Isolated Right Temporal Lobe Stroke Patients Present with Geschwind Gastaut Syndrome, Frontal Network Syndrome and Delusional Misidentification Syndromes

Background: Right temporal lobe lesion syndrome elicitation presents a clinical challenge. Aside from occasional covert quadrantanopias, heralding elementary neurological deficits are absent. Aim: Isolated right and left temporal lobe stroke patients were analyzed for the panoply of known temporal and frontal cognitive and neuropsychiatric syndromes. Methods: Temporal lobe stroke patients were analyzed, derived from a dedicated cognitive stroke registry. Patients were screened by a validated bedside cognitive battery and a neuropsychological test battery, including the Bear Fedio Inventory for diagnosis of the Geschwind Gastaut (GG) syndrome, frontal network syndrome testing (FNS), emotional intelligence testing and delusional misidentification syndromes (DMIS). NIH stroke scores were documented and lesion location identified with the 3 dimensional digitized Cerefy coxial brain atlas. Exclusions were coma, encephalopathy and medication related effects. Results: Of 2389 patients analyzed, in patients with isolated right temporal lobe (IRT) stroke (n = 5, infarcts n = 3, hemorrhage n = 2), the GG syndrome and FNS were present in all five. Other relatively frequent syndromes included DMIS in 4, visuospatial dysfunction in 2 and amusia in 2. No patient had a NIHSS greater than 1. The only elementary neurological sign was quadrantanopia in 3 patients. Lesion location was mid and lateral temporal lobe (n = 2), middle and mesial temporal lobe (n = 1) middle temporal lobe (n = 1) and lateral temporal lobe (n = 1). Comparison with isolated left temporal lobe (ILT) stroke revealed syndromes of aphasia (n = 4), alexia (n = 2), acalculia (n = 2), agnosia (n = 2), verbal amnesia (n = 1), none of which occurred in the IRT patients. The mean NIHSS scores of IRT (0.6) and ILT strokes (4.2) was different (t = 2.23, p = 0.04). The 2 × 8 Fisher Exact Test revealed significant differences for the clusters of syndromes occurring in the right and left isolated temporal lobe lesions (p = 0.00002). Conclusion: The GG syndrome, FNS and DMIS are prominent syndrome constellations in stroke patients involving the right temporal lobe and constitute the neurological deficit without heralding long tract signs. By extrapolation these syndromes may also be present in the general right hemisphere lesion population.