It is about the global and progressive loss of the intellectual functions acquired previously, without disturbances of the vigilance.
It is necessary to know how to evoke the diagnosis in two circumstances:
– Memory disorders noticed by the patient, but more often by the entourage.
– Behavioral disorders.
The memory disorder is often the first sign, with a good persistence of retrograde memory but an impairment of learning. Several simple tests are used to evaluate the memory: despite his good will, the patient fails homogeneously.
All intellectual functions are affected, but to varying degrees, according to the course of the disease. Temporal disorientation is earlier than spatial disorientation. Logical reasoning is disrupted, with a loss of criticism of absurd stories and self-criticism. The mental calculation is preserved but the operations in several times are affected early.
Do not confuse a dementia syndrome:
– With a confusional syndrome, which is differentiated by disorders of vigilance, a slowdown
ideological; the installation is more acute, the evolution regressive.
– With language disorders : The preservation of intellectual functions that do not involve language allows the diagnosis.
– Some depressions of the elderly subject must always be mentioned, they are curable. The diagnosis is difficult and may be a test antidepressant treatment, or for some by seismotherapy.
A complete clinical examination must be performed:
The neurological examination of a degenerative dementia is classically normal, the presence of clinical signs must point to a curable cause.
We will look for the signs:
– vascular involvement: pyramidal semiology, frontal, presence of a Babinski sign, spasmodic laughter and cries, stroke sequelae, etc. ;
– involvement of the peripheral nervous system: polyneuritis;
– cerebellar syndrome or brainstem involvement.
The psychometric assessment is often necessary:
A simple test, the mini-mental-status (MMS) allows to appreciate the orientation, the learning, the attention, the language, the constructive activities. It is fast and standardized, even if imperfect.
The interrogation of the entourage is important.
The psychometric expertise is based on a battery of tests and specialized tests; the results are often inhomogeneous from one test to another, or even from one patient to another, but it may be indispensable for the diagnosis and allow evolution monitoring.
ADDITIONAL E XAMENS:
Diagnosis requires a review to confirm it and look for a curable etiology.
Look for kidney failure, hypercalcemia, dehydration, hypoglycemia, diabetes or dysthyroidism. Syphilitic serology is systematic. According to the signs of clinical calls: dosage of vitamin B12, immunological assessment, ceruloplasmin, cupremia.
The cranial scanner or MRI allows the diagnosis of frontal tumors, subdural hematomas, hydrocephalic, vascular dementia. The image found most frequently, however, is a generalized atrophy that is not very specific.
It is useful even if infectious or inflammatory causes are rare. In normal pressure hydrocephalus, fluid subtraction is a diagnostic test.
Dementias and degenerative pathologies:
It represents about 60% of the dementia of the elderly subjects.
The onset is insidious and progressive, marked mainly by memory disorders. The evolution is slow, and is formed in a few years a typical dementia syndrome.
The cholinergic system appears to be early modified and anticholinesterases have shown activity in the early forms.
Despite their rarity, they deserve a place because of their infectious cause: abnormal protein by its structure in space.Different forms are described.
Creutzfeldt Jakob disease (CJD): two forms are very well known: the sporadic form and the familial form, characterized by the installation of a dementia syndrome with myoclonus and a rapid evolution in a subject of more than 65 years.
More recently, the iatrogenic form has appeared after treatment with extractive growth hormone, but also after corneal and dura graft forms. These forms can reach young subjects; incubation time ranges from 16 months (intracerebral introduction) to 19 years (intramuscular growth hormone contamination).
Finally, the so-called variant form MCJ, the human form of bovine spongiform encephalopathy, due to the consumption of contaminated cattle products. The average age of onset of the disease is 25 years.
Initial psychiatric signs may make the diagnosis err. The clinic finds painful sensory symptoms, ataxia, myoclonus.Evolution is fast. The diagnostic certainty is obtained only by the cerebral biopsy. The frequency in France is minimal.
Very rare, the dementia table is associated with a frontal semiology in a subject of 50 to 60 years.
Autosomal recessive, it often begins with a neurological impairment (muscle rigidity, involuntary movements, mental disorders …). There is liver damage, tremor, a corneal green ring, a decrease in cupremia and ceruloplasmin, an increase in cupruria. Early treatment with chelators can be spectacularly effective.
Dementia is frequent and not influenced by treatment. In principle, it follows the long evolution of Parkinson’s disease.
CHORN OF HUNTINGTON:
Hereditary, autosomal dominant, it begins around 40 years and is easy diagnosis in front of the choreic movements and the family antecedents. A genetic test exists, the modalities of which are highly regulated.
Dementia and vascular pathology:
About 10% of cases. Due to multiple cerebral infarctions, performing a dementia chart with often abrupt onset, worsening in stages, with a semiology involving focal signs, in patients with vascular risk. It is necessary to look for a cardiovascular etiology that can help to stop evolution.
Dementia and expansive pathology of the CNS:
The three main causes are:
– Brain tumors, especially frontal ones.
– The subdural hematoma where the initial trauma can be minimal and forgotten.
– Hydrocephalus at normal pressure with its classic triad of intellectual deterioration, gait disorders and sphincter disorders.
Their diagnosis will be facilitated by a systematic brain scan.
Dementia integrating an array of general illness:
– Vitamin deficiencies: essentially alcoholic encephalopathies, Korsakoff syndrome, marked by predominant anterograde amnesia (vitamin B1 deficiency); diagnosis must be early and parenteral supplementation prolonged.Vitamin B12 and folate deficiency may also be responsible.
– Intoxications: rare, especially alumina gels in chronic dialysis patients.
– Endocrine diseases: especially Hashimoto encephalopathy (associated with autoimmune thyroiditis), but also slow adrenal insufficiency, pituitary insufficiency, chronic hypercalcemia, chronic hypoglycemia, hyponatremia, most often iatrogenic, but may also fit into a Schwartz-Bartter Syndrome.
– General syphilitic paralysis: should not be forgotten, diagnosed on the serology and the PL, an early treatment by penicillin being able to be effective.
– Other infectious diseases: In patients with AIDS, a dementia syndrome may be due to toxoplasmic encephalitis, Candida, CMV infection, cryptococcal disease or tuberculosis, but also to demyelination and specific microglial lesions.
Dementia after acute CNS suffering:
– Post-anoxic after cardiac arrest, coma, prolonged hypoglycemia.
– Post-traumatic: syndrome boxers “drunk” shots.
In sum, the etiological record must focus on finding a curable cause. In his absence, there is the problem of care, often very heavy for the family.