Neuropathic pain usually manifests as burning or shooting pain. So-called plus symptoms such as hyperalgesia and allodynia, but also minus symptoms such as hypoaesthesia and hypalgesia may indicate neuropathic damage. Even a simple basic clinical and neurological examination can provide the first clue. Also helpful are specific questionnaires that can be used to query the typical symptoms.
A gold standard in further diagnostics has not yet been determined. In general, the assumption is substantiated by neurophysiological tests. The measurement of the nerve conduction velocity does not detect damage to the thin nerve fibers, nor can centrally-diagnosed neuropathic pain be detected. In recent years, Quantitative Sensory Testing (QST) has established itself as a very helpful but also elaborate study. Sensory-sensitive evoked, and laser-evoked potentials and skin biopsies are also recommended. If neuropathic pain is suspected, a neurologist should be consulted.
The most important and first step is to clarify and treat reversible causes. Doctors and patients must be aware that pure pain therapy for neuropathic pain can be only partially successful. For example, the National Neuropathy Guide for Adolescent Diabetes and other guidelines on neuropathic pain describe a 30-50% palliative benefit, an improvement in sleep and quality of life, and participation in social life and work ability as realistic therapeutic goals.
There are a number of drug-related options: tricyclic antidepressants, in particular, amitriptyline, are the first recommendation in the guidelines. However, it is not suitable for geriatric patients for a variety of reasons. In addition to strong anticholinergic side effects that can trigger and exacerbate cognitive impairment, interactions, QT prolongation, dizziness, and increased fall are good arguments against using tricyclics in the elderly.
Other first-choice recommendations include the calcium channel ligands gabapentin and pregabalin. Pregabalin is also approved for central neuropathic pain. But even here, the side effects are sometimes considerable and can prevent the use of these drugs. Dizziness and sleepiness should be mentioned here. Both drugs are eliminated renally and must be adjusted in renal insufficiency in the dose.
Duloxetine is another medicine approved and effective for painful diabetic neuropathy. The serotonin-norepinephrine reuptake inhibitor (SNRI) is relatively well tolerated but has some interactions that need attention. As the desired side effect, the second indication of duloxetine is remarkable: stress incontinence. Selective serotonin reuptake inhibitors (SSRIs) are not effective in neuropathic pain. The well-known carbamazepine is only the first choice for trigeminal neuralgia. However, the interactions and side effects make the use of the multimorbid patient problematic.
Peripheral analgesics have not shown efficacy in neuropathic pain in studies. However, opioids have a place in their therapy, especially tramadol and oxycodone. As a newer substance tapentadol has been developed with the two targets for opioid receptors and norepinephrine reuptake inhibition specifically for neuropathic pain. In the treatment of painful diabetic neuropathy, it shows good results in the studies so far. Due to a lack of interaction potential, it is an interesting drug for geriatric patients.