Correlation of FDG PET Hypometabolism with Interictal Spike Frequency during FDG Distribution Phase in Temporal Lobe Epilepsy

BACKGROUND: Although hypometabolism of positron emission tomography (PET) helps lateralization of epileptic focus in temporal lobe epilepsy (TLE), the mechanism of PET hypometabolism (PET-Hypo) is still controversial. We investigated whether interictal spike frequency during distribution phase of 18F-fluorodeoxyglucose (DP-FDG) correlates with the degree of PET-Hypo in TLE. METHODS: FDG PET was performed in 21 TLE patients. In PET, polar, mesial, anterior, middle and posterior temporal ROIs (region of interests) were determined in superior, middle and inferior transtemporal planes. PET Asymmetry index (AI) of each ROI was obtained by (right-left)/(right+left) x 2. Scalp EEG was recorded from 30 min prior to FDG injection until the end of scanning. Interictal spikes on temporal electrodes (F7, F8, FT9, FT10, T3, T4, T5 and T6) were counted during DP-FDG. Left-Right difference of spike numbers on electrodes of both temporal regions was obtained by subtracting spike number of right temporal region from that of left side. RESULTS: Average number of interictal spikes during FDG-DP was 11.5 per patient. Distributions of spikes were anterior temporal (F7, F8, FT9, FT10):70.7%, mid-temporal (T3,T4):29.3%, posterior temporal (T5,T6):0%. Left-Right difference of spike number was strongly correlated with PET AI of whole temporal region (r=0.655, p=0.002). Lateralization of all PET-Hypo was concordant to that of interictal spike dominance during DP-FDG although 2 cases showed false lateralization of epileptic focus by PET. CONCLUSIONS: FDG PET hypometabolism was significantly correlated with DP-FDG interictal spike numbers. Anterior and polar temporal regions showed the best correlation. PET-Hypo may reflect not only permanent functional deficit but also transient regional cerebral dysfunction.

Solitary Plasmacytoma associated with Peripheral Neuropathy

Solitary plasmacytoma, in contrast to the disseminated neoplastic proliferation of plasma cells with marked infiltration of multiple organ system in multiple myeloma, is plasma cell neoplasm of a single focus occuring either in bone or soft tissue. The association between a solitary plasmacytoma and peripheral neuropathy is rare, and it is a progressive sensorimotorneuropathy, with a raised CSF protein and mixed demyelination and axonal loss in nerve biopsy. Localized radiotherapy indeed proves to be effective of not only arresting the progress of the neuropathy but also allowing a degree of recovery. We experienced a 55-year-old male with a solitary plasmacytoma and peripheral neuropathy confirmed by the radiologic studies, immunohistochemical stain of nasopharyngeal mucosa biopsy and sural nerve biopsy, which has loss of myelinated fiber and axonal degeneration. Until now, the reported cases are very rare in Korea, so we presented a case of solitary plasmacytoma associated with peripheral neuropathy.

Two Fatal Cases due to Porphyric Peripheral Neurophathy

We report two cases of porphyric peripheral neuropathy in a 19-year-old male with variegate porphyria and in a 39 year-old male with intermittent acute prophyria. Clinically, there were sensory, motor disturbance and autonomic symptoms including decreased sweating, urinary and sphinctor distrubances. Variegate porphyria showed facial diplegia and positive family history inherited by autosomal dominent trait. Intermittent acute porphyria was combined-with SIADH. Both cases were expired due to respiratory failure. Nerve conduction studies were carried out in two cases and both cases showed slow motor, sensory nerve conductlon velocity ,and significant low CMAPs(Compound Muscle Action Potentials). Sural nerve biopsy was carried out in a variegate prophyria compared with one normal control. Decreased large myelinated fibers was found. In nerve fiber teased study. 8.5% of nerve fibers showed axonal degenration and only 2.3% of the segmental demyelination. There findings are suggesting that the porphyric neuro might be the axonal type.and severe neuropathy in a sign of poor prognosis.