A 40-year-old woman comes to the office due to worsening gait disturbances over the past several months. The patient has had difficulty taking steps, as if her feet were stuck to the floor, and she feels unsteady while walking. She has had no falls, headache, vertigo, vision loss, or focal weakness or numbness. Three years ago, the patient had subarachnoid hemorrhage (SAH) from ruptured posterior communicating artery aneurysm, which was treated with endovascular coiling; she has had no recurrent bleeding. She has no other medical conditions and takes no medications. Vital signs are within normal limits. Physical examination shows flat affect and psychomotor retardation. The pupils are equal and reactive to light. The cranial nerves and funduscopic examination are unremarkable. Muscle strength, deep tendon reflexes, and sensation are normal throughout. The gait is slow and wide-based with small steps. MRI of the head is shown in the exhibit. Lumbar puncture reveals normal opening pressure, and the cerebrospinal fluid cell counts and laboratory studies are within normal limits. Which of the following is the most likely cause of this patient's gait disturbance?
Normal pressure hydrocephalus | |
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Normal pressure hydrocephalus is characterized by the accumulation of cerebrospinal fluid (CSF) leading to ventriculomegaly with normal opening pressure on lumbar puncture. Most cases are idiopathic and occur in the elderly; however, secondary disease can occur in those with prior neurologic insults (eg, subarachnoid hemorrhage [SAH], trauma, meningitis) that result in scarring and destruction of the arachnoid granulations responsible for CSF resorption.
Symptoms are classically described as a triad of incontinence, cognitive impairment (eg, psychomotor retardation, apathy), and gait abnormalities; however, all symptoms may not be present in early disease. A magnetic gait with slow, wide-based steps that appear as though the patient's feet are stuck to the ground is characteristic and typically appears early in the disease process. Upper motor neuron signs (eg, spasticity, hyperreflexia) may also occur. The diagnosis is confirmed with improvement of symptoms with large-volume lumbar puncture; ventriculoperitoneal shunt placement is the definitive therapy.
(Choice A) Aqueductal stenosis can also occur after SAH and causes ventricular enlargement; however, symptoms of elevated intracranial pressure (eg, headache, nausea/vomiting) predominate.
(Choice B) Cerebellar degeneration (eg, alcoholic cerebellar degeneration) can cause a wide-based, shuffling gait, but it is also commonly associated with dysarthria and postural instability. Neuroimaging may show cerebellar atrophy, but ventriculomegaly is unexpected.
(Choice D) Vasospasm is a common complication of SAH and results in cerebral ischemia and stroke, but this characteristically occurs within 8 days of the primary bleed. Symptoms develop acutely, correspond to the location of the stroke, and would not progress over a period of months.
(Choice E) Secondary parkinsonism can rarely result from cerebrovascular disease that interferes with the striatonigral pathway. Although gait disturbances are common, they are classically described as shuffling or festinating (quick, short steps). Rigidity, bradykinesia, and pill-rolling tremors are also expected, but ventricular enlargement is not common.
Educational objective:
Normal pressure hydrocephalus (NPH) is characterized by ventriculomegaly with normal opening pressure on lumbar puncture. It classically presents with a triad of incontinence, cognitive impairment, and gait abnormalities; however, all symptoms may not be present in early disease. NPH can be idiopathic or occur secondary to neurologic insults (eg, subarachnoid hemorrhage, trauma, meningitis) that result in scarring of the arachnoid granulations responsible for cerebrospinal fluid resorption.