Ms L: a case of a reversible phenotypic and brain function equivalent of frontotemporal dementia.

Frontotemporal dementia (FTD) is second only to Alzheimer's disease in individuals younger than 65 years of age. Behavioral variant FTD (bvFTD) presents with nonspecific symptoms such as disinhibition, apathy, or emotional blunting. Although neuropsychological testing and structural neuroimaging are not very helpful in diagnosing bvFTD in its initial stages, newer quantitative structural methods and functional neuroimaging have better sensitivity and specificity. Ms L presented with blunted affect, disinhibition, impairments in insight, planning ability and social comportment, changed dietary habits, and episodes of mutism. Her brain magnetic resonance imaging was normal whereas her single-photon emission computed tomography (SPECT) pattern was consistent with FTD. Her clinical presentation was consistent with bvFTD yet both the symptoms and SPECT findings reversed after 2 years of follow-up. We suggest that Ms L had a reversible phenotypic and brain function equivalent of bvFTD. The case highlights the limitations of our diagnostic tools and the complex relationship between clinical symptoms, neuroimaging, and etiology.

SPECT brain imaging in chronic Lyme disease.

OBJECTIVES: Lyme disease is an infectious disease that frequently involves the central nervous system, leading to cognitive and/or mood dysfunction. The basis for these symptoms remains to be defined but may be the result of a vasculitis or metabolic abnormality secondary to the infection. SPECT scans of the brain might provide an objective measure of abnormalities present in patients with otherwise difficult to objectify clinical findings. The objective of this study was to determine the frequency, location, and severity of abnormalities in SPECT scans of the brain of patients with chronic Lyme disease. METHODS: A total of 183 individuals who met the clinical definition of chronic Lyme disease underwent SPECT scanning of the brain using Tc and standard nuclear imagine techniques. Abnormalities of perfusion to affected areas of the brain were defined as mild, moderate, or severe. RESULTS: Of all patients, 75% demonstrated abnormalities in perfusion to various areas of the brain, most notably the frontal, temporal, and parietal lobes. Patients considered to be seropositive and those considered seronegative had similar rates, types, and severity of perfusion defects. Abnormalities of MRI of the brain were seen in 14% of patients. Treatment with antibiotics, especially those with intracellular-penetrating activity, resulted in resolution or improvement of abnormalities in 70% of patients over a 1- to 2-year period. CONCLUSIONS: Brain SPECT scans are abnormal in most patients with chronic Lyme disease, and these scans can be used to provide objective evidence in support of the clinical diagnosis. The use of certain antibiotic regimens seems to provide improvement in both clinical status and SPECT scans.

A study comparing SPECT and MRI in patients with anosmia after traumatic brain injury.

PURPOSE: The initial or first clinical presentation of altered sensation of smell is directly linked to the degree of impaired sensitivity. We took the opportunity to examine normal and nonspecific MRI findings in 6 patients with known anosmia after traumatic brain injury with perfusion SPECT brain imaging. MATERIAL AND METHODS: Patients included those with primary loss of smell after head injury. All patients underwent standard testing by the Taste & Smell Center. Normal or nonspecific near normal brain MRI studies were subsequently referred for SPECT perfusion neuroimaging. RESULTS: MRI studies were negative in 3 cases. In the remaining studies, one case showed nonspecific white matter change, another low signal in the left frontal gyrus, and the sixth case merely some cortical atrophy. All 6 cases demonstrated lesions on SPECT involving the frontal, temporal, and temporoparietal cortex. CONCLUSION: This study identified altered blood perfusion pattern in otherwise normal anatomic structures on MRI.

Migration of Tc-99m DTPA from the cerebral ventricle to the subarachnoid space.

A 70-year-old woman was examined because of increasing problems with cognition. She had a history of a cerebral shunt placed surgically 10 years previously. Introduction of Tc-99m DTPA directly into the ventricular cavity revealed good ventricular distribution, followed by progression downward, as though into a previous ventriculoperitoneal shunt. However, a chest radiograph revealed what appeared to be a shunt tube in the right atrium. Delayed lateral images showed activity in proximity to the vertebral column, indicating migration of tracer and cerebrospinal fluid into the dorsal and lumbar subarachnoid space.