Volume 16, Number 2
FROM THE JOURNALS
Brainwaves Offers a Sampling of Recent Journal Articles:
One drawback in understanding Rett syndrome (RTT), a neurodevelopmental disorder often mistaken for autism, is the inability to catalog its biology during its course. A study by SakkuBai Naidu, M.D., and colleagues shows, however, that sampling patients' nasal epithelium in a simple biopsy provides a window on the illness. Biopsies contain olfactory receptor neurons. In comparing tissue from RTT patients with controls, the researchers noted far fewer mature neurons.Those remaining were physically abnormal. The high numbers of immature neurons suggest a rise in neurogenesis with failure to mature.
Ann Neurol 2003;54(2):206-218.
Injuries to peripheral nerves are notorious for causing enduring pain. Common belief holds that nerve regeneration offers relief. James Campbell, M.D., and his team sought to verify that idea, using a control and two animal models of neuropathic injury-one with a ligature lesion and the other with a crush lesion, both at the L5 spinal nerve root in the rat. Nerves in the latter are more prone to regenerate. Rats were tested periodically for heightened sensitivity to mechanical and cooling stimuli. Later, tissues were examined histologically. Both models were hypersensitive to test stimuli. But, with time, differences between the two appeared in structure and in response, suggesting nerve regeneration may alleviate pain. This is a key step in understanding neuropathic pain. It implies that assisting nerve recovery may control it.
Neurosurgery 2003;53(5):1200-1204.
Literature suggests the MRI technique called fluid attenuation inversion recovery (FLAIR) may be superior to standard CT in detecting subarachnoid hemorrhage (SAH). That would be a boon because lumbar puncture holds a high risk for some patients. But a team of neuroradiologists including Mona Mohamed, M.D., and David Yousem, M.D., questioned FLAIR's superiority, comparing it to the gold standard for SAH-revealing-the lumbar puncture. An unbiased review of 12 patients with negative CT scans but positive lumbar puncture showed FLAIR within two days of the event didn't fare well: It concurred with the puncture in only two of the cases. The authors offer reasons why that might be the case.
Am J Neuroradiol in press.
Difficulty in pinning down the nature of bipolar patients' cycling between mania and depression is one of psychiatry's dilemmas. In "rapid cycling" patients, for example, is it that episodes are more frequent or is it the actual switching that's speeded up? Dean MacKinnon, M.D., Peter Zandi, Ph.D., J. Raymond DePaulo, M.D., and colleagues favor a closer look at the switching process, saying the phenomenon may clarify the biology of bipolar disorder. They've analyzed 608 people in a bipolar genetics study, including those who report rapid switching and those without it, to find possible influencing factors-things like onset age and antidepressant. Results showed those with earlier onset, those with substance abuse or anxiety disorder or those who've attempted suicide are more prone to rapid switching.
Arch Gen Psychiatry 2003; 60(9):921-934.
Disabling neuropathy is a major side effect of many chemotherapeutic drugs. Fortunately, for most chemotherapies, the highest dose that avoids neuropathy has been figured out. But a research team including neurologists Vinay Chaudhry, M.D., and John Griffin, M.D., suggests that such "safe" doses may not be safe in patients with pre-existing neuropathy. They report on six patients who received chemotherapy for cancers or lupus and who already had neuropathy from causes ranging from diabetes to alcohol use. All suffered significant worsening of their neuropathy at a "safe" dose of chemotherapy. Because such neuropathy can be irreversible and resulting pain can dramatically lower quality of life, careful monitoring of neuropathy-bearing patients undergoing "chemo" should be the rule. Neurology 2003;60:337-340.