Near Reflex Paresis - A Rare Presentation of Arachnoid Cyst

Abstract

Case ReportA 10 years old boy came with the complaints of double vision for while reading for the past 3 weeks. There was no associated headache or vomiting. His performance in the school was normal. On examination, he was found to have BCVA of 6/6 in both eyes. Cover test revealed orthophoria for the distance. Cover test for near could not be done as he could not converge the eyes. Extraocular movements were full. Pupils were 3 mm in size and reacting to direct and indirect light reflex in both eyes, but there was no constriction of pupils for attempted near reflex. Convergence was poor with near point of convergence >45 cm. Near point of accommodation was found to be 50 cm. Humphrey field test tried but he had many fixation losses.Cycloplegic refraction was normal. Fundus examination was normal. No evidence of papilloedema was present. Neurological examination was normal. He was diagnosed as a case of near reflex paresis. MRI brain scan with contrast was done and it revealed a large well defined extra-axial CSF intensity lesion involving the right middle cranial fossa with fronto-temporal mass effect on the optic chiasma-the features suggesting of Arachnoid cyst (type iii) (Figure 1 & 2). Abstract DiscussionArachnoid cysts are a congenital disorder, and most cases begin during infancy; however, onset may be delayed until adolescence.2 Arachnoid cysts are seen in up to 0.2 to 1.7% of the population.3 Arachnoid cysts can be relatively asymptomatic or present with insidious symptoms. Symptoms vary by the size and location of the cyst(s), though small cysts was usually have no symptoms and are discovered only incidentally. On the other hand, a number of symptoms may result from large cysts. The onset of the symptoms and signs are usually due to cortical irritation, compression of the cerebral parenchyma, or the obstruction of CSF circulation.They reduce the perfusion and metabolism in surrounding cortical regions. 4 Its symptoms are very diverse, such as headaches, epilepsy, hydrocephaly, intracranial hypertension, macrocephaly, calvarium prominence, cranial nerves palsies, vertigo, discrete proptosis, hemiparesis, mental retardation or even be asymptomatic. It is more common in males and on the left side.5 MRI is the diagnostic procedure of choice because of its ability to demonstrate investigation the exact location, extent, and relationship of the arachnoid cyst to adjacent brain or spinal cord. The near reflex or accommodation reflex is characterised by pupillary constriction to sharpen the