What s Primary Progressive Aphasia?

Slowly progressing aphasia was first described by Pick and Rosenfeld in the 18th century. Patients often present with language disorders of naming disorders, common in Alzheimer's disease (AD) and Pick's disease (PiD). In 1982, Mesulam reported 6 cases of patients with aphasia who were slowly progressing without intelligence and behavioral disorders. The concept of slow progressive aphasia was first proposed, which means progressive aphasia without dementia, which is more common in the early age and has a prolonged course. For many years, dementia can occur in advanced stages, and the lesions are mainly located around the left lateral hemisphere. Mesulam further enriched the concept of PPA in 1987 and described its clinical, neuroimaging, and pathological features. In 1990, Weintraub and other aptly named as primary progressive aphsia (PPA), and there have been scattered case reports since then. PPA is defined as the patient's progressive and limited language disorder, the course of which is prolonged for many years, and the absence of mass lesions, infarction or other brain lesions can explain its clinical manifestations. Language disorder is the only or prominent neurological abnormality in the course of disease. PPA is a rare disease whose neuropathology and etiology are unknown, and only a few cases have been reported. This type of patient presents with progressive language impairments, combined with visual misrecognition, spatial impairment or apraxia. A patient's language disorder can stand on its own for years and eventually manifest itself as dementia. This group of patients is a separate disease or an early manifestation of dementia, which is still controversial. To date, the data indicate that PPA and AD, PiD, PiD variants, non-specific cortical degeneration combined with spongiform degeneration, lack of clear distinctive histology (DLDH), and dementia of frontal lobe type (DFT) ), Frontal dementia with motor neuron disease and Creutzfeldt-Jacob disease (CJD).

Primary progressive aphasia

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Slowly progressing aphasia was first described by Pick and Rosenfeld in the 18th century. Patients often present with language disorders of naming disorders, common in Alzheimer's disease (AD) and Pick's disease (PiD). In 1982, Mesulam reported 6 cases of patients with aphasia who were slowly progressing, without intelligence and behavioral disorders, and first proposed the concept of slowly progressive aphasia, which means progressive without dementia.

PPA is usually onset by insidious attacks. It is more common in the early years of life, ranging from 48 to 73 years old, and the youngest case is 17 years old. More common in men. Mainly manifested as slow onset, gradually progressing language barriers, progress at different speeds. Aphasia gradually worsens after 5 to 11 years. Some patients can see mild right side signs such as facial paralysis, Babinski signs, or extrapyramidal signs. Patients' memory, reasoning, self-awareness, judgment ability, and behavior are relatively retained. Patient's body

Generally, after 2 to 6 years after the onset of symptoms, the language barrier gradually increases, and it can be seen that naming difficulties, inability to name, slow language throughput, difficulty in finding words, lack of grammar, speech and rhythm disorders, and lack of clarity. The language type is usually telegram, and the sentence length is shortened. Rarely: reduced language flexibility, repetitive language, cumbersome language, words and semantic errors, new words (new words), and stereotyped expressions. Nonverbal communication is not impaired, and is not impaired until the end of the disease. As the disease progresses, the barriers to understanding become more apparent. Writing was progressively impaired, with spelling errors, reversed word order, and inability to complete dictation. Narrative writing shows individual words or grammatically incomplete sentences. Read often words are omitted, replaced or added.

Non-fluent aphasia patients can see difficulty in naming, slow throughput, lack of grammar, grammatical comprehension and expression are significantly impaired, phonemic judgment is impaired, repetition is poor, counting range is limited, but memory is relatively reserved. Patients have comprehension capabilities, such as gestures, writing, and circuitous statements. Alternative facilities such as communication cards and notebooks are often used. Patients have the ability to acquire new skills and hobbies, and sometimes perform simple, instructional actions even when language function continues to deteriorate. Can often take care of themselves. Fluent aphasia patients have difficulty understanding empty words, redundant words, and single words.

Rosenfeld's first PPA autopsy found no diffuseness

1. Cerebrospinal fluid and serology are normal.

2. EEG: non-specific slow waves are often normal or visible, and focal slow waves of the left frontotemporal lobe are occasionally visible.

3. CT and MRI: early often without abnormalities. Extensive in late stages

The diagnosis of PPA is mainly clinical and excludes other diseases. Patients with language disorders often appear insidiously, gradually progressing, the course of the disease lasts longer, and there is generally no cognitive impairment in the early stages of the disease. In the end there was total aphasia, inactive silence and dementia. Most patients with fluent aphasia are diagnosed as AD, while patients with non-fluent aphasia are diagnosed as PiD, PiD variant, and DLDH. Kempler et al proposed the diagnostic criteria for PPA: (1) a group of syndromes with different clinical manifestations, mainly language disorders; (2) end-stage dementia does not necessarily appear; (3) cases with different speeds of progression; (4) head CT The examination was normal; (5) PET examination showed that the left temporal lobe brain metabolism was reduced. PPA with extrapyramidal signs can be seen in frontotemporal atrophy, but motor neuron disease is more common. Weintraub et al. Believe that non-fluent aphasia (Broca aphasia or percutaneous motor aphasia) is rare in AD and common in PPA, and has differential diagnostic value. The ability of PPA patients to acquire new knowledge and skills is different from that of AD patients, who often have persistently reduced motivation.

Mesulam (1992) proposed diagnostic criteria:

(1) Insidious onset, spontaneous oral expression or neuropsychological examination showing progressive progress in difficulty in finding words, inability to name, and impairment in language understanding.

(2) Two years after the onset of the disease, the daily living ability is impaired due to language barriers.

(3) The language function is normal before the onset of the disease (except for dyslexia).

(4) No obvious apathy, insufficiency, near memory loss, impaired visual space, visual loss, sensation, and dyskinesia within 2 years of onset Confirmed).

(5) There may be miscalculations and dyskinesias in the early stages.

(6) Other neurological deficits may occur 2 years after the onset, but speech impairment is most prominent from beginning to end. Progress is fastest.

(7) Excluding stroke, tumor and other diseases.

Gender differences in hemisphere lateralization have been found. Compared with men, women's left hemisphere language function and right hemisphere visual space function are weak. Brain activity during language is limited to the left subfrontal gyrus for men, and for the bilateral subfrontal gyrus for women. Studies by Shaywitz et al. Found that the differences between men and women's language exist in the level of speech processing. Harasty et al. Found that compared with men, women have relatively larger volumes in the temporal lobe (the central part of the Wernicke language area) and the subfrontal gyrus (the Broca language area in the dominant hemisphere). It is generally believed that the serial language function focuses on the dominant left hemisphere, which mainly refers to speech and syntax; the non-dominant hemisphere focuses on overall and practical functions, so it is not difficult to understand why men with PPA are more common.

Mesulam et al. Considered that PPA is a group of clinical syndromes that are not related to AD histopathology based on the prevalence of under 65, the type of aphasia, and the prevalence of men. It is now believed that PPA is a relatively selective degeneration of the left lateral lateral fissure, which is a non-AD type lobe atrophy that can be distinguished from AD. Some scholars believe that PPA is a group of syndromes due to dementia in its late stage of disease, and its pathological and clinical characteristics are significantly different from AD, most likely a variant of PiD. Some scholars believe that PPA is a variant of AD and can be manifested as a long-term language disorder followed by other neuropsychological disorders. Insidious attack, slowly progressing, long-term course. Speech disorders often manifest as named aphasia. The area surrounding the left lateral fissure is mainly due to the involvement of the medial and inferior temporal gyrus, while the Wernicke area of the superior temporal gyrus is not involved, indicating that PPA is a degenerative disease rather than a vascular disease. AD is a common disease, and generally has nonverbal cognitive dysfunction within 12 months after symptoms appear. Early or early EEG shows extensive or focal abnormal slow waves; PPA patients do not have the above changes. PET examination of AD patients showed low metabolism in bilateral posterior parietal lobe, bilateral parietal lobe, and bilateral temporal parietal lobe. PET examination of DFT patients showed low metabolite in frontal lobe.

The non-fluent type of PPA is obvious because of the omission of fewer grammatical morphemes, which is obvious in throughput language and telegram language, which may be related to impairment of grammatical understanding. The fluent type of PPA, which is characterized by empty and redundant language, is related to difficulty in understanding the meaning of a single word. Functional neuroimaging studies have found that non-fluent PPA easily affects the frontal and anterior temporal regions of the left hemisphere.

Neuropathological studies have found that cytoplasmic immunostaining of phosphorylated microfilament epitopes indicates defects in phosphorylation, transport or disintegration of neural filaments, or damage to axons at the transport site, which may explain its pathogenesis.

In short, the etiology of PPA is unclear and needs further study.

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