Höffding step and beyond: The impact of visual sensory impairment on cognitive performance in neuropsychological testing of survivors of acute methanol poisoning

BACKGROUND

Sensory deficits can result in limitations regarding how well neuropsychological test findings can be interpreted. Only a few studies have investigated the influence of vision alteration on neuropsychological tests. In 2012 the Czech Republic experienced mass methanol poisoning. Methanol metabolites cause histotoxic hypoxia to the optic nerve.

OBJECTIVE

In the current study, the effect of the toxic damage on the parts of the visual pathway on visual and non-visual neuropsychological measures was investigated using electrophysiological methods (visual evoked potential (VEP) and optical coherence tomography (OCT) with retinal nerve fibre layer (RNFL) thickness measurement.

METHODS

53 individuals who experienced methanol poisoning participated in this research (76% men; ages 24 to 74 years, mean = 43.8±14.6 years; education 11.9±1.4 years). Each participant underwent comprehensive neurological, ophthalmological, and neuropsychological examinations.

RESULTS

The results of mixed-effect models revealed significant small to a medium association between the Stroop test weak interference and Grooved Pegboard with the left eye global, nasal and temporal RNFL thickness. Also, medium associations between the Finger Tapping test and the Stroop test weak interference and OS temporal RNFL, right eye temporal RNFL, and the latency P1 of VEP in the left eye were significant.

CONCLUSION

The results of this study found a small to medium association (r = .15- .33; p = .010- .046) between RNFL thickness and cognitive visual test performance. Careful interpretation is suggested regarding results obtained from visual tests of the executive or motor functioning with participants with RNFL decrease or other types of early visual processing damage.

Idiopathic spinal cord herniation at the cervicothoracic junction level presenting with unilateral sensory symptoms

Idiopathic spinal cord herniation (ISCH) most commonly occurs through a ventral dural defect at the midthoracic levels with a predilection to affect middle-aged females. It can have various presentations, the most common of which are Brown-Séquard syndrome and spastic paraparesis. Due to its rarity in clinical practice, the diagnosis of ISCH can be challenging to physicians unfamiliar with this entity. We report an exceedingly rare case of ISCH at the C7-T1 intervertebral disc level in a 44-year-old male presenting with eight months of isolated unilateral sensory symptoms. The diagnosis was made based on the findings on the patient's magnetic resonance imaging of the spinal cord, including the presence of an extradural cerebrospinal fluid collection. Surgical reduction of the herniated segment and patching of the dural defect resulted in a remarkable clinical improvement beginning in the immediate postoperative period. Follow-up MRIs showed no sign of reherniation, and the patient remained asymptomatic after one year of follow-up. Early diagnosis and surgical intervention led to an excellent early outcome in this case. However, long-term follow-up is necessary to monitor for reherniation and relapse of the symptoms in ISCH patients.

Diagnosis and Management of Cognitive Concerns in the Oldest-Old

Purpose of review

The fastest-growing group of elderly individuals is the "oldest-old," usually defined as those age 85 years and above. These individuals account for much of the rapid increase in cases of dementing illness throughout the world but remain underrepresented in the body of literature on this topic. The aim of this review is first to outline the unique contributing factors and complications that must be considered by clinicians in evaluating an oldest-old individual with cognitive complaints. Secondly, the evidence for management of these cognitive concerns is reviewed.

Recent findings

In addition to well-established associations between impaired cognition and physical disability, falls, and frailty, there is now evidence that exercise performed decades earlier confers a cognitive benefit in the oldest-old. Moreover, though aggressive blood pressure control is critical earlier in life for prevention of strokes, renal disease, and other comorbidities, hypertension started after age 80 is in fact associated with a decreased risk of clinical dementia, carrying significant implications for the medical management of oldest-old individuals. The oldest-old are more likely to reside in care facilities, where social isolation might be exacerbated by a consistently lower rate of internet-connected device use. The COVID-19 pandemic has not only highlighted the increased mortality rate among the oldest-old but has also brought the increased social isolation in this group to the forte.

Summary

Differing from the "younger-old" in a number of respects, the oldest-old is a unique population not just in their vulnerability to cognitive disorders but also in the diagnostic challenges they can pose. The oldest-old are more likely to be afflicted by sensory deficits, physical disability, poor nutrition, frailty, and depression, which must be accounted for in the assessment of cognitive complaints as they may confound or complicate the presentation. Social isolation and institutionalization are also associated with impaired cognition, perhaps as sequelae, precipitants, or both. Ante-mortem diagnostic tools remain particularly limited among the oldest-old, especially given the likelihood of these individuals to have multiple co-occurring types of neuropathology, and the presence of neuropathology in those who remain cognitively intact. In addition to the symptomatic treatments indicated for patients of all ages with dementia, management of cognitive impairment in the oldest-old may be further optimized by use of assistive devices, augmentation of dietary protein, and liberalization of medication regimens for risk factors such as hypertension.

Medium- and long-term functional behavior evaluations in an experimental focal ischemic stroke mouse model

Cerebrovascular accident (CVA) is one of the leading causes of death and disability worldwide, as well as a major financial burden for health care systems. CVA rodent models provide experimental support to determine possible in vivo therapies to reduce brain injury and consequent sequelae. This study analyzed nociceptive, motor, cognitive and mood functions in mice submitted to distal middle cerebral artery (DMCA) occlusion. Male C57BL mice (n = 8) were randomly allocated to control or DMCA groups. Motor function was evaluated with the tests: grip force, rotarod and open field; and nociceptive threshold with von Frey and hot plate assessments. Cognitive function was evaluated with the inhibitory avoidance test, and mood with the tail suspension test. Evaluations were conducted on the seventh- and twenty-eighth-day post DMCA occlusion to assess medium- and long-term effects of the injury, respectively. DMCA occlusion significantly decreases muscle strength and spontaneous locomotion (p < 0.05) both medium- and long term; as well as increases immobility in the tail-suspension test (p < 0.05), suggesting a depressive-type behavior. However, DMCA occlusion did not affect nociceptive threshold nor cognitive functions (p > 0.05). These results suggest that, medium- and long-term effects of DMCA occlusion include motor function impairments, but no sensory dysfunction. Additionally, the injury affected mood but did not hinder cognitive function.

Understanding the Delusion of Theft

The elderly with dementing illness often present with psychotic symptoms such as delusions, but the thematic content of delusions in the elderly differs from that of delusions expressed by younger individuals, and can be pathognomonic of early dementia. The aim of this paper is to review the recent literature on the delusion of theft, the most prevalent delusion in the elderly, in order to arrive at a deeper understanding of its sources and to identify successful therapeutic approaches. The literature from 2000 to the present was searched on the Google Scholar database using relevant search terms. Several older classical papers were also referenced. Understanding the origins of the delusion of theft - multiple losses, attempts at attributing such losses to an outside source, attempts at reliving a happier past - helps in devising responses that are comforting to the patient. The distress that often accompanies the delusion of having been robbed can be decreased by nursing home improvements in the handling of personal possessions, by the correction of sensory deficits, and by the provision of activities that distract from loneliness. Attention to stimuli that trigger the delusion helps to limit its occurrence. Medications may help, but can sometimes make matters worse. Understanding that delusional thinking can arise from sensory and cognitive deficits is critical to empathic caregiving and also to the lessening of caregiver burden.

Improvement of sensory function after sequestrectomy for lumbar disc herniation: a prospective clinical study using quantitative sensory testing

BACKGROUND

Previous studies have investigated sensory recovery in patients with lumbar disc herniation using rather subjective methods. There have been no reports on changes of sensory function in patients suffering from a preoperative sensory deficit using quantitative sensory testing (QST). The aims of this prospective study were (1) to assess the recovery of preoperative sensory dysfunction after lumbar sequestrectomy and (2) to quantify the strength of relationship between a sensory deficit and the patient's quality of life.

METHODS

We applied the QST protocol of the German Research Network on Neuropathic Pain (DFNS) in fifty-two patients with a single lumbar disc herniation confirmed on MRI treated by lumbar sequestrectomy. Further evaluation included a detailed medical history, a physical examination, numeric rating scale for leg, EQ-5D questionnaire, and thermometer.

RESULTS

Disc surgery resulted in a significant reduction of leg pain and a significant gain of quality of life. Thermal, mechanical, and vibration perception thresholds showed an obvious side-to-side difference preoperatively (p < 0.005). An early recovery of mechanical and vibration perception thresholds was detected, whereas cold perception needed more than 6 months to recover (p < 0.05). Quality of life was independent from perception thresholds, but correlated significantly with pain reduction.

CONCLUSION

Our data clearly show that there is a subjective and quantifiable improvement in sensory dysfunction postoperatively. The current data suggest that a sensory dysfunction does not influence a patient's quality of life.

A central processing sensory deficit with Parkinson's disease

Parkinson's disease (PD) is a progressive degenerative disease manifested by tremor, rigidity, bradykinesia, and postural instability. Deficits in proprioceptive integration are prevalent in individuals with PD, even at early stages of the disease. These deficits have been demonstrated primarily during investigations of reaching. Here, we investigated how PD affects sensory fusion of multiple modalities during upright standing. We simultaneously perturbed upright stance with visual, vestibular, and proprioceptive stimulation, to understand how these modalities are reweighted so that overall feedback remains suited to stabilizing upright stance in individuals with PD. Eight individuals with PD stood in a visual cave with a moving visual scene at 0.2 Hz while an 80-Hz vibratory stimulus was applied bilaterally to their Achilles tendons (stimulus turns on-off at 0.28 Hz) and a ±1 mA bilateral monopolar galvanic stimulus was applied at 0.36 Hz. The visual stimulus was presented at different amplitudes (0.2°, 0.8° rotation about ankle axis) to measure: the change in gain (weighting) to vision, an intramodal effect; and a simultaneous change in gain to vibration and galvanic stimulation, both intermodal effects. Trunk/leg gain relative to vision decreased when visual amplitude was increased, reflecting an intramodal visual effect. In contrast, when vibration was turned on/off, leg gain relative to vision was equivalent in individuals with PD, indicating no reweighting of visual information when proprioception was disrupted through vibration (i.e., no intermodal effect). Trunk and leg angle gain relative to GVS also showed no reweighting in individuals with PD. These results are in contrast to previous results with healthy adults, who showed clear intermodal effects in the same paradigm, suggesting that individuals with PD not only have a proprioceptive deficit during standing, but also have a cross-modal sensory fusion deficit that is crucial for upright stance control.

Downregulation of the sodium channel Nav1.6 by potential transcriptomic deregulation may explain sensory deficits in critical illness neuropathy

AIMS

Sepsis patients and other patients in the critical care settings are at very high risk of mortality due to the primary illness. However, a fraction of patients, even after showing initial clinical improvement, deteriorates relentlessly at later stages. Increasingly, it is being identified that this is mostly due to dysfunction of the neurological system.

MAIN METHODS

We obtained peripheral nerve biopsies from the sural nerve from ICU patients. Nav1.6 expression was significantly diminished. The expression of cellular membrane anchoring protein for Nav1.6, ankyrin, remained unaffected, suggesting that genomic repression may be responsible for the diminished expression of the sodium channels. We examined the expression of two regulatory transcription factors: (a) a positive regulator YY1 that binds to the promoter region of sodium channels and (b) an upstream negative neuronal regulator REST.

KEY FINDINGS

REST expression was significantly elevated, while YY1 expression was diminished. Finally, we also observed that the cholinergic synthetic enzyme acyltransferase was also significantly diminished in sensory nerve lysates. Finally, circulating antibodies was detected in the peripheral blood against all the major sodium channels Nav1.6, 1.8 and 1.9, which contribute to the development and propagation of action potentials.

SIGNIFICANCE

This may potentially explain why its dysfunction affects neurological functions across all systems of the body during critical illness. The underlying mechanism of why the expression of the REST transcriptional factor is affected in critical illnesses remains our future goals of investigation.

Precision grip control, sensory impairments and their interactions in children with hemiplegic cerebral palsy: a systematic review

Children with hemiplegic cerebral palsy (HCP) exhibit long-term functional deficits. One of the most debilitating is the loss of prehension since this may impair functional independence. This loss of prehension could be partly due to sensory deficits. Identifying the underlying causes of prehension deficits and their potential link with sensory disorders is important to better adapt neurorehabilitation. Here we provide an overview of precision grip and sensory impairments in individuals with HCP, and the relation between them, in order to determine whether the sensory impairments influence the type and magnitude of deficits as measured by studies of prehensile force control. Pubmed and Scopus databases were used to search studies from 1990 to 2012, using combinations of the following keywords: fingertip force; grip force; precision grip; sensory deficit; sensory impairment; tactile discrimination; with cerebral palsy. Of the 190 studies detected through the systematic search; 38 were finally included in the systematic part of this review. This review shows that sensory deficits are common and are likely underestimated using standard clinical assessments in HCP. Some studies suggest these deficits are the basis of predictive motor control impairments in these individuals. However, children with HCP retain some ability to use predictive control, even if it is impaired in the more affected hand. Intensive practice and initial use of the less affected hand, which has only subtle sensory deficits, has been shown to remediate impairments in anticipatory motor control during subsequent use of the more affected hand. Implications for motor and sensory rehabilitation of individuals with HCP are discussed.