PubMed Health⌕ Search

Biomedical subjects

Alki Liasis

Publications and source records attributed to Alki Liasis.

8 recordsLinked to original sources
PubMed2006

Monitoring visual function in children with syndromic craniosynostosis: a comparison of 3 methods.

OBJECTIVE: To compare visual acuity, optic disc appearance, and transient pattern reversal visual evoked potentials as markers of possible visual dysfunction in children with syndromic craniosynostosis. METHODS: Serial visual acuity, optic disc appearance, and pattern reversal visual evoked potential data were recorded in 8 patients with syndromic craniosynostosis before and after cranial vault expansion. The pattern reversal visual evoked potentials were analyzed using linear regression modeling, applied to the N80 to P100 amplitude. RESULTS: Serial optic disc appearances were available for all 8 patients and visual acuities for 7 patients. The visual acuity deteriorated in only 1 patient, improved in 4, and fluctuated in 2, before surgery. Of the 8 patients, 3 showed no papilledema in either eye at any time, 3 showed progressive bilateral swelling before surgery, and 2 exhibited only unilateral disc swelling. In all 8 patients, there was a trend for the N80 to P100 amplitude to decrease before surgery and to increase, in all but 2 patients, after surgery. CONCLUSIONS: This study suggests that neither optic disc appearance nor visual acuity assessment alone is a reliable marker of potential visual dysfunction in children with syndromic craniosynostosis. It also suggests that the pattern reversal visual evoked potential can provide early evidence of visual dysfunction before vault expansion surgery in these children; this dysfunction may recover postoperatively.

Child↗
PubMed2006

Prevalence of abnormal pattern reversal visual evoked potentials in craniosynostosis.

BACKGROUND: The purpose of this study was to examine the prevalence and type of changes observed in the pattern reversal visual evoked potentials recorded at the first assessment of children with craniosynostosis. METHODS: Visual evoked potentials were recorded from 114 patients with craniosynostosis. Eighty-one patients were syndromic and 33 were nonsyndromic. No patient had received any craniofacial surgical intervention. At the time of the test, 22 of 40 patients were aged 6 months and younger, and 18 patients were between 6 months and 1 year of age. Pattern reversal visual evoked potentials were recorded from a midoccipital electrode positioned 3 cm above the inion. The pattern reversal visual evoked potentials elicited to 50' checks with three reversals per second viewed with both eyes were analyzed for n80-p100 amplitude, p100 latency, and breadth of waveform. RESULTS: Sixty percent of patients had abnormal pattern reversal visual evoked potentials to 50' checks. This did not show a significant association with age, or classification of craniosynostosis. CONCLUSIONS: The high prevalence of abnormal pattern reversal visual evoked potentials to a robust stimulus suggests that visual pathway dysfunction, as measured electrophysiologically, can affect a majority of patients with craniosynostosis. This study indicates that a baseline evaluation of all children with craniosynostosis at their first presentation is essential if subsequent electrophysiologic visual pathway monitoring is to take place.

Craniosynostoses↗
PubMed2005

The value of visual evoked potentials in the evaluation of periorbital hemangiomas.

PURPOSE: To present a case of a child with an extensive facial hemangioma in whom the suspicion of intracranial involvement was raised by visual evoked potential (VEP) evaluation. DESIGN: Observational case report. METHODS: VEP analysis was performed using flash and pattern stimuli to determine whether treatment intervention other than occlusion therapy was needed. RESULTS: VEP analysis indicated a marked transoccipital asymmetry in the flash and pattern VEP suggestive of right hemispheric dysfunction. Neuroimaging showed intracranial extension of the hemangioma. CONCLUSION: The VEP evaluation is a noninvasive technique performed in the awake child. This case highlights the usefulness of VEP analysis in the management of extensive periocular capillary hemangiomas and its use as a modality to identify potential intracranial involvement. Large plaquelike facial capillary hemangiomas may have possible underlying dural involvement suggestive of PHACES syndrome.

Amblyopia↗
PubMed2004

Fourth and sixth cranial nerve injury after halo traction in children: a report of two cases.

BACKGROUND: Spinal traction is the application of a longitudinal force to the spinal column as a means of stabilizing a damaged or abnormal spine. Although not well documented in the ophthalmic literature, complications include cranial nerve palsies, with the sixth nerve being most commonly affected. Fourth nerve palsies have not previously been reported to our knowledge. We present 2 cases of combined fourth and sixth palsies after cervical traction. METHODS: Retrospectively, we reviewed the ophthalmic findings in 2 children with diplopia after spinal traction. RESULTS: Case 1 suffered a traumatic rotatory atlantoaxial subluxation and underwent halo traction. Case 2 required traction to correct a scoliosis secondary to osteogenesis imperfecta. In both cases, sixth nerve palsies were apparent soon after traction. Careful orthoptic examination revealed additional fourth nerve involvement. After 3 months, both cases showed partial resolution of the cranial nerve injuries. CONCLUSIONS: Cranial nerve injury may occur with spinal traction. Fourth nerve palsy may be underreported because of masking by a coinciding sixth nerve palsy.

Abducens Nerve Injury↗
PubMed2004

Event-related potentials in pediatric cochlear implant patients.

OBJECTIVE: The main objective of this study was to assess the correlation of auditory event related potential (ERP) measures with behavioral assessment data to identify if ERPs including mismatch negativity (MMN) can be used to categorize cochlear implant patients into good and poor performers. DESIGN: We investigated auditory event-related potentials to standard and deviant speech stimuli presented in a pseudorandom sequence in 35 cochlear implant patients between the ages of 7 and 17 yr. We compared the occurrence, latencies, and amplitudes of P1, N2, and MMN with overall behavioral outcome in these children. Behavioral measures included category of auditory performance scores and speech intelligibility rating scores. RESULTS: Auditory ERPs in response to standard stimuli were identifiable in 30 of 35 patients, demonstrating a major positive component (P1) followed by a negativity (N2) with absence of N1 in all patients. The P1 component in prelingually deaf patients showed a statistically significant reduction in its latency with increasing duration of implant use. MMN was recorded in 80-85% of star performers but in only 15-20% of poor performers. Patients with higher SIR scores demonstrated statistically significant longer duration of MMN compared with those with a lower SIR score. CONCLUSIONS: These results indicate that MMN can be used to assess the functional status of the auditory cortex in terms of auditory memory and discrimination in young children with cochlear implants and may provide an objective mechanism for differentiating good from poor performers.

Adolescent↗
PubMed2003

Speech and non-speech processing in hemispherectomised children: an event-related potential study.

Although hemispherectomy is now used as a radical treatment for intractable seizures in a number of centres, there have been limited electrophysiological studies investigating post-procedure auditory-speech processing and recovery or reorganisation. We therefore recorded auditory event-related potentials (ERPs) evoked by pure tones and syllables employing a 51-channel electrode array concentrated over the functional hemisphere in 17 patients (nine males, mean age 14.2 years) who had undergone hemispherectomy for intractable seizures; eight of the patients had congenital brain damage and nine had sustained their initial insult at an age of 1 year or older. For comparison, recordings were made from 10 controls (five males, mean age 13.5 years). Responses from patients consisted of five small amplitude components restricted to the functional hemisphere whose scalp polarity was opposite to the ERPs observed in control subjects. The topography of the auditory ERPs in the patients was localised to the centro-temporal regions of the functional hemisphere in comparison to the midline distribution observed in control subjects. As in the control subjects, the latencies of the components evoked by tones were shorter than those evoked by syllables in both left and right hemispherectomised children. In addition, further analysis of the N1 and P2 component revealed increased syllable latencies in left hemispherectomised children only. The results of this study suggest that the left hemisphere alone may be more efficient at processing both pure tones and syllables compared to the right or both together.

Acoustic Stimulation↗
PubMed2003

Sustained raised intracranial pressure implicated only by pattern reversal visual evoked potentials after cranial vault expansion surgery.

Craniosynostosis, the premature fusion of cranial sutures, may be associated with raised intracranial pressure (ICP) with or without a reduced intracranial volume. Regardless of the aetiology, raised ICP may result in optic neuropathy, the timely detection of which can prevent further visual deterioration. Raised ICP is usually treated with craniofacial surgery such as cranial vault expansion. In this case study, we recorded serial pattern reversal visual evoked potentials (pVEPs) and obtained digital optic disc images before and after cranial vault expansion surgery. The amplitude of the pVEPs continued to decrease after cranial vault expansion surgery, prompting further neuroimaging that implicated a blocked ventriculo-peritoneal shunt. Only after shunt revision did the pVEP amplitude increase. Throughout the monitoring period, there was no change in the appearance of either the right or left optic disk, nor a consistent change in visual acuity.

Child↗