Nightmares can seem very real at times, but then we wake up and realize it was all a bad dream. Now imagine having a vivid nightmare with all the reality of waking life and then... it turns out you're actually awake through it all!
This happened to an 11 year old Italian boy who reported frightening auditory and visual hallucinations of Voldemort, the archenemy of Harry Potter, for three straight days. These hallucinations began after a bout of sore throat and fever (38°C). As Vita et al. (2008) report:
The day after the resolution of fever, he began to present hallucinations. Hallucinations occurred in the afternoon, after watching TV. They were polymodal: he saw and heard Voldemort (an evil character of the Harry Potter saga). He did not realize his hallucinations were not real; he was extremely frightened, and he cried and searched his parents for protection. The episode lasted several hours, and was not associated with modification of vigilance or consciousness. ... Two days later, a new hallucinatory episode occurred: again, he saw Voldemort, who appeared threatening, and he fought against him. A further episode, with the same features, occurred the following day. He interacted with the characters of the hallucination, and on one occasion, he wore a sword and helmet to fight against Voldemort. When asked to recall the hallucinations, the boy said that they appeared real to him.
Neurological exam, EEG, and CSF cultures for bacteria, viruses, and fungi were all negative. CSF titers of antibodies were normal, and there was no evidence of autoantibodies. However, an MRI scan showed abnormal signs in the boy's brainstem. Several small lesions were observed in the pons, in the vicinity of a region implicated in REM sleep.
Fig. 1 (modified from Vita et al., 2008). MRI after the onset of hallucinations. Small areas of signal hyperintensity (lesions) are indicated by the arrows.
The etiology and phenomenology of the boy's condition seem consistent with peduncular hallucinosis, “a rare form of visual hallucination often described as vivid, colorful visions of people and animals.” The exact cause is unknown, but most cases have been related to lesions in the midbrain, thalamus, or brainstem (Dogan et al. 2013; Penney & Galarneau, 2014; Talih, 2013). In some instances the patients are aware that the hallucinations are not real, but other cases present as a psychiatric disorder and can include auditory or tactile hallucinations, in addition to visual.
Here, Vita et al. (2008) speculate that dreaming and REM sleep have become dissociated: the boy was literally dreaming while awake. Fortunately, his nightmarish condition disappeared after treatment with immunoglobulins. The exact diagnosis was unclear, but it might have been a transient demyelinating syndrome, which involves the loss of white matter, or myelin, that surrounds the axon.
The authors cited a model of REM sleep in which GABA-containing “REM-on” neurons inhibit GABAergic “REM-off” neurons located in the ventrolateral periaqueductal gray matter (vlPAG) and lateral pontine tegmentum (LPT), and vice versa.
Fig. 1 (modified from Vita et al., 2008). MRI after the onset of hallucinations. Three small lesions are indicated by the arrows.
Turns out the lesions (shown in gray stippling below) could include some of these neurons, especially those in the REM-off areas (vlPAG and LPT).
Fig. 1 (modified from Vita et al., 2008). Schematic of the REM-on and REM-off areas in the pons. Gray stippling indicates the lesions. REM-on region in black, REM-off regions in white.1
The authors speculated that transient dysfunction of REM-off cells, caused by the inflammatory demyelinating syndrome, resulted in weaker inhibition of REM-on cells, allowing a dream-like state to ooze into wakefulness.
Luckily the boy won out over Voldemort in the end, assisted by a team of doctors at Catholic University in Rome.
1 Detailed figure legend:
D: scheme of the REM-on and REM-off areas in the pons. In black: the REM-on region (locus subceruleus-α [sLCα]). In white: the REM-off region: ventrolateral periaqueductal gray (vlPAG) and lateral pontine tegmentum (LPT). In gray the REM modulatory regions: in rostrocaudal order, pedunculopontine tegmentum (PPT), laterodorsal tegmentum (LDT), dorsal raphe nucleus (DRN), and locus ceruleus (LC). Gray dotted areas: sites of the inflammatory lesions.
Dogan VB, Dirican A, Koksal A, Baybas S. (2913). A case of peduncular hallucinosis presenting as a primary psychiatric disorder. Ann Indian Acad Neurol. 16(4):684-6.
Penney L, Galarneau D. (2014). Peduncular hallucinosis: a case report. Ochsner J. 14(3):450-2.
Talih FR. (2013). A probable case of peduncular hallucinosis secondary to a cerebral peduncular lesion successfully treated with an atypical antipsychotic. Innov Clin Neurosci. 10(5-6):28-31.
Vita MG, Batocchi AP, Dittoni S, Losurdo A, Cianfoni A, Stefanini MC, Vollono C, Della Marca G, & Mariotti P (2008). Visual hallucinations and pontine demyelination in a child: possible REM dissociation? Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 4 (6), 588-90 PMID: 19110890
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