Evoked potential studies in the antiphospholipid syndrome: differential diagnosis from multiple sclerosis.

BACKGROUND: The CNS manifestations of the antiphospholipid syndrome (APS) can mimic multiple sclerosis both clinically and radiologically. OBJECTIVE: To compare evoked potential studies in APS patients and patients with multiple sclerosis with similar neurological disability. METHODS: 30 APS patients with CNS manifestations and 33 patients with definite multiple sclerosis and similar neurological disability underwent studies of visual evoked potentials (VEP), somatosensory evoked potentials (SSEP) in the upper and lower limbs (UL, LL), and sympathetic skin responses (SSR) in the upper and lower limbs. RESULTS: The neurological manifestations in the APS patients included stroke (n = 17), transient ischaemic attacks (n = 10), and severe headache with multiple white matter lesions on brain MRI (n = 3). Abnormal SSEP (LL), and SSR (UL; LL) were seen in APS patients (37%, 27%, and 30%, respectively) but VEP and UL SSEP were rarely abnormal (10% and 6%, respectively in APS v 58% and 33% in multiple sclerosis; p = 0.0005, p = 0.008). Mean VEP latencies were more prolonged in multiple sclerosis (116 ms v 101 ms, p<0.001). Only one APS patient had abnormal findings in all three evoked potential studies, compared with seven patients in the multiple sclerosis group (p = 0.04) CONCLUSIONS: Abnormal VEPs are uncommon in APS in contrast to multiple sclerosis. Coexisting abnormalities in all other evoked potentials were similarly rare in APS. In patients with brain MRI findings compatible either with multiple sclerosis or APS, normal evoked potential tests, and especially a normal VEP, may support the diagnosis of APS.

R-R interval variation in Parkinson's disease and multiple system atrophy.

OBJECTIVE: To investigate whether the cardiac R-R interval variation (RRIV) is of value in differentiating patients with Parkinson's disease (PD) from multiple system atrophy (MSA). BACKGROUND: RRIV assessment is a simple procedure, reflecting mainly vagal efferent activity. Reduced RRIV was reported in MSA. METHODS: RRIV at rest and after 120 s of deep breathing was assessed blindly to clinical diagnosis in 22 PD and 20 MSA patients. The results were compared with data from 23 age-matched healthy subjects. RESULTS: RRIV at rest was 7.1 +/- 2.7% in PD and 9.7 +/- 7.2% in MSA, increasing after deep breathing to 11.2 +/- 6.3 and 12.3 +/- 6.6% correspondingly. The frequency of the RRIV abnormalities in the PD group (4/22, 18.2%) and MSA (6/20, 30%) were higher than among controls (P < 0.004). CONCLUSIONS: RRIV, either at rest or after deep breathing, may be abnormal both in PD and MSA, but does not distinguish between these disorders.

Electrophysiologic evaluation of upper motor neuron involvement in amyotrophic lateral sclerosis.

BACKGROUND: The demonstration of upper motor neuron (UMN) dysfunction in patients with amyotrophic lateral sclerosis (ALS) with predominantly lower motor neuron (LMN) signs is clinically sometimes difficult. METHODS: We analyzed the possible role of F and H waves in the diagnosis of UMN dysfunction in 36 patients with different clinical forms of ALS and 20 controls. In both lower limbs we evaluated F-wave persistence and the F/M ratio of tibial nerves, Hmax/Mmax ratio, vibratory and recurrent (paired) inhibition of the H-reflex. RESULTS: The persistence of the F-response was decreased significantly in the LMN group only. The F/M amplitude ratio, vibrated-H/rest-H amplitude ratio and conditioned H/rest H amplitude ratio were significantly increased in patients with predominantly UMN, as well as in those with predominantly LMN signs. H/M amplitude ratios did not differ between the various patient groups. CONCLUSION: These findings show that ALS patients, including those without clinical evidence of UMN involvement, have a marked disinhibition of anterior horn motor neurons. The simple tests described could support an UMN abnormality when clinical signs are lacking, and help to establish a diagnosis sooner and more accurately.

Anal sphincter EMG does not distinguish between multiple system atrophy and Parkinson's disease.

Clinical distinction of multiple system atrophy (MSA) from Parkinson's disease (PD) is often difficult. Several recent reports indicate that objective classification may be accomplished using electromyographic (EMG) testing of the anal or urethral sphincters, but some authors have found that these tests are not reliable for this purpose. We studied 13 patients with PD and 10 with probable MSA, as diagnosed by consensus of four movement disorders specialists, according to accepted clinical criteria. Anal sphincter EMG was performed blind to the clinical diagnosis. We found no significant differences in the mean duration of motor unit potentials (MUPs), mean MUP amplitude, or prevalence of polyphasic potentials, satellite potentials, very long duration MUPs, or spontaneous activity between the two groups. Thus, anal sphincter EMG does not differentiate between PD and MSA.

Hypertriglyceridemia may cause a subclinical peripheral neuropathy.

Recently few patients with a painful neuropathy, attributed to extremely high triglyceride levels, were reported. In a prospective study, we evaluated 16 patients with marked hypertriglyceridemia without other causes of neuropathy, using nerve conduction and autonomic function tests. Six subjects (37%) showed mild signs of an asymptomatic motor and/or sensory and/or autonomic axonal polyneuropathy. The study demonstrates, that hypertriglyceridemia may be associated with a mild axonal polyneuropathy, usually subclinical, in significantly more patients than previously considered.

Neurotoxicity of isolated limb perfusion with tumor necrosis factor.

Hyperthermic isolated limb perfusion (HILP) with tumor necrosis factor alpha (TNFalpha) is effective for advanced melanoma and sarcoma of the limbs. Ten patients undergoing HILP with TNFalpha were evaluated by neurological examinations, nerve conduction studies (NCS), sympathetic skin responses (SSR) and conventional and quantitative electromyography (EMG), performed before, 7 days and 6 weeks following HILP. Seven patients showed minimal clinical signs of peripheral nerve damage following HILP; in two the injury was evident electrophysiologically: 7 days following HILP five patients had paresthesias and/or hypoesthesia, one had a mild foot drop and one had autonomic disturbances in the affected limb. SSR was low in two patients in the affected limb, sensory nerve action potentials were not elicited in one, with normal motor NCS and EMG. At 6 weeks, four patients continued to have mild paresthesias and one had dysautonomia of the perfused limb. Sensory responses and SSR did not change, motor abnormalities were not found. These findings show that HILP with TNFalpha induces a mild, mainly sensory neuropathy in perfused limbs, not disturbing functionality and improving over time.

N30 somatosensory evoked potentials in patients with unilateral Parkinson's disease.

The N30 component of the somatosensory evoked responses (SEP) was reported as absent or abnormally low in various basal ganglia disorders, including Parkinson's disease (PD), but its relationship to the more affected side in asymmetric disease has not been assessed systematically. In 14 patients with unilateral PD and 10 controls, SEP were performed by stimulating each upper limb and recording from the parietal and frontal contralateral cortex. N30 was symmetric in 4 patients and 4 controls; it was asymmetric in 2 controls and in 8 patients (in 4 the responses were of lower amplitude over the affected hemisphere); no response was elicited in 2 patients and 4 controls. In all patients SEP were recorded off medication; in 9 of them the test was repeated following administration of L-dopa and did not show any significant changes. In conclusion, the N30 was asymmetric in a similar proportion of PD patients and controls. No correlation was found between the affected side and N30 latencies or amplitudes; no change was seen following L-dopa administration as well. The motor deficits and SEP abnormalities in PD probably reflect pathologies in different anatomical structures or functional circuits.