Brain magnetic resonance imaging findings suggestive of widespread white matter involvement in children with Streptococcus mitis meningitis.

Streptococcus mitis (S. mitis) is a rare cause of meningitis in immunocompetent children. It has been described in patients with neurosurgical procedure, previous spinal anesthesia and immunodeficiency. We report two childhood cases of S. mitis meningitis. The children were previously healthy. One of the patients had poor oral hygiene and the other had a history of sinusitis. Both of them had encephalopathy and signs of meningeal irritation at presentation. Widespread cerebral white matter lesions were found on brain magnetic resonance imaging. The lesions disappeared and encephalopathy recovered with antibiotic and immunomodulatory treatment.

Diffusion-weighted imaging in brain aspergillosis.

Brain aspergillosis is a rare pathology, occurring mainly in immunocompromised patients, responsible for multiple cerebral septic infarctions. Some researchers have described magnetic resonance (MR) findings in cerebral invasive aspergillosis, but diffusion-weighted imaging (DWI) has rarely been reported, especially in typical non-enhancing lesions, while it may be helpful for early differential diagnosis and may allow earlier antifungal treatment. We describe three cases of patients presenting brain aspergillosis, with MR imaging including diffusion-weighted sequences and apparent diffusion coefficient (ADC) cartography. The three patients described in this study presented a total of 23 circular lesions, and one patient presented an infarction area in the territory of the right middle cerebral artery. Lesions were ring-enhancing for one patient, and presented no enhancement for the other two. Eleven lesions were very bright on DWI, with reduced ADC values. Twelve lesions, either enhancing or not enhancing, presented a 'target-like' aspect with central and peripheral hypointense areas on DWI, corresponding to higher ADC value areas, and intermediate marked hypersignal on DWI. This typical aspect of aspergillosis lesions on DWI may allow early diagnosis and treatment of cerebral aspergillosis, and is helpful for differentiating aspergillosis lesions from other infectious or malignant lesions affecting immunocompromised patients.

Electron microscopic findings of the peripheral nerve lesions of nude mice inoculated with M. leprae.

Peripheral nerve lesions of nude mice inoculated with Mycobacterium leprae were examined from 1 year to 1 year and 8 months post-inoculation. Leprosy bacilli and intracytoplasmic foamy structures were found in the perineurial cells, endothelial cells of capillaries, Schwann cells, and axons of the myelinated nerve fibers inside the lepromas of foot pads. In the proximal portion of the sciatic nerve, bacilli were found chiefly in the macrophages of the endoneurial space. Bacilli were not found in the perineurial cells of the sciatic nerves. Marked fibrosis, hypertrophy or degeneration of Schwann cells, demyelination, axonal damage or irreversible destruction of nerve architecture were not observed clearly. Therefore, it is thought that nude mice inoculated with M. leprae are suitable models for the study of the early peripheral nerve lesions of lepromatous leprosy.

Detection of Borrelia burgdorferi DNA and complement membrane attack complex deposits in the sural nerve of a patient with chronic polyneuropathy and tertiary Lyme disease.

We report a patient who developed a chronic sensory-motor polyneuropathy and a progressive myelopathy 4 years after a tick bite. An increased serum antibody titer to Borrelia burgdorferi suggested a diagnosis of Lyme neuroborreliosis, although a concomitant cervical spondylosis probably contributed to spinal cord damage. Treatment with ceftriaxone resulted in a marked improvement of neuropathic symptoms, providing indirect evidence of spirochetal infection. Search for B. burgdorferi DNA by polymerase chain reaction amplification on sural nerve confirmed the diagnosis, demonstrating that the spirochete localized in the peripheral nervous system. The presence of complement membrane attack complex deposits and macrophage infiltrates around epineurial vessels and within the endoneurium suggests that the neuropathy in our patient was immune-mediated.