.11 13 14 Infection is seen more often in newborns and usually in the 1st 6 months after shunt placement.11 14 15 The infecting organisms reported are usually part of the skin flora commonly Staphylococcus epidermidis but occasionally also due to Staphylococcus aureus, Streptococcus species and gram negative bacilli.13 14 16 Mechanical failures may occur due to obstruction at the ventricular catheter, fracture of the tubing, migration of the shunt in part or whole and due to over drainage.17 Shunt malfunction can result in obstruction to CSF flow with resultant raised ICP which may lead to symptoms of headache, nausea, vomiting as was noted in our patient. Patients with untreated hydrocephalus or those with VPS malfunction have been reported to present with visual field defects and transient or permanent blindness.6 10 The blindness may be due to involvement of either the anterior or posterior visual pathways. More commonly blindness associated with both untreated hydrocephalus and shunt malfunction has been reported following papilloedema with consequent ischaemia of optic nerve and from optic atrophy.9 10 Infrequently, involvement of the posterior visual pathways or the cortex due to impaired circulation and/or occipital lobe infarcts have led to visual loss in this patient population.18 The interesting aspects in our patient include the absence of overt clinical findings of raised ICP such as papilloedema or optic atrophy as well as paucity of findings on imaging studies and bedside shunt palpation. Visual disturbances with little or no papilloedema have been reported in experimental studies conducted on animals.19 Parahippocampal gyrus herniation with distortion of the lateral geniculate bodies and optic tracts were the main findings in these animals. It was hypothesised that short lasting blindness noted in some animals was due to transient parahippocampal herniation.19 This theory or possible effect of increased ICP on the posterior circulation may be the likely pathogenesis of the transient visual loss in our patient. Some of the rare complications of VPSs reported in literature include CSF oedema, formation of abdominal CSF pseudocyst, colonic perforation, paraparesis and parkinsonism.20,–,25
Conversely, sudden decrease of CSF pressure after correction of hydrocephalus or malfunctioning shunt has also been attributed to transient visual loss.8 TBVL has been reported with basilar migraine, occipital seizures and vertebro basilar ischemia.26 27 Vasoconstriction involving the basilar artery, especially close to its bifurcation into the posterior cerebral arteries can affect occipital cortex bilaterally resulting in binocular visual disturbance or loss. This has been proposed as a rare form of migraine affecting the basilar artery that can cause TBVL.26 27 Occipital seizures as noted on an electroencephalogram (EEG) can present with bilateral visual loss, often transient, and may be associated with either the actual seizure episode or occur during the post ictal phase.2 The duration of the visual loss varied. Others have noted an association between basilar migraine and occipital seizures both occurring in the same patient with bilateral visual loss.27 Similarly, TBVL can occur as a transient ischaemic attack involving the basilar artery either due to atherosclerosis, arterial stenosis or embolic phenomenon of the posterior circulation which would affect bilateral occipital cortices.3 Rare causes of TBVL reported in literature include antiphospholipid antibody syndrome, following coronary artery bypass graft in the postoperative phase, cerebral venous sinus thrombosis and valsalva manoeuvre.28,–,31
Investigation for TBVL includes sedimentation rate, tests for hypercoagulability, cardiac and vasculitis investigation, carotid duplex ultrasound, MRI, EEG and in patients with VPSs a complete assessment both bedside and imaging to exclude shunt malfunction. Investigation in our patient was not indicative of infection or ischemic events. But with continued symptoms, it was felt necessary to further assess for shunt malfunction. Interrogation revealed a shunt valve malfunction. Following correction, his symptoms improved remarkably which led us to believe TBVL in our patient was a manifestation of VPS malfunction. However, visual loss has not been described as a complication in several long-term studies on ventriculoperitoneal or ventriculoatrial shunts.11 32 33 Thus TBVL remains a relatively uncommon form of presentation of VPS malfunction. Possibly in our patient this was a rather early presentation which resulted in good recovery of function following surgical revision of the shunt.
▶ It is necessary to have a high index of suspicion for shunt malfunctions in patients with VPS presenting with TBVL.
▶ TBVL in any patient should also prompt investigation to exclude ischemic events or infection.
▶ Early diagnosis and revision surgery for shunt malfunction may help prevent permanent blindness in patients with no significant papilloedema, optic atrophy or infarcts.
▶ With frequent reports of visual defects in patients with shunt malfunction, it would be prudent to have a regular ophthalmologic evaluation in patients with VPS to prevent permanent deficits.
Abdelazim Sirelkhatim, MD, Clinical Assistant Professor, Director of Neurology Education and Neurology Clerkship Director, University of Tennessee College of Medicine Chattanooga. Daniel Kueter, MD, Neurosurgeon, Chattanooga Neurosurgery and Spine, Erlanger Hospital. Patrick J Bowers, Jr, MD, Ophthalmologist, Erlanger Hospital. Avni S Kapadia, MD. Poonam Kafle, MD, Department of Radiology, Erlanger Hospital.
Competing interests None.
Patient consent Obtained.