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Table of Contents    
Year : 2020  |  Volume : 68  |  Issue : 6  |  Page : 1486-1487

”Spontaneous” Snout: A Frontal Release Phenomenon

1 Department of Neurosurgery, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India
2 Department of Neurology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

Date of Web Publication19-Dec-2020

Correspondence Address:
Dr. Madhivanan Karthigeyan
Department of Neurosurgery, PGIMER, Sector 12, Chandigarh - 160 012
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.304119

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How to cite this article:
Karthigeyan M, Salunke P, Takkar A. ”Spontaneous” Snout: A Frontal Release Phenomenon. Neurol India 2020;68:1486-7

How to cite this URL:
Karthigeyan M, Salunke P, Takkar A. ”Spontaneous” Snout: A Frontal Release Phenomenon. Neurol India [serial online] 2020 [cited 2021 Jan 25];68:1486-7. Available from:


A 55-year-old man with ruptured distal anterior cerebral artery aneurysm [Figure 1]a underwent clipping through the basal interhemispheric approach. Despite sufficient maneuvers for adequate brain relaxation, significant brain bulge was noted and bifrontal retractors were placed to gain exposure to aneurysm. On postoperative day 2, he developed vasospasm with left hemiparesis for which intra-arterial nimodipine was administered. Noticeably, he also developed spontaneous, involuntary, and repetitive perioral movements with intermittent pouting of lips [Video 1]. There was no associated alteration in sensorium, facial deviation, or abnormal movements of any other site. Transient improvement on distraction was noted and the patient was able to partly suppress the movements on command. No epileptiform discharges were noted on electroencephalography. The computed tomography of head demonstrated infarcts in the frontal lobe and basal ganglia [Figure 1]b. The abnormal movements subsided at discharge and subsequently disappeared at 3-months follow-up.
Figure 1: (a): Cerebral CT angiography (sagittal view) shows distal anterior cerebral artery aneurysm (yellow arrow). (b): Axial plain CT reveals small patchy infarcts in the frontal lobe and basal ganglia (yellow arrows)

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The described movements were recognized as the variants of frontal release phenomenon. The other differential diagnosis with such clinical presentations could be orofacial dyskinesia, which is usually the long-term adverse effects of neuroleptics (D2 receptor blocking agents). However, no history suggestive of any implicating medication could be elicited.

Frontal release signs are the reappearance of primitive reflexes that normally disappear with brain maturation. Grasp, snout, and palmomental reflex are some of them and may be seen secondary to brain injury and metabolic and neurodegenerative brain disorders. They indicate diffuse frontal lobe dysfunction. At times, the early appearance of these signs may aid in predicting dementia and cognitive decline in patients with acquired frontal dysfunction.[1] Corticobulbar involvement is implicated in their pathogenesis.

In contrast to the usual snout reflex which needs to be elicited by tapping the upper lip, the patient presented here showed spontaneous pouting movements. The report highlights the same. The described phenomenon could be a useful clinical sign of frontal lobe disease. Diffuse damage, degenerative process, trauma, and tumors of bilateral frontal lobe may also cause the above phenomenon. Excessive frontal lobe retraction or vasospasm with frontal lobe infarcts possibly explains the abnormal movements in this patient.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Di Legge S, Di Piero V, Altieri M. Usefulness of primitive reflexes in demented and non-demented cerebrovascular patients in daily clinical practice. Eur Neurol 2001;45:104-10.  Back to cited text no. 1


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