Tongue scalloping: A novel clinical indicator in obstructive sleep apnea - An overlooked but insightful clinical sign

INTRODUCTION

Obstructive sleep apnea (OSA) is a common yet underrecognized sleep disorder characterized by repeated episodes of partial or complete upper airway obstruction during sleep. The global prevalence of OSA is increasing, particularly due to rising obesity rates and sedentary lifestyles.^[1] Timely recognition and intervention are critical in preventing its long-term complications, including systemic hypertension, pulmonary hypertension, type 2 diabetes mellitus, and stroke.^[2]

While polysomnography (PSG) remains the gold standard for diagnosis, it is expensive, time-consuming, and not widely accessible in all healthcare settings. Hence, there is a growing interest in identifying simple, non-invasive bedside signs that can help clinicians triage patients for sleep studies. Tongue scalloping is an under-recognised clinical sign on oral inspection [Figure 1] that can provide valuable insight into upper-airway anatomy and OSA risk.^[3]

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Figure 1:

Schematic line diagram illustrating tongue scalloping in obstructive sleep apnea.

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CLINICAL DESCRIPTION OF TONGUE SCALLOPING

Tongue scalloping, also referred to as lingua indentata, is defined by the presence of wavy, scalloped indentations along the lateral edges of the tongue [Figure 1]. These impressions are thought to result from chronic pressure exerted by the tongue against the inner surfaces of the molar teeth, typically due to tongue enlargement or spatial restriction in the oral cavity.^[4]

PATHOPHYSIOLOGICAL BASIS

Several anatomical and physiological mechanisms may explain the presence of tongue scalloping in OSA patients:

• Macroglossia: Enlargement of the tongue in obese or genetically predisposed individuals increases the likelihood of upper airway obstruction during sleep.^[5]

• Mandibular deficiency (retrognathia): A small or retruded lower jaw reduces space in the oral cavity, causing the tongue to press against the teeth and airway.^[6]

• Neuromuscular hypotonia: In OSA, reduced muscle tone during sleep allows the tongue to collapse posteriorly, further exacerbating airway obstruction.

• Airway crowding: Scalloping indicates a relatively large tongue in a small oral cavity, often correlating with higher Mallampati scores and narrowed oropharyngeal space.^[7]

CLINICAL SIGNIFICANCE AND DIAGNOSTIC IMPLICATION

Tongue scalloping is easily identifiable during a standard oral examination. It may serve as an important visual marker in patients suspected of OSA, particularly in primary care and resource-limited settings. Its presence correlates with a high apnea–hypopnea index on PSG [Table 1], increased body mass index, large neck circumference, and higher Mallampati class.^[3,6]

CONCLUSION

Tongue scalloping is a simple, quick-to-identify, and inexpensive clinical sign that can raise suspicion for OSA in outpatient and bedside settings. While it should not replace formal diagnostic tools, its utility lies in early recognition, triage, and heightened clinical suspicion, especially in high-risk individuals. Greater awareness among clinicians can enhance early diagnosis, leading to improved management outcomes in OSA patients.