The palmomental reflex predicts earlier corticobulbar involvement in ALS

The palmomental reflex in amyotrophic lateral sclerosis - a clinical sign of executive or motor dysfunction?

Objective: The palmomental reflex (PMR) is commonly interpreted as a frontal release sign, but it has also been discussed as a clinical marker of motoneuron affection in amyotrophic lateral sclerosis (ALS). The aim of this study was to investigate the impact of motor dysfunction versus neurocognitive impairment on the appearance of PMR in amyotrophic lateral sclerosis (ALS). Methods: 97 patients with ALS and ALS-variants were enrolled in this prospective, cross-sectional study. PMR was examined in a standardized procedure and the neurocognitive profile was assessed using the Edinburgh Cognitive and Behavioral ALS Screen (ECAS). Disease severity and motor function were recorded using ALS Functional Rating Scale revised (ALSFRS-R) and standardized clinical assessment. Results: 52% of all patients had a positive PMR (PMR+). These patients showed more frequently signs of motor dysfunction in the bulbar region (p < 0.001), impaired cognitive performance in the ECAS ALS-specific score (p < 0.05), predominantly in executive functions (p < 0.01), as well as lower scores in ALSFRS-R (p < 0.05) compared to patients without PMR (PMR-). A multivariate logistic regression analysis revealed that bulbar involvement, executive function impairment, and a lower motor and respiratory (non-bulbar) ALSFRS-R significantly predicted PMR+ (all p < 0.05), with bulbar involvement being a stronger predictor than executive function impairment. Discussion: In this study, we showed that bulbar involvement is a much stronger predictor on the appearance of PMR compared to executive function impairment. PMR is therefore primarily a sign for bulbar involvement, rather than a sign for executive dysfunction in ALS patients.

MRI cortical feature of bulbar impairment in patients with amyotrophic lateral sclerosis

The decline of voluntary bulbar functions such as speech and swallowing are among the clinical manifestations of amyotrophic lateral sclerosis (ALS) influencing a worst prognosis. Differential diagnosis between the contribution of upper motor neuron (UMN) and lower motor neuron degeneration to the bulbar impairment is often hard. Thinning and T2* hypointensity of the primary motor cortex have been recently suggested as possible MRI markers of UMN impairment in ALS patients, but little research has purposely targeted the orofacial region of the primary motor cortex (fM1). With the aim of finding an MRI marker of UMN impairment responsible for bulbar dysfunction, we investigated the T2* signal intensity of fM1 and the relationship with bulbar impairment in ALS patients. Fifty-five ALS patients were examined with 3 T MRI. Their fM1 was evaluated both qualitatively in terms of T2* signal intensity and quantitatively by measuring its magnetic susceptibility with Quantitative Susceptibility Mapping (QSM). Bulbar functions were assessed clinically, by neurological examination and using the items 1–3 of the ALSFRS-R, and with neurophysiological tests.

The marked hypointensity of fM1 was detected in 25% of ALS patients, including all patients with bulbar onset, and was 74% sensitive, 100% specific and 91% accurate in diagnosing functional bulbar impairment. Such hypointensity involved the middle and ventral part of fM1 and was usually visible in both hemispheres. The magnetic susceptibility was significantly higher in patients with marked fM1 hypointensity than in the other patients (p ≤ .001).

The relationship with clinical and neurophysiological data suggests that such feature could be a marker of UMN degeneration for voluntary bulbar functions.

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T2* hypointensity was assessed in the orofacial region of M1 (fM1) of ALS patients.

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All ALS patients with marked T2* hypointensity of fM1 had bulbar impairment (BI).

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The marked T2* hypointensity of fM1 was 91% accurate in diagnosing BI.

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fM1 hypointensity can be a marker of upper motor neuron degeneration causing BI.