Incidence of temporal thumb sign in adult patients with idiopathic seizures with and without elevated opening cerebrospinal fluid pressure.

objectivesThe temporal thumb sign (TTS) has emerged as a potential distinct magnetic resonance imaging (MRI) finding in pediatric patients with new-onset idiopathic seizures which is characterized by the protrusion of the inferior temporal gyrus into the skull base. This study investigated the prevalence and clinical implications of TTS in adult patients with idiopathic seizures, with or without elevated opening cerebrospinal fluid (CSF) pressure, and those diagnosed with idiopathic intracranial hypertension (IIH) without seizures. MATERIALS AND

methodsA retrospective study was conducted on 157 adults aged 18-40-years-old, divided into four distinct groups. Group 1 consisted of 52 patients diagnosed with idiopathic intracranial hypertension (IIH) without seizures. Group 2 included 27 patients with seizures and elevated opening CSF pressure. Group 3 comprised 39 patients with seizures but normal opening CSF pressure. Group 4 consisted of 39 controls. MRI or CT scans and lumbar puncture data were analyzed to evaluate the presence of TTS. Statistical analysis was performed to assess the prevalence, sensitivity, and specificity of TTS across groups. Significant differences were defined as p < 0.05.

resultsSignificant differences in TTS prevalence were observed between all groups (p < 0.001). TTS was most frequently detected in patients with seizures and elevated opening pressure (92.6%), followed by IIH patients without seizures (63.5%), and patients with seizures and normal opening pressure (61.5%). The control group exhibited a lower frequency of TTS (12.8%). Logistic regression demonstrated the association of TTS with seizure and elevated intracranial pressure (p < 0.001). Inter-rater reliability analysis showed excellent agreement between observers.

conclusionsThe results of this study suggest that the Kamali "Temporal Thumb Sign" is a novel neuroimaging feature associated with seizures and elevated opening CSF pressure in adult patients. High sensitivity (92.6%) of the TTS may yield it as a screening imaging marker in either brain CT or MRI scans in the emergency department, which could aid in suspecting possible elevated opening CSF pressure and proceeding with further workup. The association of TTS with seizures suggests a potential link between elevated intracranial pressure and structural alterations in the skull base with seizure presentation. The TTS may represent a distinct manifestation of intracranial hypertension, similar to temporal lobe encephaloceles. KEY POINTS: Question This study investigates the prevalence and clinical implications of TTS in adults with idiopathic seizures at a single institution. Findings TTS was detected in 92.6% of patients with seizures and elevated CSF pressure. Clinical relevance TTS may serve as a sensitive marker for identifying elevated intracranial pressure in patients presenting with seizures to the emergency department.