Gait impairment associated with urinary incontinence and cognitive decline is suggestive of normal-pressure hydrocephalus. Gait and stance difficulties are usually an early sign, and they may appear before, shortly after, or simultaneously with intellectual changes. Urinary incontinence is typically a late symptom. Gait disturbance may be a unique presentation of normal-pressure hydrocephalus, and incontinence is the most commonly missing symptom from the triad. Urinary urgency may sometimes precede the development of incontinence. Fecal incontinence is rare and appears in more advanced stages. The clinical manifestations of normal-pressure hydrocephalus are insidious and, if untreated, this condition is inevitably progressive with gradual progression of dementia and advancement to an akinetic state.
Patients with normal-pressure hydrocephalus walk slowly, are unsteady, and have a wide base. Steps are short with reduced step height, a pattern of gait referred to as "magnetic gait" (Fisher 1982). Postural instability is also common, with increased risk of falls. Turning is awkward and en block with multiple steps. Patients often complain about leg weakness, tiredness, and occasional numbness or burning sensations. These symptoms fluctuate from day to day. In advanced stages, standing, and later sitting, may become impossible. Neurologic examination may reveal a mild degree of spasticity with increased muscle stretch reflexes in the lower extremities, and Babinski signs also may be present. Upper extremities are initially spared, but changes in handwriting, poor coordination on fine motor tasks, and postural tremor have been reported in later stages.
The gait difficulties in normal-pressure hydrocephalus must be distinguished from those caused by weakness. Lower extremity strength in normal-pressure hydrocephalus is preserved. Motor abilities can be tested with patients sitting or lying down by asking them to imitate walking, riding a bicycle, or other motions. Typically, they can perform these tasks without obvious deficit, and these abilities are preserved until relatively late stages. This pattern of gait disturbance indicates gait "apraxia" rather than muscle weakness.
Normal-pressure hydrocephalus may have additional manifestations beyond a classic triad. Motor impairment may also affect the upper limbs, and slowing of rapid alternating movements is seen commonly in patients with normal-pressure hydrocephalus; a successful shunting of hydrocephalus also improves the dexterity in the upper extremities (Nowak et al 2006).
Cognitive decline varies widely in its severity. Dementia is characterized by prominent attention deficit, memory impairment, and executive (frontal lobe) dysfunction. Most patients are apathetic; bradyphrenia and depression must be considered. Aphasia, other than anomia, and apraxia are usually not prominent. However, cognitive symptoms in normal-pressure hydrocephalus are not limited to features of so-called subcortical dementia (eg, abulia, bradyphrenia, distractibility, memory deficit). Focal cortical deficits (aphasia, apraxia, agnosia) may occur as well, blurring the distinction between dementia in normal-pressure hydrocephalus and the primary degenerative dementias. Behavioral symptomatology can be marked in some patients. Akinetic mutism and alteration of consciousness are found in the later stages.