Associations between autonomic dysfunction and pain in chemotherapy-induced polyneuropathy.

BACKGROUND: Autonomic neuropathy, a relatively common complication of several chemotherapy agents, can affect the vagus nerve and its pain inhibitory capacity, thus increasing sensitivity to pain. This study aimed to evaluate the relationships between autonomic parasympathetic function and the perception of (1) spontaneous pain; (2) experimental non-painful sensations; and (3) experimental painful sensations in chemotherapy-induced neuropathy patients. METHODS: Twenty-seven cancer patients with chemotherapy-induced polyneuropathy were enrolled (20 women, age 56.6 ± 7.9). Autonomic parameters of heart rate variability, deep-breathing and Valsalva ratios, experimental non-painful parameters of warm, cold and mechanical detection thresholds, and painful parameters of heat pain thresholds, pain rating of suprathreshold stimulus, mechanical temporal summation and conditioned pain modulation response were examined. RESULTS: Autonomic parameters and spontaneous pain levels were not associated, yet autonomic parameters were positively correlated with non-painful sensations - milder autonomic neuropathy was accompanied by milder sensory neuropathy as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher warmth detection threshold (r = -0.465; p = 0.033). Autonomic parameters were, however, negatively correlated with painful sensations - lower parasympathetic-vagal activity was associated with higher pain sensitivity as indicated by several parameters, e.g., lower Valsalva ratio was correlated with higher pain rating of suprathreshold stimulus (r = -0.559; p = 0.008). CONCLUSIONS: Diminished vagal function due to neuropathy is associated with, and may possibly underlie, pain disinhibition expressed as greater levels of experimental pain.

Primary osteogenic sarcoma arising from the dura mater: case report.

A 42-year-old woman who sought treatment for left drop foot was found to have a right frontoparietal parasagittal mass. Gross total resection of the tumor was performed and pathologic analysis revealed high grade osteoblastic osteosarcoma. The patient received adjuvant chemotherapy and continues to do well with no evidence of metastases or local recurrence 3 years after initial presentation.

A rare event of 5-fluorouracil-associated peripheral neuropathy: a report of two patients.

5-Fluorouracil (5-FU) is known to cause multifocal cerebral demyelination, which is pathologically related to a central inflammatory demyelinating process. To date, no case of peripheral neuropathy has been described after the administration of 5-FU alone. The authors describe two patients who had peripheral neuropathy that developed while they were receiving 5-FU-based chemotherapy.

Utility of relative cerebral blood volume mapping derived from perfusion magnetic resonance imaging in the routine follow up of brain tumors.

It was recently demonstrated that imaging of brain tumors by relative cerebral blood volume (CBV) maps reconstructed from dynamic magnetic resonance (MR) data provide similar diagnostic information compared to positron emission tomography (PET) or 201Tl single-photon emission computerized tomography (201Tl-SPECT) scans. The authors used relative CBV mapping for routine follow-up evaluation of patients with brain tumors and compared its sensitivity to diagnostic MR imaging, 201Tl-SPECT and clinical assessment. Fifty-nine patients were prospectively followed using 191 concomitant studies of dual section relative CBV maps, MR imaging, 201Tl-SPECT, and neurological evaluations. Studies were repeated every 2 to 3 months (median three evaluations/patient). The relative CBV maps were graded as relative CBV 0 to 4, where Grades 3 and 4 are indicative of proliferating tumors (four = rapid leak). There were 44 high-grade and 15 low-grade tumors followed during treatment. During the follow-up period a change in relative CBV grade was observed in 56% of the patients, revealing an increasing grade in 72% of them. The rapid leak phenomenon was detected in 35% of all studies and in 81% of those with a worsening relative CBV grade. Tumor progression was detected earlier by relative CBV maps as follows: earlier than MR imaging in 32% of the studies (earlier by a median of 4.5 months; p < 0.01); earlier than 201Tl-SPECT in 63% (median 4.5 months; p < 0.01), and earlier than clinical assessment in 55% (median 6 months; p < 0.01). In 82% of studies with positive MR imaging but negative 201Tl-SPECT, the lesions were smaller than 1.5 cm. The relative CBV maps clearly delineated the appearance of rapid leak in these lesions. Routine use of relative CBV maps that can be implemented on any high-field MR unit and added to the regular MR evaluation provides useful functional information in patients with brain tumors. When used as an adjunct follow-up evaluation it proved more sensitive than the other modalities for early prediction of tumor growth. It is very sensitive to small regional changes, unlike functional imaging such as PET or SPECT scans. Based on previous experience with 76 regional CBV studies, the authors conclude that regional CBV mapping correlates with active tumor and it may separate enhancing scar and radiation injury from infiltrative tumor. A new effect named the rapid leak phenomenon was also observed; this phenomenon, as identified on the regional CBV maps, correlates with high malignancy.

The effect of vigabatrin on central nervous system oxygen toxicity in rats.

The toxicity of hyperbaric oxygen in the central nervous system is expressed by clinical and electroencephalographic (EEG) manifestations resembling those of generalized tonic-clonic seizures. In the search for drugs effective against these seizures, we tested vigabatrin, an irreversible inhibitor of GABA (gamma-aminobutyric acid) transaminase. Five different doses of vigabatrin (ranging from 50 to 500 mg/kg) or vehicle were injected i.p. in rats implanted with cortical electrodes, 4 h prior to exposure to 5 ATA (0.5 MPa) oxygen. EEG and spectral analysis of the background EEG activity were monitored for the different dosages of the drug. The duration of the latent period before the appearance of electrical discharges in the EEG was used as an index of oxygen toxicity. The protective effect of vigabatrin was dose-related, and complete protection against hyperoxic-induced discharges was at 180 mg/kg. The protective effect lasted 24 h and decreased gradually disappearing completely on the third day. An increase in the low frequency bands of the EEG and a decrease in the faster activity were correlated with the vigabatrin dosage injected. Our results suggest that vigabatrin has the potential of being a useful drug in the treatment and prevention of oxygen-induced seizures during hyperbaric oxygen therapy.