Pain and Spasticity
Pain is an important consequence of spinal cord injury (SCI) in that two thirds of patients with SCI report pain, and in one third of those the pain is severe. Clearly, this is a rich area for future research. Insights have been gained from animal models of SCI, which suggest a number of potential therapeutic approaches. For example, preemptive strategies, which limit secondary injury in the hours, days, or weeks after acute SCI, might also prevent the development of below-level neuropathic pain. Perhaps the largest impediment to clinical research has been the lack of a coherent strategy to both categorize SCI pain and to accurately communicate the nature of the SCI pain. The new IASP classification scheme should substantially solve this problem.
Treating SCI pain can be a frustrating experience, both for the patient and the physician. Neither current pharmacologic therapy nor surgery is predictably successful for severe below-level SCI. The promise of innovative agents, such as intrathecal gabapentin, or a new class of analgesics, the conotoxins, is considerable. Dorsal root entry zone lesions in patients with “end-zone” pains can be remarkably successful. Whether physiologic guidance of dorsal root entry zone surgery will improve outcome remains to be proven. With increasing recognition that patients with SCI present to clinicians with a host of pains, and not one discrete syndrome, more specific clinical trials may emerge, and our treatment of these patients will become increasingly evidence based.
In contrast to SCI pain, oral pharmacologic therapy of spasticity is effective in most patients. Only when a patient has failed trials of baclofen and tizanidine or has subsequently become refractory to these agents can we say that the patient’s spasticity is truly medically intractable. Interventional methods such as botulinum toxin A injections may play an intermediate role in the management of these more pernicious cases. Although major ablative procedures dominated the therapy of intractable spasticity in the past, the advent of more effective oral agents combined with the proven efficacy and safety of intrathecal baclofen has all but eliminated these procedures for the litany of spasticity treatments. Despite these advances, less invasive ablative procedures, such as percutaneous thermal rhizotomy, can still be useful in paraplegics who would welcome flaccidity as an alternative to their spasticity and who are not functionally dependent on some degree of spasticity.
Neurogenic Bladder and Sexual Function
The last several decades have led to an improved understanding of the physiologic alterations in bladder and sexual function after SCI. This in turn has led to better clinical management. With the proper surveillance and follow-up, many secondary complications can be prevented and quality of life can be significantly improved.
In general, bladder dysfunction after SCI falls into two categories: upper motor neuron syndrome and lower motor neuron syndrome. The type of bladder dysfunction present dictates the appropriate management strategies. Lower motor neuron dysfunction is characterized by bladder flaccidity requiring passive drainage. Upper motor neuron is considerably more complex and can be accompanied by 1) detrusor hyperreflexia with urge incontinence or 2) detrusor–sphincter dyssynergia. The latter is characterized by impaired coordination between the detrusor and outlet-associated structures leading to chronically elevated bladder pressures. In the presence of detrusor–sphincter dyssynergia, ongoing urological surveillance is required to prevent silent deterioration and possible renal failure. Management of upper motor neuron dysfunction is evolving, and the role of relatively new interventions, such as botulinum toxin A, capsaicin, or capsaicin analogues, and functional electrical stimulation, is still being defined.
Similar to neurogenic bladder management, significant strides have been made in the management of sexual dysfunction after SCI. With our current treatment options it is realistic to expect the vast majority of SCI patients to be able to participate in sexual activities if they so desire. Sildenafil has rapidly emerged as the treatment of choice. Furthermore, using techniques such as vibratory stimulation and electroejaculation, men with SCI can successfully father children. SCI does not impact fertility in women.