Infection,the caudate,and movement disorder

To the Editor

A disoriented 24-year-old female student presented with fluctuating fever and acute mutism. Examining doctors did not find any focal neurological deficit. There was no significant medical, psychiatric, travel, drug, or alcohol history.

Working on the diagnosis of meningoencephalitis, the neurologists treated her with intravenous acyclovir and ceftriaxone. During the initial days of treatment, she showed signs of gradual recovery, with increased verbal output. Two weeks later, she was reported to be suddenly ‘unable to maintain a single position for longer than 10 seconds’, often tumbling about in bed. There was intermittent, purposeless and uncoordinated flailing of all four limbs, which was partially suppressible upon command, and was decreased during sleep. This became progressively erratic, often resulting in injuries owing to frequent knocking against the padded bed-railings. Administered oral lorazepam did not help. She was watched constantly for her safety.

Cerebrospinal fluid analysis and blood investigations were normal. Electroencephalography revealed generalized slow waves with no epileptiform activity. Magnetic resonance imaging (MRI) of the brain revealed bilateral symmetric T2 hyperintensity of the caudate and putamen nuclei, and mesial temporal lobes (Figure 1a).

Figure 1.

Brain MRI (FLAIR sequence): (a) on admission and (b) 8 weeks after admission.

She was referred to the psychiatric consultation-liaison service to help manage refractory episodes of restlessness. There were concerns as to the possibility of an underlying hyperkinetic movement disorder. Neuropsychiatric assessment revealed a young, disheveled, Chinese lady with fleeting eye contact. She was uncooperative, restless, and her speech laconic. Three-point orientation was intact, with no evidence supporting psychosis or catatonia.

The psychiatrists and neurologists jointly diagnosed her with movement disorder likely arising from post-inflammatory lesions in the basal ganglia. Low-dose olanzapine was started with good immediate effect. Upon discharge, her Montreal Cognitive Assessment (MOCA) was 18/30 with marked impairment in delayed recall, visuospatial functioning, repetition, and conceptualization. A month later, a repeat brain MRI revealed near-complete resolution (Figure 1b). She was asymptomatic, scored 29/30 in the MOCA, and had passed her final examinations.

At rest, the striatum is quiescent while the pallidum active, thereby inhibiting thalamic excitation of the motor cortex; these are modulated by the substantia nigra and subthalamic nucleus (Kiernan and Barr, 2005). Despite few reports on post-encephalitic movement disorders, there is an extensive literature on caudate infarcts associated with subsequent movement abnormalities (Kumral et al., 1999). Motor abnormalities occurred in two-thirds of patients with caudate infarcts, primarily in patients with lesions extending to the anterior limb of the capsule. Hemiballismus due to striatal lesions have also been described (Lownie and Gilbert, 1990; Srinivas et al., 1987).

Despite eventual resolution, urgent short-term interventions are warranted in view of the distress and possible danger. By blocking dopamine receptors, antipsychotics are recommended as first-line medication (Dewey and Jankovic, 1989). Non-pharmacological interventions include close nursing supervision, skin hygiene, high caloric nutritional support, fluids, an appropriate mattress and padded bed rails.

The transient nature of this patient’s symptoms demonstrated that damage to neostriatal tissue was not decisive in itself. With implications on management and prognosis, this warrants further study of the neuropsychiatric findings associated with the different caudate subnuclei.