Dear Editor,

Moyamoya angiopathy (MMA) is a chronic progressive occlusive intracranial vasculopathy characterized by angiographic findings of stenosis or occlusion at the terminal portion of the internal carotid artery (ICA) or proximal anterior cerebral artery (ACA) and/or middle cerebral artery (MCA) with compensatory collateral vessels at the base of the brain [1]. Previously considered to affect predominantly persons of Asian heritage (particularly Japanese), recent evidence suggests MMA is not uncommon, affecting individuals of many ethnic backgrounds throughout the world, including American and European populations. It is known to present with myriad of nonparetic symptoms. Seizures can account for 10.5% presenting symptom in MMA; various seizure types including focal seizure with or without secondary generalization, generalized seizure and febrile seizure may be seen. However, to the best of our knowledge, wandering in sleep is unheard of as a presenting and sole manifestation of MMA [2]. We herein present an index case of MMA in a young female unmasked during evaluation of walking in sleep.

A 16-year-female, initially evaluated by primary-care physician, sought our care with parents complaining of infrequent (2–3/year) episodes of wandering in sleep for last 6 years. On detailed query, the episodes lasted for 4–5 min with the patient getting up from sleep and walking around in the room, mumbling incomprehensible words with twitching around the angle of the mouth and finally returning to her bed, while regaining consciousness but remaining confused. This episodes used to occur at midnight or early morning, usually 4–5 h after falling asleep. There was no similar history in the family. Neurological examination revealed no significant abnormality.

Routine blood investigations were normal. Nocturnal video-electroencephalogram (EEG) and polysomnography (PSG) testing were unrevealing. Magnetic resonance imaging (MRI) brain showed multiple flow voids around the basal ganglia leading to a suspicion of chronic vaso-occlusive disease which was confirmed in MR angiography that revealed a bilateral terminal ICA steno-occlusive lesion with multiple collaterals suggestive of MMA. Positron emission tomography with computed tomography (PET-CT) indicated severe hypometabolism of bilateral mesial temporal lobe and hypermetabolic cingulate cortex (Fig. 1). Detailed evaluation for secondary causes of MMA was non-contributory.

Fig. 1
figure 1

MRI brain T2 sequence shows multiple flow voids around the basal ganglia in both the cerebral hemisphere (A) and MR angiography shows bilateral terminal ICA stenosis with non-visualization of MCA, proximal ACA with multiple collaterals appearing as “puff of smoke” (B). PET-CT showing hypometabolism in bilateral mesial temporal lobe (C)

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Parents refused to any invasive investigation or therapy. Hence, the patient was managed conservatively with antiplatelet and anti-epileptic (oral oxcarbazepine) therapy, considering it to be an episodic nocturnal wandering in temporal lobe epilepsy. The patient has been under our follow-up for last one and half years without any reports of similar episodes or other new onset fixed or transient neuro-deficits.

Parasomnias and epileptic seizures have been known to cause abnormal paroxysmal events in sleep. NREM parasomnias like sleep-walking usually occur in the earliest sleep cycle, in NREM sleep, lasting for several minutes or longer, with the patient usually returning to bed at the end of the event. Episodic nocturnal wandering due to seizure, however, can occur at anytime throughout the night, often in stage 1/2 of NREM sleep, usually lasting less than 2 min, with the patient often not returning to bed at the end of the event. The presence of awakening, vocalization, automatism and post-ictal phenomenon is more commonly noticed in episodic nocturnal wandering than in sleep-walking [3, 4].

Both frontal and temporal origin seizures have been noted with episodic nocturnal wandering. In comparison to frontal lobe epilepsy, seizures in nocturnal temporal lobe epilepsy are less frequent, non-clustered and lack hyperkinetic activity, complex motor automatism with tonic contraction and have fewer positive family history [3]. Our patient with shorter duration, vocalization, automatism and confusion following ictus suggested a diagnosis of a seizure, further corroborated by responsiveness to anti-epileptic therapy. An infrequent, non-clustered attack, without complex automatism and tonic contraction pointed towards a temporal lobe origin nocturnal seizure in our case.

While video-EEG-PSG is considered the “gold standard” investigation, in situations of infrequent events, it may fail to generate conclusive evidence towards the diagnosis as was seen in our case. In such a setting, it is the elicitation of meticulous history that helps to arrive at a correct diagnosis [3].

The cingulate cortex as a part of functional network is known to modulate behaviors in emotional processes and, through the hippocampus and para-hippocampus, constitutes a bridge between the temporal and frontal lobe. It has been shown to be hyperperfused in both nocturnal frontal lobe seizure and sleep-walking, possibly responsible for the generation of the complex motor behavior during sleep [5]. Our case also demonstrated cingulate hypermetabolism possibly accounting for the wandering in sleep following the temporal origin ictus.

Moyamoya can present with a wide array of non-motor paretic symptoms, posing a great diagnostic dilemma to the physician [2]. A low index of suspicion and increased awareness of the rarer presentations of this rather uncommon disease can greatly aid in early diagnosis, management and favorable prognosis.