Evoked potentials in trigeminal neuralgia associated with multiple sclerosis

Pain associated with multiple sclerosis: systematic review and proposed classification

Pain is common in patients with multiple sclerosis (MS), but estimates of its prevalence have varied widely. The literature describing pain in MS patients spans four decades and has employed a range of different methodologies. We undertook a systematic review in order to summarize current understanding of the association between MS and pain and provide a basis for the design and interpretation of future studies. The point prevalence of pain in patients with MS is nearly 50%, and approximately 75% of patients report having had pain within one month of assessment. Pain adversely affects most aspects of health-related quality of life, including functional domains such as the ability to work. The presence of pain in patients with MS is associated with increased age, duration of illness, depression, degree of functional impairment, and fatigue. Several different types of pain are found in patients with MS, including extremity pain, trigeminal neuralgia, Lhermitte's sign, painful tonic spasms, back pain, and headache. Putative mechanisms of pain in patients with MS are discussed, and a classification of pain in MS is proposed. Few randomized clinical trials of treatments for MS pain have been conducted, and the limitations of current knowledge regarding approaches for treating MS pain are discussed. Suggestions for future studies that would increase understanding of the natural history, mechanisms, and treatment of pain in patients with MS are presented.

Trigeminal neuralgia and other neuropathic pain syndromes of the head and face

Trigeminal neuralgia is the most common craniofacial pain syndrome of neuropathic origin. Although the diagnosis remains based exclusively on history and symptomatology, modern diagnostic techniques, particularly high-resolution magnetic resonance imaging, provides valuable new insight into the pathophysiology of these cases with additional implications for therapeutic strategies. Other neuropathic syndromes affect the trigeminal nerve and warrant different treatments with varied rates of success. Rarely, neuralgias of other cranial nerves mimic trigeminal neuralgia. Finally, it is imperative to distinguish atypical facial pains from these neuropathic syndromes to avoid unsuccessful therapies.

Brain-stem trigeminal and auditory evoked potentials in multiple sclerosis: physiological insights

Thirty-six patients with multiple sclerosis were evaluated by means of brain-stem trigeminal and auditory evoked potentials. The brain-stem auditory evoked potentials (BAEPs) were abnormal in 26 patients (72.2%). Brain-stem trigeminal evoked potentials (BTEPs) yielded similar results, showing distorted waveforms and/or prolonged latencies in 25 patients (69.4%). As expected, the MRI proved to be the most efficient single test, revealing plaques in 86.4% of the patients evaluated. However, the diagnostic accuracy of MRI was lower than that provided by the combination of the BTEP and BAEP (88.9%). Moreover, in patients having signs of brain-stem involvement, the BTEP, alone and in combination with the BAEP, proved to be more sensitive than the MRI in revealing brain-stem lesions. Correlation between clinical and BTEP findings could be found only in those patients who presented with signs of trigeminal involvement such as trigeminal neuralgia or dysesthesiae. The analysis of the BTEP waveforms showed two distinct types of abnormality-a peripheral type and a central type-suggesting plaques in distinct locations. Both the BTEP and the BAEP demonstrated a correlation with the clinical course of the disease and the condition of the patient at the time of the evaluation. Relapse of the disease was associated with a marked prolongation of the central conduction time in the BTEP and in the BAEP, suggesting the application of such studies to the monitoring of unstable patients in the evaluation of new therapeutic protocols.

Trigeminal neuropathic pain

Typical trigeminal neuralgia is characterized by episodic, unilateral, lancinating, triggerable, often shock-like facial pains, and pain-free intervals. Trigeminal neuropathic pain could be defined as constant unilateral facial pain of variable intensity, is non-triggerable, and unremitting. Atypical trigeminal neuralgia is an overlap syndrome with both episodic and constant pain. Patients with clear pathology of the trigeminal system often have sensory loss and atypical pains. The leading theory of causation of typical trigeminal neuralgia points to minimal compression and demyelination at the root entry zone (REZ) of the trigeminal nerve. In the experience of many neurosurgeons, atypical pains result from lesions or injuries of the trigeminal nerve root distal to the REZ. In a review of 122 patients, distal trigeminal pathology correlated with a clinical syndrome of trigeminal neuropathic pain. An hypothesis is presented that peripheral lesions of the trigeminal nerve behave as do other peripheral nerve lesions in that they are associated with sensory loss, deafferentiation and non "tic-like" pains. This may be due to the asynchronous spatial temporal dispersion of abnormal centrally-propagating axonal activity in nociceptive and non-nociceptive fibers from the region of pathology. This is opposed to the putative synchronous multifiber volleys which may emanate from the proximal trigeminal REZ in patients with typical trigeminal neuralgia. It appears that classical trigeminal neuralgia may be an exception to the rule that nerve injuries typically produce symptoms like constant pain and allodynia. Trigeminal neuropathic pain is, in some ways, a more general syndrome in that it is a painful nerve injury of the distal trigeminal nerve.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence and clinical features of trigeminal neuralgia, Rochester, Minnesota, 1945-1984

The overall crude incidence rate of trigeminal neuralgia per 100,000 population in Rochester, Minnesota, for 1945 through 1984 was 4.3 for both sexes combined. The age-adjusted (to total 1980 US population) rate for women (5.9) was significantly higher than that for men (3.4). Annual incidence rates increased significantly with age in both women and men. Data based on evidence in the medical records suggest that trigeminal neuralgia is a rather rare and unpredictable disease: The number of episodes varies from 1 to 11, and length of episode from 1 day to 4 years. This study indicates an elevated relative risk associated with hypertension (both overall and among women in the cohort). Also, prevalence of multiple sclerosis was significantly greater among the group of 75 patients who had trigeminal neuralgia. Since the data on treatment in this study do not correspond to a randomized clinical trial, they are presented as empirical results only and show no single treatment of choice for trigeminal neuralgia.

Serial recordings of multimodality evoked potentials in multiple sclerosis: a four year follow-up study

Pattern reversal visual, brain-stem auditory, and short latency median nerve somatosensory evoked potentials (EPs) were evaluated in a prospective study over 4 years in 20 patients with clinically definite sclerosis (MS). Standardized neurological examinations were done at regular intervals and correlated with EP findings. The highest incidence of EP abnormalities occurred in the visual system followed by the somatosensory and auditory systems. Clinical relapse was usually accompanied by EP deterioration, but clinical improvement often occurred without parallel EP recovery. EP changes were not always related to clinical symptoms and often took place during remission periods in the absence of clinical changes. There was no significant correlation between clinical and electrophysiological progression within any given sensory modality. The progression of clinical disability, however, showed a fairly good correlation with the overall progression of EP abnormalities. We conclude that EPs complement the neurological exam in the evaluation of MS and may have a place in the investigation of the effects of therapeutic agents on the neurological status in MS.