RESUMEN
BACKGROUND: The promising utility of multi-modality evoked potential batteries to objectively measure multi-tract dysfunction has been evaluated by several groups using different methods. OBJECTIVE: To independently evaluate the use of multi-modality evoked potential batteries as surrogate biomarkers for both physical and cognitive status in a cohort of Primary Progressive Multiple Sclerosis patients and identify the most potentially useful scoring method of those described. METHODS: 28 Patients with Primary Progressive Multiple Sclerosis underwent clinical evaluation with Kurtzke's Modified EDSS and the Multiple Sclerosis Functional Composite (MSFC). 19 Participants also underwent the Minimal Assessment of Cognitive Function in Multiple Sclerosis. Visual, Brainstem Auditory, Somatosensory and Motor Evoked Potentials were recorded on all. Results were graded by variants of the Global Evoked Potential Score, Multiple Evoked Potential Score and Summation of Z transformed Evoked Potential Latencies for correlation against the clinical scores. CONCLUSIONS: Multi-modal evoked potential batteries generally show moderate and useful correlation with clinical status as measured by the regulatory standard of EDSS (r = .65 vs. mEPS p < .005) and MSFC (r = .39 vs. mEPS p < .05). The graded qualitative mEPS scoring system displayed the strongest relationship although the influence of scoring system applied appeared reassuringly minimal. Non-association with cognitive impairment is an important limitation however.
Asunto(s)
Electrodiagnóstico/métodos , Potenciales Evocados , Esclerosis Múltiple Crónica Progresiva/diagnóstico , Esclerosis Múltiple Crónica Progresiva/fisiopatología , Examen Neurológico/métodos , Adulto , Anciano , Estudios de Cohortes , Evaluación de la Discapacidad , Femenino , Humanos , Masculino , Persona de Mediana Edad , Esclerosis Múltiple Crónica Progresiva/psicologíaRESUMEN
Nerve conduction studies (NCS) and electromyography (EMG), often shortened to 'EMGs', are a useful adjunct to clinical examination of the peripheral nervous system and striated skeletal muscle. NCS provide an efficient and rapid method of quantifying nerve conduction velocity (CV) and the amplitude of both sensory nerve action potentials (SNAPs) and compound motor action potentials (cMAPs). The CV reflects speed of propagation of action potentials, by saltatory conduction, along large myelinated axons in a peripheral nerve. The amplitude of SNAPs is in part determined by the number of axons in a sensory nerve, whilst amplitude of cMAPs reflects integrated function of the motor axons, neuromuscular junction and striated muscle. Repetitive nerve stimulation (RNS) can identify defects of neuromuscular junction (NMJ) transmission, pre- or post-synaptic. Needle EMG examination can detect myopathic changes in muscle and signs of denervation. Combinations of these procedures can establish if motor and/or sensory nerve cell bodies or peripheral nerves are damaged (e.g. motor neuronopathy, sensory ganglionopathy or neuropathy), and also indicate if the primary target is the axon or the myelin sheath (i.e. axonal or demyelinating neuropathies). The distribution of nerve damage can be determined as either generalised, multifocal (mononeuropathy multiplex) or focal. The latter often due to compression at the common entrapment sites (such as the carpal tunnel, Guyon's canal, cubital tunnel, radial groove, fibular head and tarsal tunnel, to name but a few of the reported hundred or so 'entrapment neuropathies').