Objective: To determine which of the three motor functions (bulbar, upper extremities, lower extremities) was normally preserved at the time that respiratory symptoms occurred in amyotrophic lateral sclerosis (ALS).
Background: Respiratory failure is the major cause of death in ALS. The course of the disease progression to the onset of subjective respiratory symptom can vary from patient to patient and the diversity of this progression in ALS patients is not well understood.
Patients/methods: The subjects were 120 Japanese patients with sporadic ALS who were followed-up at our hospital or for whom precise information was available regarding death or the time that the patient required tracheotomy or ventilation assistance. Symptoms started: in the upper limbs in 47 patients; in the lower limbs in 44 patients; in the bulbar region in 22 patients; as the combined type (two regions involved simultaneously on initial presentation) in 6 patients; and with respiratory symptoms in 1 patient.
Results: At the time of the appearance of respiratory symptoms, 43 patients (35.8%) had some normally preserved motor function. Significantly fewer patients with progressive bulbar palsy maintained one or more normal motor functions (14%) compared to patients whose disease started in the extremities (43%). Patients were divided into two groups depending on whether they had significant bulbar involvement at the time of the appearance of respiratory symptoms: 88 patients had significant bulbar involvement (B type), and 32 patients did not (R type). Based on the Kaplan-Meier survival curves, no significant difference in the median survival time was noted between the two groups (R type, 29.4 months vs. B type, 32.5 months; p = 0.06). We could not find any difference about clinical characteristics such as gender, onset age, initial site between R and B group. The motor functions that were preserved at the time of respiratory symptom onset included: bulbar function in 32 patients (26.7%); lower extremity function in 12 patients (10%); and upper extremity function in only 3 patients (2.5%). The use of mechanical ventilation in ALS patients with one or more preserved motor functions was significantly higher than in those without any normally preserved motor function (p = 0.03).
Conclusions: From a low rate of upper extremity motor function preservation, respiratory function deterioration appears to be related to upper-limb involvement, likely due to a possible link to diaphragmatic function. Advanced directives should carefully address the use of mechanical ventilation in patients without bulbar symptoms.