A 43-year-old man with a history of HIV infection who is noncompliant with highly active antiretroviral therapy comes to the office due to progressive memory loss and cognitive decline over the last several years. The patient has problems with attention, concentration, and speech. In the past few months, he has become more apathetic and increasingly lethargic. More recently, he has had difficulty with balance and has fallen on multiple occasions. The patient has had no headache, tremor, change in vision, fever, nausea/vomiting, or urinary incontinence. His brother has a history of severe intellectual disability and epilepsy. Mini-Mental State Examination score is 18/30, and the patient appears emotionally blunted. He also has postural instability and difficulty performing fine motor tasks. Noncontrast head CT scan reveals diffuse cortical atrophy with some enlargement of the ventricles, as shown in the exhibits.
This patient's condition can be best described as which of the following?

Question

A 43-year-old man with a history of HIV infection who is noncompliant with highly active antiretroviral therapy comes to the office due to progressive memory loss and cognitive decline over the last several years.  The patient has problems with attention, concentration, and speech.  In the past few months, he has become more apathetic and increasingly lethargic.  More recently, he has had difficulty with balance and has fallen on multiple occasions.  The patient has had no headache, tremor, change in vision, fever, nausea/vomiting, or urinary incontinence.  His brother has a history of severe intellectual disability and epilepsy.  Mini-Mental State Examination score is 18/30, and the patient appears emotionally blunted.  He also has postural instability and difficulty performing fine motor tasks.  Noncontrast head CT scan reveals diffuse cortical atrophy with some enlargement of the ventricles, as shown in the exhibits. 
 This patient's condition can be best described as which of the following?

Quizplus · Accepted Answer

Cerebrospinal fluid (CSF) circulates in the ventricular system and subarachnoid space and is constantly secreted by the choroid plexus and absorbed by granulations of the arachnoid mater. Hydrocephalus is defined as enlargement of the ventricles (with or without elevated pressure) caused by either central neuronal volume loss (eg, hydrocephalus ex-vacuo) or excessive CSF accumulation. Patients with neurodegenerative diseases (eg, AIDS dementia) can develop hydrocephalus ex-vacuo due to significant cortical atrophy, which allows the ventricles to expand while maintaining normal CSF pressure. Ventricular enlargement caused by excessive CSF accumulation typically occurs due to obstructed CSF circulation (noncommunicating hydrocephalus) or absorption (communicating hydrocephalus). In communicating hydrocephalus, CSF flows freely between the ventricles and subarachnoid space, but there is decreased CSF reabsorption at the arachnoid granulations (Choice A). There are 2 major types of communicating hydrocephalus: Normal-pressure hydrocephalus (NPH) is caused by a chronic reduction in CSF absorption at the arachnoid villi, resulting in enlargement of the ventricles out of proportion to the overlying cortical atrophy. Because the impaired CSF absorption is chronic, the ventricles enlarge slowly, allowing the CSF pressure to normalize. Patients with NPH typically present with early ataxia followed by frontal lobe dementia and urinary incontinence. High-pressure hydrocephalus results from more acute impairment in CSF absorption (eg, cerebral venous sinus thrombosis, meningitis, acute subarachnoid hemorrhage) and typically presents with a change in mental status, seizure, headache, and focal neurologic deficits. (Choice C) Lissencephaly (agyria) is a congenital absence of gyri. This condition is typically accompanied by severe mental retardation and seizures. On gross examination and imaging, the brain surface has a smooth appearance. (Choice D) Obstruction of CSF flow within or between the ventricles and subarachnoid space is termed noncommunicating hydrocephalus. Congenital abnormalities (eg, aqueductal stenosis, Arnold-Chiari malformation) and tumors can lead to this type of hydrocephalus, resulting in symptoms of elevated intracranial pressure. In noncommunicating hydrocephalus, only the ventricles that are proximal to the obstruction are dilated. (Choice E) Pseudotumor cerebri (idiopathic intracranial hypertension) refers to elevated intracranial pressure in the absence of ventricular enlargement on imaging. This disorder classically presents in young, obese women with headache, papilledema, and possible visual loss due to optic neuropathy. (Choice F) Transtentorial (uncal) herniation can occur due to an intracranial mass (eg, tumor, hemorrhage) or cerebral edema. This may lead to compression of the ipsilateral oculomotor nerve and posterior cerebral artery. A fixed, dilated pupil on the same side as the lesion is often the first sign of uncal herniation. Educational objective: Hydrocephalus is an enlargement of the ventricles (with or without elevated pressure) caused by either neuronal volume loss (eg, hydrocephalus ex-vacuo) or excessive cerebrospinal fluid accumulation (due to flow obstruction or impaired absorption). Neurodegenerative diseases (eg, AIDS dementia) can be associated with hydrocephalus ex-vacuo due to significant cortical atrophy, which allows the ventricles to expand while maintaining normal pressure.

A 43-Year-Old Man with a History of HIV Infection Who