Transient blindness following intracranial pressure changes in a hydrocephalic child with a V-P shunt

Strabismus in hydrocephalus patients

PURPOSE

To evaluate the characteristics and outcomes of strabismus in patients with hydrocephalus.

METHODS

A retrospective chart review of patients with strabismus and hydrocephalus is performed in the Department of Pediatric Ophthalmology between 2012 and 2018.

RESULTS

Seventeen patients between the ages of 6 months and 13 years met the criteria of strabismus and hydrocephalus. Although all had developmental delay, five patients out of 17 were premature (lower than 36 weeks of gestation). All patients had ventriculoperitoneal shunt placement for congenital hydrocephalus. Three patients had exotropia, whereas 14 had esotropia. Glasses were prescribed to 13 patients: hyperopic correction in 12 and myopic correction in one patient. Surgical correction with bimedial recession was performed in five patients. Four of them achieved successful ocular alignment.

CONCLUSIONS

Children with hydrocephalus most likely have esotropia. Although good ocular alignment is achieved with surgical correction in some patients, some patients may benefit from glasses.

[Semiology of ventriculoperitoneal shunting dysfunction in children - a review]

INTRODUCTION

Ventriculoperitoneal shunting (VPS) is a treatment of the hydrocephalus that may dysfunction. The clinical presentation of shunt dysfunction is variable. We therefore decided to focus on the clinical presentation of VPS malfunction in children, as this condition requires immediate emergency treatment and because of the sometimes confusing signs of intracranial hypertension in a shunted child.

MATERIALS AND METHODS

We searched PubMed with the following groups of keywords: (dysfunction OR blockage) AND shunting AND hydrocephalus; shunt complications AND hydrocephalus; hydrocephalus AND shunt AND malfunction. Articles dealing with ventriculo-atrial shunt were excluded. A total of 79 articles were retained for analysis (English and French). Case reports were excluded.

RESULTS

The clinical presentation varies by age: vomiting and alterated level of consciousness are the most frequent signs in older children, whereas infants present more often with raised intracranial pressure symptoms such as nausea, vomiting, irritability and bulging fontanel. Drowsiness is a good predictor of VPS dysfunction. An asymptomatic presentation is rare but possible. Abdominal presentation is also possible, ranging from abdominal discomfort to peritonitis. Fever, occurring a short time after the last intervention, and irritability are good predictors of shunt infection. Pumping the chamber of the VPS has a weak positive predictive value (12%). Shunt dysfunction can lead to death, with an estimated mortality rate at 1% per year during the first years.

CONCLUSION

It is essential to be aware of the variability of the clinical presentation of VPS dysfunction, because of the potential severity of this condition. Also it is important to pay attention to the comments of the parents, especially if the child experienced a previous shunt malfunction.

Visual disturbance following shunt malfunction in a patient with congenital hydrocephalus

A 25-year-old woman presented with complaints of nausea and headache. She had been treated with a ventriculoperitoneal shunt for hydrocephalus when she was 7 months old. Her bilateral optic discs showed moderate atrophy. Right visual acuity allowed only perception of hand movement and left visual acuity was 0.02 (1.2). Computed tomography (CT) showed mild ventricular dilation but no periventricular lucency. Intracranial pressure (ICP) was not high when the shunt valve was punctured. Her visual acuity deteriorated 5 days after the consultation. She was referred again 8 days after the first consultation. The bilateral optic discs were completely pale. Both pupils were dilated on admission, and the bilateral direct light reflexes were absent. The patient could slightly detect only green light stimulus. CT showed moderate enlargement of the ventricle. ICP was 47 cmH(2)O when the shunt valve was punctured. Shuntgraphy showed obstruction of the shunt at the distal end of peritoneal catheter. Emergent total shunt revision was performed. She could detect dark stimulus and the still-dilated left pupil had recovered direct light reflex on the next day. The visual acuity was 0.01 (0.7) on the left 6 months after the operation, although she was blind in the right eye and the bilateral optic discs were completely pale. Visual loss associated with shunt failure remains a major morbidity in shunted congenital hydrocephalus. Early diagnosis and shunt revision may allow visual recovery.

Flash visual evoked potentials are unreliable as markers of ICP due to high variability in normal subjects

BACKGROUND

Previous publications have suggested a high correlation between flash visual evoked potential (F-VEP) N2 peak latency and intracranial pressure. This would enable F-VEP to be used as a non-invasive and inexpensive method to estimate ICP in a number of settings. However, basic knowledge about variability across subjects and test-retest properties of the F-VEP is lacking.

METHODS

Fifteen healthy adult subjects were tested on three different occasions. F-VEP responses were recorded using international standards.

FINDINGS

For the tested population, mean N2 latency was 65.7 ms (SD 10.7 ms) and the range was 48-110 ms. Intra-individual variability was high, in four of the 15 subjects more than 15 ms between testing sessions. The same was found for P2 latency and for N2 and P2 amplitudes. The response waveform was very variable and unambiguous marking of peaks was often difficult. One out of the 15 subjects had a very poorly developed F-VEP response, but a normal pattern-reversal VEP response.

CONCLUSIONS

F-VEP has a wide range of latency, amplitude and waveform across normal subjects. A large proportion of subjects also had a high intra-individual variability over time. This variability makes F-VEPs unreliable as a marker for intracranial pressure, and caution in interpreting F-VEP changes in clinical work is advised.

Transient binocular visual loss: a rare presentation of ventriculoperitoneal shunt malfunction

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.

Visual field constriction in children with shunt-treated hydrocephalus

OBJECT

Many ophthalmological abnormalities are described in conjunction with hydrocephalus. The results of visual field diagnosis remain a matter of further discussion. The aim of this study was to investigate visual field deficits in children with shunt-treated hydrocephalus.

METHODS

All children over 6 years of age treated for hydrocephalus at the authors' institute between December 2007 and December 2008 were included in the study. The children underwent an ophthalmological investigation for strabismus and binocular function, ophthalmoscopy, visual acuity, and refraction. The special focus was the visual field diagnosis, which the authors established in all children with cognitive conditions. The investigation was made by using the Goldmann visual field examination (kinetic perimetry). Children with and without visual field defects were compared concerning age at the time of ophthalmological examination, genesis of hydrocephalus, and fronto-occipital horn ratio measured on current CT or MR images.

RESULTS

Complete investigations were undertaken in 56 children (24 girls and 32 boys, mean age 15.1 years). The following orthoptic pathological entities were diagnosed: 29 children have a strabismus in 29 cases, 17 of these have an exotropia, 12 an esotropia, 4 children a hypotropia, 2 a hypertropia and 3 children a heterophoria. A nystagmus was found in 10 children. The ocular fundus investigation showed 13 children with an optic nerve atrophy. A visual field diagnosis was possible in 44 of the 56 patients and was incomplete in 12 patients with cognitive deficits or inadequate compliance. In 24 of 42 children there was a concentric visual field constriction between 10° and 50° out of the center. Children with visual field deficits were older than those with a normal visual field (p = 0.051). Nine of 10 children with postmenigitic hydrocephalus had a visual field defect (p = 0.025). In children with visual field defects the fronto-occipital horn ratio was significantly higher (p = 0.013).

CONCLUSIONS

The results suggest that children with shunt-treated hydrocephalus have a higher risk of having ophthalmological abnormalities. Visual field deficits are often a problem in these patients. A diagnostic visual field examination can complete the ophthalmological monitoring in patients with hydrocephalus, especially in patients with large ventricles. Children with postmeningitic hydrocephalus should be ophthalmologically monitored more frequently and intensively.

Tuberculous meningitis-related optic neuritis: recovery of vision with thalidomide in 4 consecutive cases

Blindness is an uncommon but devastating complication of tuberculosis meningitis. The main causes are chronically raised intracranial pressure (hydrocephalus and/or tuberculomas) or direct involvement of the optic chiasm or optic nerves by the basal arachnoiditis (inflammation and/or compression). Antituberculosis therapy combined with corticosteroids and control of intracranial pressure constitutes the mainstay of therapy for tuberculous meningitis. Despite these treatment measures, some patients develop blindness, mainly as a result of progressive optochiasmatic arachnoiditis. This led us to explore the role of adjuvant thalidomide therapy, and we describe the dramatic recovery of vision in 4 consecutive cases. Clinical recovery was accompanied by marked radiological improvement on magnetic resonance imaging (MRI) of the brain.

Continuous remission of newly diagnosed and relapsed central nervous system atypical teratoid/rhabdoid tumor

Atypical teratoid/rhabdoid tumors (AT/RT) are highly malignant lesions of childhood that carry a very poor prognosis. AT/RT can occur in the central nervous system (CNS AT/RT) and disease in this location carries an even worse prognosis with a median survival of 7 months. In spite of multiple treatment regimens consisting of maximal surgical resection (including second look surgery), radiation therapy (focal and craniospinal), and multi-agent intravenous, oral and intrathecal chemotherapy, with or without high-dose therapy and stem cell rescue, only seven long-term survivors of CNS AT/RT have been reported, all in patients with newly diagnosed disease. For this reason, many centers now direct such patients, particularly those under 5 years of age, or those with recurrent disease, towards comfort care rather than attempt curative therapy. We now report on four children, two with newly diagnosed CNS AT/RT and two with progressive disease after multi-agent chemotherapy who are long term survivors (median follow-up of 37 months) using a combination of surgery, radiation therapy, and intensive chemotherapy. The chemotherapy component was modified from the Intergroup Rhabdomyosarcoma Study Group (IRS III) parameningeal protocol as three of the seven reported survivors in the literature were treated using this type of therapy. Our four patients, when added to the three reported survivors in the literature using this approach, suggest that patients provided this aggressive therapy can significantly alter the course of their disease. More importantly, we report on the first two survivors after relapse with multi-agent intravenous and intrathecal chemotherapy treated with this modified regimen.

Changes in visual acuity associated with shunt failure

OBJECT

The object of this article was to report on a retrospective analysis of the clinical findings in a series of patients with changes in visual acuity associated with shunt failure.

METHODS AND RESULTS

Over a 10-year period, 350 patients underwent revisions for shunt failure. The clinical course of patients who demonstrated changes in visual acuity (VA) before or during hospitalization were reviewed; follow-up was achieved using outpatient records and telephone calls with physicians, family, or caregivers. Six patients (4 male) ranging in age from 2.5 years to 40 years demonstrated changes in vision associated with shunt failure. The youngest patient lapsed into coma before transfer and showed bilateral occipital lobe infarctions on the CT scan. Three patients had no complaints referable to the visual system prior to revision. Two patients with symptoms lasting more than 21 days showed unequivocal signs of increased intracranial pressure. Serial CT scans remained unchanged in 2 patients. A 3rd patient showed questionable progression in ventricular volume, while another patient's ventricles dilated after a period of 48-72 h. Four patients demonstrated a pattern of aqueductal stenosis, long-term shunting without revision, small ventricles, and poor outpatient follow-up. Four patients showed partial or complete recovery following revision.

CONCLUSIONS

Changes in vision are uncommon and can be an isolated finding associated with shunt failure. Patients with aqueductal stenosis, long-term shunting without revision, and small, potentially non-compliant ventricles may be at risk of this complication. Misdiagnosis or inadequate follow-up places these patients at additional risk, but rapid revision can result in partial or complete recovery.

The light-flash-evoked response as a possible indicator of increased intracranial pressure in hydrocephalus

Surgical treatment of infantile hydrocephalus by shunt implantation may result in suboptimal intracranial pressure. Major neurological impairments and death are usually prevented by shunt treatment, but minor sequelae may persist or develop. The introduction of adjustable shunts has improved the possibilities of optimizing shunt function and minimizing the risk of such impairments. However, it is still impossible to determine the intracranial pressure without invasive measurements. Clinical findings and procedures such as computed tomography (CT) are not always enough to allow a conclusion as to whether a child's signs and symptoms are the result of suboptimal intracranial pressure (shunt dysfunction) or are of another etiology. With the aim of reducing the number of invasive pressure measurements and CT scans, we investigated the effect of increased intracranial pressure on the visual evoked response (VER). Binocular light flash stimuli of supramaximal intensity were used and VER recordings were performed from Oz and Cz. The VER results from a group of 31 infants and children with hydrocephalus and 2 children with pseudotumor cerebri were compared with responses from a control group of 35 healthy children. The results show that a subpotential, P' (P-prime), usually just preceding P1 (P100), had an increased latency ( > 96 ms) in all hydrocephalic children before surgery. The P' latency in this group was usually even above 110 ms. The latencies of other VER potentials were also increased but not as consistently as P'. After surgical intervention the VER latencies decreased and usually normalized. The P' latency in four children in the control group was just above the borderline latency, but was less than 110 ms.(ABSTRACT TRUNCATED AT 250 WORDS)

Shunt failure without ventriculomegaly proclaimed by ophthalmic findings

Four patients who developed increased intracranial pressure from ventricular shunt failure suffered a delay in diagnosis because magnetic resonance imaging of the brain did not show ventriculomegaly and because ophthalmic findings were initially overlooked or misinterpreted. None of the patients had the conventional manifestations of shunt failure: severe headache, nausea, vomiting, and depressed consciousness. Three patients suffered marked, permanent vision loss from chronic papilledema. These cases affirm that increased intracranial pressure may occur in shunt dependency without producing either conventional clinical symptoms or signs on imaging of the brain. Because ophthalmic manifestations may be the major clues to diagnosis, and because irreversible loss of vision is possible if these clues are overlooked, consideration should be given to periodic ophthalmological examination of shunt-dependent patients.

Automated evoked potential monitoring

We have developed a computer system for use in the operating room and intensive care unit for the automated acquisition and classification of flash evoked potentials. The project goals were to: (1) acquire evoked potentials without user intervention; (2) recognize, label, and trend important parameters; and (3) alarm if parameters deviate too far from normal. The system consists of a Nicolet Pathfinder, programmed for periodic flash visual evoked potential acquisition and a personal computer for analysis. Analysis software utilizes the C+ +language. The system has been tested on sixteen cases, determinations of specific waveforms were validated ex post facto by two experts. Three parameters in each of three channels were correctly recognized in more than 87% of all waveforms acquired. No signals at all were obtained in only 0.8% of all samples.

Reversible opisthotonus following intracranial pressure changes in Chiari malformation

A shunted myelodysplastic child with Chiari II malformation presented with shunt malfunction and opisthotonus. Correction of a distal obstruction lead to an initial improvement followed by overdrainage of cerebrospinal fluid and repetition of an opisthotonic posture. The possible mechanisms which unmask lower brainstem dysfunction in Chiari malformation when intracranial hyper- or hypotension exist, are discussed.

The effect of intracranial hypotension on cerebral blood flow in a feline model

Intracranial hypotension is a known clinical entity but its pathophysiology has been meagerly studied. Any setting with cerebrospinal fluid leakage or drainage can cause intracranial hypotension. A feline model of kaolin induced chronic hydrocephalus with controlled cerebrospinal fluid drainage from a lateral ventricle yields reproducible intracranial hypotension of up to -15 torr for several hours to -80 torr of about 10 minutes. The magnitude of this hypotension is significantly greater than can be attained by cisterna magna drainage. This new model allows multiple cerebral parameters to be studied during intracranial hypotension. In 11 cats with stable blood pressure and intracranial hypotension of at least -15 torr, regional blood flow utilizing the hydrogen clearance method in the cerebral cortex and subcortical nuclei was unchanged relative to the baseline. These results imply that: 1) cerebral vascular autoregulation is maintained during significantly increased perfusion pressure due to negative intracranial pressure, 2) the symptomatology of clinical intracranial hypotension is not due to decreased cerebral perfusion.

Reversible visual loss after shunt malfunction

Report on three hydrocephalic, shunt dependent children, who became blind due to shunt malfunction and rapidly decreased intracranial pressure. They regained vision several days (one case) or several months (2 cases) after shunt revision. The related literature is reviewed and possible pathophysiological mechanisms are discussed.