Giant left parietal lobe arachnoid cyst presenting as early-onset dementia

Abstract

DesCripTionA 56-year-old woman with no significant medical history was brought for evaluation of difficulty with speaking for 1 month. Family reported patient having short-term and long-term memory impairment and gradual cognitive decline over a course of 2 years. Her mother had Alzheimer's dementia in her 60s and the patient attributed her symptoms to Alzheimer's and did not seek medical attention until she developed word finding difficulty. On neurological examination, she had expressive aphasia and scored 20 on Mini-mental state examination (MMSE). Laboratory work-up showed normal haemogram, metabolic panel, thyroid function tests, vitamin B12 and folic acid levels and a negative rapid plasma reagin (RPR) test. MRI showed a giant left cerebral hemisphere arachnoid cyst with 11 mm midline shift to the right (figure 1). She underwent stereotactic craniotomy with microsurgical excision of the arachnoid cyst. Postoperative hospital course was complicated by generalised tonic-clonic seizure, controlled with antiepileptic medications. On 6-week follow-up, patient had resolution of expressive aphasia and mild improvement in her cognitive function.Arachnoid cysts are cerebrospinal fluid-filled sacs located between brain or spinal cord and arachnoid membrane.1 Primary arachnoid cysts are more common and congenital in origin whereas secondary arachnoid cyst can develop as a complication of brain surgery, head injury, tumour or meningitis. 1These comprises about 1% of all intracranial mass with approximately 50%-60% occurring in the middle cranial fossa.1 2 Males are four times more likely to have arachnoid cysts than females.2 Elderly patients with arachnoid cyst usually present with headache, nausea and vomiting, vertigo, gait disturbance and dementia, mimicking chronic subdural haematoma and normal pressure hydrocephalus.

An arachnoid cyst mimicking a symptomatic Alzheimer’s disease

“…Gemäß einer Fallserie mit 299 Erwachsenen treten Arachnoidalzysten mehrheitlich (66 %) temporal und nur selten (12 %) wie in unserem Fall parietal auf [ 7 ]. In der Literatur fanden wir zwei Fallberichte, welche kognitive Defizite bei einer symptomatischen Arachnoidalzyste links parietal beschrieben [ 8 , 9 ]. Bei beiden Patientinnen lagen ähnliche Symptome wie bei unserer Patientin vor; darunter langsam fortschreitende Namens- und Wortfindungsstörungen.…”