Front Neurol Neurosci

[Denisha Padley]

ObjectivesIdentify the most common etiology of anosognosia in patients with neurological and psychiatric disorders.Describe the evaluation of patients with anosognosia.Outline the treatment and management options available for patients with anosognosia.Explain interprofessional team strategies for evaluating, managing, and educating patients and their families about anosognosia.Access free multiple choice questions on this topic.

Anosognosia is a neuropsychiatric condition in which one is in denial--unconsciously--and unaware of an apparent disability or deficit. The French neurologist, Joseph Babinski, first described anosognosia when highlighting the obliviousness of those afflicted with left hemiplegia, in 1914.[1] Anosognosia can manifest transdiagnostically as it is extant in both psychiatric and neurologic disorders. Most often, it precipitates in the setting of structural damage--from ischemic strokes--to the right parietal cortex. It also has utility as a psychiatric construct used to describe a patient's lack of insight.[2]

Typically, as mentioned in the introduction, anosognosia manifests as a neurological sequela following an injury or a lesion to the right parietal lobe; however, the two are not mutually exclusive as the phenomenon of anosognosia can occur with temporoparietal, thalamic, or basal ganglia lesions, as well as in psychiatric disorders. The exact etiology of anosognosia is unknown but is likely due to a derangement of the anatomical or functional monitoring unit that mediates the conscious awareness of deficits. The most likely physiopathologic mechanism is that the brain lesion that causes anosognosia disrupts neurocognitive, secondary integration areas.[3] Structural and functional regions under investigation include the prefrontal cortex (involved in working memory, self-monitoring, and organization), insular cortex (associated with the salience network, emotional processing, and error awareness), and default mode network (includes connectivity between prefrontal, parietal, and cingulate cortices). Damage to these areas can lead to a lack of conscious awareness of cognitive or sensorimotor function loss.

Anosognosia can occur after acute brain injuries such as strokes or traumatic brain injuries, and can also occur in the absence of any putative brain injury. In stroke patients with hemiparesis, the incidence of anosognosia is 10% to 18%.[4] The term anosognosia can also refer to the lack of awareness seen in psychiatric conditions when patients deny or minimize psychiatric symptoms. It is estimated that 50-90% of patients with schizophrenia and 40% of patients with bipolar disorder demonstrate anosognosia or severe lack of insight.[5] In the setting of neurocognitive disease, 60% of patients with mild cognitive impairment[6] and 81% of patients with Alzheimer's dementia appear to have some form of anosognosia; patients suffering from these conditions deny or minimize their memory impairment.[7]

Patients with anosognosia due to brain injury often exhibit a lack of awareness of hemiparesis, hemisensory deficits, memory deficits, and language deficits. Patients may be unaware of one deficit while recognizing others. Anosognosia can co-occur with somatosensory neglect (asomatognosia), which also localizes to the right parietal lobe. The latter consists of the patient's denial that part of their body belongs to them.

Although anosognosia usually accompanies a right parietal, temporoparietal, thalamic, or basal ganglia lesion, recent studies suggest that the deficit sometimes can relate to non-structural changes. These changes cause problems with the connectivity of different parts of the brain.[8]

The fundamental neurophysiologic or psychopathologic problem in anosognosia relates probably to an inability of the patient to update their self-image. Because of a lesion in the brain or dysfunction due to illness, the patient cannot incorporate new information regarding their deficits into their self-image. Therefore, they deny their illness or deficit or downplay its significance.

When anosognosia is due to structural brain damage, neuroradiological findings typically show damage to the right parietal or right temporoparietal region. Less common are lesions in the thalamus, basal ganglia, or left parietal region. Neuroimaging in dementia typically shows more global brain atrophy. Neuroimaging in psychiatric disorders usually shows non-specific findings.

There is no specific treatment for anosognosia, but vestibular stimulation seems to improve this condition temporarily. This maneuver probably influences awareness of the neglected side temporarily. Where anosognosia persists, cognitive therapy can help patients better understand and compensate for their deficit.

Anosognosia differs from denial, a psychological defense mechanism that involves avoiding or rejecting information that provokes stress or pain. With denial, the patient may acknowledge a deficit but minimize its consequences and avoid treatments geared to remedy the deficits. Anosognosia also differs from a more global derangement such as encephalopathy where there may be problems with wakefulness and attention. It differs from other deficits such as visual, sensory, and cognitive deficits which limits the ability of patients to realize their deficit.

When anosognosia is due to a focal structural lesion of the brain, it typically resolves over time, though it can persist over the long-term. When anosognosia is due to mental illness or dementing illness, it may persist and lead to poor compliance with medication regimens.

Anosognosia can impair rehabilitation and recovery because patients that lack awareness of a deficit may show less inclination to take part in rehabilitation therapy to tackle the neurological dysfunction. Patients with anosognosia also may suffer more frequent falls due to their lack of awareness of their deficits. Health providers may need to take safety precautions that they see fit in order to avoid injury.

Recently A.R. Egbert described an ethical framework to involve patients with anosognosia in their rehabilitation treatment.[9] Rehabilitation specialists must always think of and consider this condition because it may affect the outcome of their treatment plan.

Education on how to deal with and help avoid problems related to anosognosia for patients and family members of the patients with this dysfunction is of utter importance, and lack of collaboration from the sufferer is typical due to the patient's failure to acknowledge or minimization of their condition. Issues such as driving, handling money, and walking without help may become areas of conflict. It is important to do a thorough safety evaluation to avoid injury to the patient suffering from anosognosia. Simplifying tasks, maintaining a positive approach, showing concern and empathy, and providing a structured environment are helpful to avoid negative outcomes.

It is very important for emergency medicine clinicians to know of anosognosia. For example, in the setting of acute stroke, the timing of symptom onset is crucial to the administration of thrombolytic therapy. If the patient is unaware of their deficit, they may not give accurate information on the exact time of stroke symptom onset. In this situation, collateral history from a family member is crucial to making an informed treatment decision.

The management of anosognosia is very difficult. Because there are many causes, the management is with an interprofessional team that includes a neurologist, psychiatrist, mental health nurse, primary care physician, and a psychotherapist. There is no specific treatment for anosognosia, but vestibular stimulation seems to improve this condition temporarily. This maneuver probably influences awareness of the neglected side temporarily. Where anosognosia persists, cognitive therapy can help patients better understand and compensate for their deficit. If the cause is a stroke, dementia, or a mass lesion, the prognosis in most cases is poor. If the cause is related to a mental health disorder, the condition leads to difficulty in medication compliance. The overall quality of life is poor.[10]

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Finally, two DBS patients (one with PD and OCD each) were prospectively reprogrammed, and one OCD patient was prospectively implanted and programmed as informed on the streamline models established here (see below for more detailed case vignettes).

Disease-wise stimulation effects were mapped into anatomical space at the subthalamic level. A caudo-rostral latero-medial organization emerged for peak voxels associated with beneficial stimulation ranging from DYT to TS, PD and OCD (Fig. 3, center). This result was consistent with functional zones commonly associated with anatomical portions of the nucleus (DYT in the sensorimotor, TS in the motor, PD in the motor-premotor and OCD in the associative-limbic domain). A detailed overview of the anatomical localization of sweet and sour spots for each disease is provided in Fig. 3 (top and bottom panels). Peak voxel coordinates are reported in Supplementary Table 9.

Spatial correlations between electric fields (E-fields) and the optimal pattern were performed to confirm that the sweet spot model could explain variance in clinical outcomes (Fig. 3, middle panel, left and right). This analysis was carried out (1) to compare results between disorders and (2) to compare amounts of variance accounted for by sweet spots versus sweet streamlines. Critically, these in-sample analyses were circular in nature and should, thus, not be overinterpreted. To account for this limitation, analyses were subjected to fivefold cross-validation (CV) (Fig. 3, middle panel, left and right) to investigate generalizability of findings, which yielded significant results in all disorders but TS (with the lowest n). To demonstrate stability of sweet spot configurations and fivefold CVs across different E-field thresholds, we repeated the procedure with varying thresholds, which led to consistent results (Supplementary Fig. 1).

3a8082e126