Ropivacaine and dexamethasone: a potentially dangerous combination for therapeutic pain injections.

INTRODUCTION: Targeted spinal steroid injections are effective in reducing back pain in selected patient populations and carry a small risk of significant adverse neurological outcomes. Recent recommendations are for the use of non-particulate steroid agents for all spinal injections to reduce the risk of neurovascular embolic adverse events. Many injections have used a combination of local anaesthetic agent with the steroid. At our institutions, we have recently observed interactions between ropivacaine and dexamethasone combinations ascribed to the incompatibility of the former with alkaline solutions, resulting in rapid crystallisation. This study has further investigated the combinations of commonly used local anaesthetic and steroid combinations to determine if such precipitation effects are more widespread. METHODS: The commonly used local anaesthetics (lignocaine, bupivacaine, ropivacaine) and the non-particulate steroid dexamethasone sodium phosphate combinations were evaluated macroscopically, microscopically, and pH values measured. Where crystallisation was observed the rate of precipitation and crystal size was measured. Contamination of ropivacaine with sodium bicarbonate solution was also evaluated. Particulate size of the particulate steroid agent betamethasone acetate was evaluated as a comparison. RESULTS: All mixtures of ropivacaine and the non-particulate dexamethasone sodium phosphate assessed demonstrated a pH-dependent crystallisation of the solution. No precipitation was demonstrated with the combinations of dexamethasone and lignocaine or bupivacaine. Contamination of ropivacaine with residual sodium bicarbonate in a drawing up needle following air clearing had a precipitation effect. CONCLUSION: We describe the effect of crystallisation with the combination of ropivacaine and the non-particulate steroid, dexamethasone sodium phosphate, a mixture that has been used in the literature for targeted pain injections. As this may be considered a non-particulate steroid/anaesthetic injectate, this would potentially carry increased risk if inadvertent intravascular injection occurred during a targeted spinal injection, as has been described with particulate steroid agents. This is due to the elevated pH of dexamethasone and the incompatibility of ropivacaine with alkaline solutions.

Trigeminal neuralgia secondary to giant Virchow-Robin spaces: a case report with neuroimaging.

Virchow-Robin spaces are pial-lined, interstitial, fluid-filled structures that accompany penetrating arteries and arterioles as they enter the cerebral substance. Occasionally they may enlarge and become giant Virchow-Robin spaces (GVRS) and produce mass effect. Various neurological symptoms have been described in association with GVRS, however, trigeminal neuralgia has not yet been reported in this context. We present a case of trigeminal neuralgia secondary to dorsal pontine giant Virchow-Robin spaces (GVRS) and highlight the diagnostic radiologic features. Routine 1.5 T MRI sequences were sufficient to diagnose the GVRS and a diffusion tensor imaging (DTI) study revealed distortion of the intrinsic trigeminal pathway. This study highlights the utility of routine MRI to study the intrinsic anatomy of the trigeminal pathway in pathological conditions.

Carboplatin and etoposide combined with bevacizumab for the treatment of recurrent glioblastoma multiforme.

Relapsed glioblastoma multiforme (GBM) responds poorly to standard therapies. Vascular endothelial growth factor (VEGF) is implicated in the development of GBM and the anti-VEGF monoclonal antibody bevacizumab has shown early clinical promise against malignant glioma. We treated six patients with recurrent GBM using bevacizumab combined with carboplatin and etoposide chemotherapy (ACE regimen). Toxicity was that expected for carboplatin and etoposide alone, except for an ischemic stroke in one patient. We observed partial responses in five patients and one responding patient developed extensive tumour necrosis after 2 cycles of treatment. Median progression-free and overall survival was 19 and 29.9weeks, respectively. Four responding patients developed recurrence, which was characterized by markedly less peri-tumoral edema, mass effect and necrosis compared with tumours at baseline. Two patients developed local extracranial extension. In conclusion, ACE was active in recurrent GBM and was mostly well tolerated.