PMC3347913_01
Magnetic resonance imaging (MRI) showing an abnormal increase in signal intensity in parts of the cerebral cortex (upper left), subcortical gray matter (upper right), and cervical cord (lower left). There is also increase in signal in the left neck muscles (lower right; arrow).
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Repeat MRI on the fifth hospital day showed increased signal in the brain, cervical cord, and neck muscles (Fig. 1).
Scalp electroencephalogram (EEG) showing continuous generalized slowing and periodic discharges. This abnormal pattern is seen in the EEG of patients with widespread cerebral dysfunction, often due to an underlying encephalopathic or encephalitic process.
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Electroencephalography (EEG) showed diffuse slowing and periodic discharges (Fig. 2).
Nerve conduction studies (NCS) showing inexcitable left median and ulnar nerves with stimulation at the wrist and elbow, absence of response of the left peroneal nerve with stimulation at the ankle, and low-amplitude compound muscle action potential (CMAP) with stimulation of the left peroneal nerve below the fibular head (see table above). Only two tracings are shown: left median nerve stimulation at the wrist (left tracing) and left peroneal nerve stimulation below the fibular head (right tracing).
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Left peroneal nerve stimulation below the fibular head produced low- amplitude CMAPs with normal latency (Fig. 3).
Neuropathological findings: (A) Section of the left brachial plexus demonstrating focal destruction of myelin (long arrows) and occasional monocytes (short arrows) [toluidine blue and basic fuschin, 400X]. (B) Electron micrograph of a left brachial plexus nerve showing histiocytes (monocytes) filled with phagocytised and degraded myelin (long arrows); lymphocytes are occasionally present (short arrow) [uranyl acetate and lead citrate, 3520X]. (C) Cortical meninges with moderate lymphocytic infiltrate (arrows) extending into the underlying cortex (arrowhead) [toluidine blue, basic fuschin, 400X]. (D) Neuron containing sharply demarcated round to oval eosinophilic cytoplasmic inclusions known as Negri bodies (arrows). Note scant inflammation in the background [hematoxylin and eosin, 400X].
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Postmortem histological examination of the left brachial plexus demonstrated loss of axons, degeneration of myelin, and an accompanying monocytic infiltrate (Fig. 4A). No viral particles were identified (Fig. 4B). Histological examination of the brain showed moderate lymphocytic infiltrate within the meninges with extension to the underlying cortex, indicating meningoencephalitis (Fig. 4C). Negri bodies were also detected in the cerebral cortex (Fig. 4D).