Paolo Bongioanni

*Neurological Rehabilitation Unit - Neuroscience Department, University of Pisa/NeuroCare onlus Italy* 

### **1. Introduction**

664 Amyotrophic Lateral Sclerosis

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**Amyotrophic lateral sclerosis** (**ALS**), also called *Lou Gehrig's disease*, is a rapidly progressive neuromuscular disease that attacks the neurons responsible for controlling voluntary muscles. It belongs to a group of disorders known as *Motor neuron diseases* (*MND*): all these syndromes share a common molecular and cellular pathology comprising degeneration of motor neurons (MNs) in cortex, brainstem and/or spinal cord, and the presence of characteristic ubiquitin and TDP-43-immunoreactive intraneuronal inclusions.

ALS prevalence in Western countries ranges from 2.7 to 7.4 per 100,000 (Worms, 2001). In 90 to 95 percent of all patients with ALS (PALS), the disease occurs sporadically (*sporadic ALS*, *sALS*); in 5 to 10 percent there is a family history of ALS (*familial ALS*, *fALS*). Most people developing ALS are between the ages of 40 and 70 years (Haverkamp et al., 1995). The disease is 20% more common in men than in women, although more recent data suggest that the gender ratio may be approaching equality (Logroscino et al., 2008).

The cause of ALS is not known, and it is not clear why ALS strikes some people and not others, but both genetic (Ticozzi et al., 2011) and environmental factors (Callaghan et al., 2011; Calvo et al., 2010; Ferrante et al., 1997) may play a role.

In PALS, both the brain upper MNs (UMNs) and the brainstem or spinal cord lower MNs (LMNs) degenerate or die: unable to function, the muscles gradually weaken, waste away, and twitch, leading to a wide range of disabilities. Patients lose their strength and the ability to move their body, but usually maintain control of eye muscles.

Approximately 70% of PALS have a *spinal form* of the disease: they present with symptoms which may start either distally or proximally in the upper or lower limbs. Some patients see the effects of the disease on a hand or arm, as they experience difficulty with simple tasks requiring manual dexterity, such as buttoning a shirt, writing, or turning a key in a lock; in other cases, symptoms initially affect one of the legs, and patients experience awkwardness when walking or running, or they notice that they are tripping or stumbling more often.

Patients with *bulbar-onset* ALS usually present with dysarthria leading to slow slurred speech or a nasal quality; they may also develop dysphagia for solid or liquids after noticing speech problems; almost all patients with bulbar symptoms complain of sialorrhoea with excessive drooling due to difficulty of swallowing saliva and UMN-type facial weakness, which affects the lower part of the face, causing difficulty with lip seal and blowing cheeks.

Communication Impairment in ALS Patients Assessment and Treatment 667

limited, support such an interpretation. An early study on articulatory kinematics in two PALS showed slowed articulatory movements, reduced displacement of the tongue and lip, together with exaggerated displacements of the jaw during diadokokinetic tasks (Hirose et al., 1982). A more recent study of articulatory movements in a group of 9 PALS reported an impairment of articulatory speed during vowels (Yunusova et al., 2008): aberrant displacements were found to be word- and vowel-dependent and were more consistently present in movements of the tongue than in those of other articulators, and occasionally in the jaw; the jaw displacements were smaller than normal in words requiring larger articulator movements (e.g., consonant plus low vowel), but were larger than normal in words that only required relatively small jaw movements (e.g., consonant plus high vowel),

Whereas initially, along a gradual slowing of *speaking rate*, *speech intelligibility* remains relatively high, it decreases overtime, when dysarthria becomes more and more apparent to PALS themselves and their listeners. Yorkston and co-workers (1993) suggested that speech intelligibility may vary across dysarthric patients depending on the subsystems that are preserved (e.g., relatively less impaired respiratory-phonatory subsystem and the jaw might be associated with better speech intelligibility); the rate of disease progression; and the

Because a person's ability to communicate orally is typically assessed based on speech intelligibility, anticipating the decline in intelligibility in a sensitive way is critical for timely clinical management of bulbar PALS. In this regard, longitudinal studies are, indeed, necessary when the goal of research is to identify early predictors of future changes; additionally, longitudinal studies are advantageous when dealing with heterogeneous populations, as in the case of PALS, since each patient can serve as his own control. Investigations of such a type documented the decline in speech intelligibility and speaking rate (Kent et al., 1992; Mulligan et al, 1994; Nishio & Niimi, 2000; Yorkston et al., 1993); and some studies have also identified several acoustic-based speech markers of disease

In their retrospective study of more than a hundred clinical cases, Yorkston and co-workers (1993) reported that speaking rate was a reliable predictor of speech intelligibility decline, by observing a rapid deterioration in speech intelligibility shortly after a decline in speaking rate to 100-120 words per minute. Such a finding was replicated by Ball and co-workers (2002) in a large group of patients with bulbar symptoms of different severity: the authors suggested that speaking rate decline to 100-120 words per minute should serve as a clinical

Moreover, since ALS progresses so rapidly in many subjects, an important goal of clinical management is to anticipate functional changes in patients' performance in order to teach new communication strategies and compensatory skills before the patient's ability to learn these skills is impacted by the severity of their condition. Recently, Yunusova and coworkers (2010) in a longitudinal study on 3 PALS tested the feasibility of using kinematic measures as early predictors of intelligibility decline, trying to understand the relationship between physiologic changes in speech movements and clinical measures of speech performance (such as speaking rate and speech intelligibility). Lip and jaw movements were

Results showed that, differently from oral strength measures, changes in lip and jaw movements were related to ALS progression: in two out of 3 PALS, the changes in measures

indicator for beginning to support communication by assistive technology.

suggesting difficulty in scaling of the vowel-related movements.

progression (Mulligan et al., 1994; Ramig et al., 1990).

quantified with respect to their size, speed, and duration.

patient's cognitive status.

The gag reflex is preserved and often brisk, whereas the soft palate may be weak; patients show wasting and fasciculations of the tongue which moves slowly, also due to muscle hypertonia. The other cranial nerves remain intact, although in late stages of the disease patients may very rarely develop a supranuclear gaze palsy or oculomotor palsy (Kobayashi et al., 1999; Okuda et al., 1992).
