Normal pressure hydrocephalus is a type of hydrocephalus caused by the build-up of cerebrospinal fluid, characterized clinically by dementia, abnormal gait and urinary incontinence. Normal pressure hydrocephalus may occur due to secondary causes or may be idiopathic.
This disease stems from endocrine processes. Normal Pressure Hydrocephalus is described with an incidence-rate of about 6 / 100.000.
Though some symptoms of normal pressure hydrocephalus mimic Alzheimer’s disease and Parkinson’s disease, the combination of dementia, urinary incontinence and abnormal gait in conjunction is not common in either disease. Thus, the diagnosis of NPH must be specific.
Prognosis of normal pressure hydrocephalus is variable. Permanent neurological deficit/death is reported in 6% of all cases, with surgery requiring in 22% of the cases. There is a good long-term survival rate of 39% [7].
Complications
Shunt surgery can cause complications such as catheter breakage, cerebral infarct, infection, seizures, catheter breakage and in some cases even death in up to 10 % of the patients [8].
About 50% of the patients with NPH have idiopathic cause. Other secondary causes are head injury, meningitis, tumors, previously compensated congenital hydrocephalus and subarachnoid hemorrhage [2].
Normal pressure hydrocephalus affects the elderly with prevalence ranging from 3.3 per 100,000 (age: 50 to 59 years), 49.3 per 100,000 (age: 60 to 69 years) and 181.7 per 100,000 (age: 70 to 79 years). In a study in Japan, NPH is seen in 2.9% of the elderly subjects, while data from a Norwegian study showed the incidence of 5.5 in every 100,000 [3] [4] [8].
The clinical symptoms of NPH result from the distortion of the central portion of the corona radiata. This alteration is believed to occur due to the distended ventricles.
Nuclear imaging studies indicate the interstitial edema of the white matter in the brain and compression of the brainstem structures leading to impaired bloodflow, which manifests as dysfunction of gait and urinary incontinence. There is also a distortion of the periventricular limbic system, causing dementia in such patients [5].
Hydrocephalus is a condition when there is accumulation of surplus cerebrospinal fluid (CSF) in the ventricles of the brain, and the drainage and absorption of extra CSF is compromised. In order to compensate this excess fluid, the ventricles enlarge causing several symptoms of normal pressure hydrocephalus (NPH).
This phenomenon is mostly seen in older patients, with the average age of patients being above 60 years. NPH develops slowly, and affects the parts of brain that control the bladder, the legs, and the cognitive functions such as memory, problem solving, speaking and reasoning. This decline of the cognitive process can cause dementia. Other symptoms of NPH are urinary incontinence, and abnormal gait. Since the symptoms of NPH mimic those of Alzheimer’s disease and Parkinson’s disease, the diagnosis of this disease remains a challenge [1].
Definition
Normal pressure hydrocephalus (NPH) is generally seen in patients with ages 60 and above. This disease develops slowly and affects the brain, bladder and legs. Loss of cognitive functions such as memory, problem solving, speaking and reasoning are affected by NPH.
Cause
Though half of the patient with NPH have idiopathic cause, the secondary causes are head injury, meningitis, subarachnoid hemorrhage and tumors.
Symptoms
The common symptoms of the NPH are dementia, abnormal gait and urinary incontinence.
Diagnosis
Family history and personal history detail the symptoms of the disease, allowing for the diagnosis of NPH. Physical examination of the patient forms the first step to manage the disorder. Though there is no specific lab test available to diagnose NPH, some imaging tests can be useful in correct diagnosis.
Treatment
Surgery is the most effective treatment modality to manage NPH.