Normal-pressure hydrocephalus, also known as Hakim-Adams syndrome, is a clinical condition described in 1965[^1] and characterized by enlargement of the Ventricular system without markedly elevated intracranial pressure. Patients with normal-pressure hydrocephalus usually present with the following characteristic features:
Clinical presentation of the Hakim triad
Normal Intracranial pressure during a Lumbar puncture
The symptoms can be alleviated by shunt placement or cerebrospinal fluid drainage.
Initially, the cause of normal-pressure hydrocephalus was described as idiopathic. However, in some patients with normal-pressure hydrocephalus, it is the consequence of a primary disease and is then referred to as secondary normal-pressure hydrocephalus. The following conditions may cause secondary normal-pressure hydrocephalus:
Post-subarachnoid hemorrhage
Post-traumatic
Post-meningitis
Following surgery in the posterior cranial fossa.
Following radiotherapy of the brain
Increased head circumference[^3]
Neoplastic meningiosis
Deficiency of the Pacchionian granulations
This article will focus primarily on primary idiopathic normal-pressure hydrocephalus rather than secondary normal-pressure hydrocephalus.
Incidence
The incidence of idiopathic normal-pressure hydrocephalus is 5.5/100,000 per year[^2].
Symptoms
Hakim's triad is the typical symptom triad in patients with normal-pressure hydrocephalus and consists of gait instability, urinary incontinence, and memory impairment. However, this symptom complex is not pathognomonic for normal-pressure hydrocephalus and may also be observed in patients with vascular dementia, Alzheimer's disease, or Parkinson's disease. Patients are typically over 60 years of age, and men are affected slightly more often than women. The literature also contains occasional case reports of psychiatric disorders associated with normal-pressure hydrocephalus: depression[^5], bipolar disorder[^6], aggressiveness[^7], and paranoia[^8]. Headaches generally do not occur as a symptom of normal-pressure hydrocephalus[^4].
Gait instability
Usually, gait instability is the main component of the symptoms and occurs in almost all patients with idiopathic normal-pressure hydrocephalus. The gait is broad-based with short steps. Patients often feel as though their feet are "stuck" to the floor, resulting in the so-called "magnetic gait," and have difficulty turning and initiating steps[^4].
Memory impairment
In normal-pressure hydrocephalus, memory impairment and Bradyphrenia are particularly prominent.
Urinary incontinence
Patients with normal-pressure hydrocephalus typically present with urge incontinence and impaired inhibition of bladder emptying.
Diagnostic workup
The evaluation of normal-pressure hydrocephalus is multimodal.
Imaging
Enlargement of the ventricular system can be assessed on CT or MRI.
