Abulia and Post-Tap Agitation in Normal-Pressure Hydrocephalus

The “frontal–subcortical” dementia pattern of NPH affects processing speed, attention, working memory, and executive function, but spares “cortical” capacities such as praxis, speech, sense modalities, recognition, and long-term memory.⁷ Noncognitive symptoms are common: 73% of patients in a Japanese study reported significant apathy, and 10% to 25% of patients also reported positive symptoms of delusions, irritability, disinhibition, agitation, anxiety, and stereotyped behaviors.⁸ NPH patients may also exhibit depression, mania, psychosis, catatonia, obsessive-compulsive behavior, and personality change.^8–11 In most case reports, shunting resulted in reduction or remission of the neuropsychiatric symptoms.

Our patient was diagnosed with probable NPH and displayed neuropsychiatric symptoms of abulia, verbal stereotypy, and executive dysfunction. Abulia, a more severe version of apathy, is characterized by lack of spontaneity, deficiency in initiation, inertia, reduction in excursion of motion, poor attention, and easy distractibility.¹² Other possible etiologies of the patient’s abnormal mental status, such as seizure, delirium, depression, serotonin toxicity, alcohol withdrawal, and mania were essentially ruled out by the described work-up. Both the old right basal ganglia lacunar infarct, as well as selective serotonin reuptake inhibitor (SSRI) and methylphenidate withdrawal, may have predisposed the patient to development of an abulic state, given reports in the medical literature of apathy ameliorated by methylphenidate.¹³ It is tempting to speculate that the patient may have displayed signs of NPH much earlier if not for the stimulant in his medication regimen.

After one dose of intravenous midazolam and a large-volume LP, the patient’s apathetic state lysed and quickly evolved into an excited, agitated state that did not respond to intravenous haloperidol. It is unlikely that midazolam caused conversion to prolonged agitation, given the ultra-short half-life of the drug and the subsequent effectiveness of lorazepam. Lumbar punctures may cause headache and carry a small risk of exacerbating tonsillar herniation, but are not normally associated with severe mental status changes in the medical literature. The MRI obtained the day after LP did not show evidence of over-drainage or slit-ventricle syndrome. The only literature describing a similar post-tap agitation is C. Miller Fisher’s 1983 address on abulic and agitated states, where he described five of his own cases of normal-pressure hydrocephalus in which ventriculovenous shunt was followed by a prolonged violent, confused state.¹⁴ Fisher’s general theory of agitation postulated a “release” of frontal lobe activity in what he called the “mesencephalic frontal activating system.” By contrast, abulia and akinetic mutism reflected a reduction in this system’s activity. This is supported by the research evidence of increased frontal cerebral perfusion after shunting.^4,5

Catatonia is a syndrome of abnormal behaviors and movements due to neuromedical insults that can present in either retarded or excited forms, sharing several clinical features in common with NPH and apathy.¹⁵ Severe gait immobility, slowed processing, and incontinence in NPH may be indistinguishable from the stupor, posturing, and negativism of catatonia. Several cases of obstructive hydrocephalus associated with catatonia have been reported, but only one case involving normal-pressure communicating hydrocephalus was reported by Foltz and Ward in 1955.¹¹ The patient in our case may have manifested a syndrome of catatonic stupor with NPH, which transformed into excited catatonia that responded to intravenous lorazepam, which is the first-line treatment for catatonia.

Catatonia in NPH may be underreported for several reasons: the biomechanical etiology of NPH suggests a mechanical treatment, the removal of CSF, rather than medicinal or electroconvulsive therapies as for catatonia; and practitioners in neurological or neurosurgical settings may not be familiar with the syndrome of catatonia. Abulic and catatonic states in NPH should be considered early, as a benzodiazepine challenge can be a safe, rapid, and effective intervention. Dopaminergic agents are occasionally successful in reversing both akinetic mute and catatonic withdrawal cases, which may both be considered mesencephalic frontal activating-system deficit states.