To evaluate the prevalence of anti-AQP4 antibody in serum and CSF samples from patients being investigated for possible neuromyelitis optica spectrum disorder (NMOSD) referred to the PathWest State reference laboratory using a sensitive cell-based assay (CBA). NMOSD is an inflammatory CNS disease distinct from MS, which is relatively rare in Western countries. A proportion of patients with NMOSD have detectable serum IgG antibodies that target the water channel aquaporin-4 (AQP4-IgG), but the frequency varies in different populations studied and according to the assay method employed. Sera or CSF from a diagnostic cohort of 196 consecutive patients with possible NMOSD which had previously been screened by indirect immunofluorescence (IIF) on primate cerebellum were re-tested for AQP4-IgG reactivity to the M1 and M23 isoforms of AQP4 using a commercial CBA. A control group of 205 patients with definite MS was also included in the study. Of the 196 patients, only 5 sera were AQP4-IgG positive, representing 2.6% of patients in the diagnostic cohort. All 5 AQP4-IgG positive patients fulfilled the 2015 revised diagnostic criteria for NMOSD and were females of varied ethnic origins, 4 of whom had longitudinally extensive transverse myelitis. The CBA confirmed AQP4-IgG positivity in the four patients previously reported as positive by IIF, and an additional patient with NMOSD who had previously been diagnosed as MS was also identified. None of the 205 MS sera were AQP4-IgG positive. Our study confirms the utility and greater reliability of the M1/M23 CBA for detecting AQP4-IgG in patients with possible NMOSD, and indicates a prevalence of seropositive NMOSD in the Western Australian population similar to that in other Western populations.
We have previously shown that following a period of unimanual fatiguing exercise, there is a reduction in primary sensorimotor cortex (SM1) activation with movement of either the fatigued or the non-fatigued hand by Benwell et al. (Exp Brain Res 167:160-164, 2005). In the present study we have investigated whether this reduction is confined to motor areas or is more widespread. Functional imaging was performed before and after a 10-minute fatiguing exercise of the left hand (30% of maximum handgrip strength) in seven normal subjects (4 M, mean age 25 years). The activating task was a handgrip against a low resistance (1 kg) in response to a visual cue (chequerboard reversal every 2 +/- 0.5 s). We compared activation in SM1, supplementary motor area (SMA), cerebellum (CB) and primary visual cortex (V1) before and after the fatiguing exercise. After exercise, contralateral SM1 activation was reduced by 33% (P < 0.05) compared to baseline for the fatigued hand and by 49% for the non-fatigued hand (P < 0.05). A similar pattern was seen for the bilateral SMA and ipsilateral CB following exercise (45 vs. 50% for SMA; 30 vs. 35% for CB; fatigued versus non-fatigued). Activation was also reduced in V1 but to a lesser extent than in motor areas (19 vs. 24%; fatigued versus non-fatigued). These results show that although the reduced functional activation during the recovery period after fatiguing exercise is more marked in motor areas, it also extends to non-motor areas such as the visual cortex, suggesting that there are more widespread changes in cerebral haemodynamic responses after fatigue.
Early electrophysiological studies during sensory stimulation in the anesthetized cat and more recent functional imaging studies during voluntary movement in humans have provided evidence for two separate representations of the body in the anterior and posterior lobes of the cerebellum; however, the functional role of these body maps in motor and sensory processing is not known. The aims of the present study were to determine whether this dual representation is also present during passive movement, and to compare the pattern of activation with that obtained during voluntary movement. Functional MRI measurements were undertaken in 14 subjects who performed right index finger flexion and extension movements at approximately 1 Hz, or had their finger moved passively at the same rate and through the same angle using a pneumatic device. During passive movement, dual activation was detected in the ipsilateral cerebellum, in the anterior lobe, and in the posterior lobe. A similar pattern of activation was observed during voluntary movement; however, the overall magnitude was about doubled. These data provide evidence for a dual ipsilateral representation of the hand in the rostral and caudal cerebellar cortex during passive as well as voluntary movements, with the rostral representation being the dominant one, and indicate that both of these areas are involved in kinesthetic sensory and motor processing.