Gabapentin for spasticity and autonomic dysreflexia after severe spinal cord injury.

STUDY DESIGN: Using a complete transection spinal cord injury (SCI) model at the fourth thoracic vertebral level in adult rats, we evaluated whether blocking noxious stimuli below the injury diminishes abnormal somatic and autonomic motor reflexes, manifested in muscular spasticity and hypertensive autonomic dysreflexia, respectively. Gabapentin (GBP) is well tolerated and currently used to manage neuropathic pain in the SCI population; evidence suggests that it acts to decrease presynaptic glutamate release. As clinical evidence indicates that GBP may suppress muscular spasticity in the chronic SCI population, we hypothesized that preventing neurotransmission of noxious stimuli with GBP eliminates a critical physiological link to these distinct, debilitating SCI-induced secondary impairments. OBJECTIVES: Behavioural assessments of tail muscle spasticity and mean arterial blood pressure responses to noxious somatic and/or visceral stimulation were used to test the effects of GBP on these abnormal reflexes. SETTING: Lexington, Kentucky. METHODS: We used femoral artery catheterization and radio-telemetric approaches to monitor blood pressure alterations in response to noxious colorectal distension (CRD) weeks after complete SCI. RESULTS: At 2-3 weeks post-SCI, acute GBP administration (50 mg kg(-1), i.p.) significantly attenuated both autonomic dysreflexia and tail spasticity induced by noxious stimuli compared with saline-treated cohorts. CONCLUSION: These results show, for the first time, that a single-pharmacological intervention, GBP, can effectively attenuate the manifestation of both muscular spasticity and autonomic dysreflexia in response to noxious stimuli.

Acetyl-L-carnitine treatment following spinal cord injury improves mitochondrial function correlated with remarkable tissue sparing and functional recovery.

We have recently documented that treatment with the alternative biofuel, acetyl-L-carnitine (ALC, 300 mg/kg), as late as 1 h after T10 contusion spinal cord injury (SCI), significantly maintained mitochondrial function 24 h after injury. Here we report that after more severe contusion SCI centered on the L1/L2 segments that are postulated to contain lamina X neurons critical for locomotion (the "central pattern generator"), ALC treatment resulted in significant improvements in acute mitochondrial bioenergetics and long-term hind limb function. Although control-injured rats were only able to achieve slight movements of hind limb joints, ALC-treated animals produced consistent weight-supported plantar steps 1 month after injury. Such landmark behavioral improvements were significantly correlated with increased tissue sparing of both gray and white matter proximal to the injury, as well as preservation of choline acetyltransferase (ChAT)-positive neurons in lamina X rostral to the injury site. These findings signify that functional improvements with ALC treatment are mediated, in part, by preserved locomotor circuitry rostral to upper lumbar contusion SCI. Based on beneficial effects of ALC on mitochondrial bioenergetics after injury, our collective evidence demonstrate that preventing mitochondrial dysfunction acutely "promotes" neuroprotection that may be associated with the milestone recovery of plantar, weight-supported stepping.