Management of cognitive impairment associated with post-COVID-19 syndrome: recommendations for primary care

Introduction: Although post-COVID-19 syndrome (PCS) with cognitive impairment is increasingly encountered in primary care, evidence-based recommendations for its appropriate management are lacking. Methods: A systematic literature search evaluating the diagnosis and treatment of cognitive impairment associated with PCS was conducted. Practical recommendations for the management of PCS-associated cognitive impairment in primary care are summarized, based on an evaluation of pharmacological plausibility and clinical applications. Results: Currently, the pathology of cognitive impairment associated with PCS remains unclear with no high-quality data to support targeted interventions. Existing treatment approaches are directed towards symptom relief where counseling on the chronicity of the disease and regular reassessments at 4- to 8-week intervals is considered reasonable. Patients should be informed and encouraged to adopt a healthy lifestyle that centers around balanced nutrition and appropriate physical activities. They may also benefit from the intake of vitamins, micronutrients, and probiotics. The administration of Ginkgo biloba extract could offer a safe and potentially beneficial treatment option. Other non-pharmacological measures include physiotherapy, digitally supported cognitive training, and, if indicated, ergotherapy or speech therapy. In most patients, symptoms improve within 8 weeks. If serious, ambiguous, or when new symptoms occur, specialized diagnostic measures such as comprehensive neurocognitive testing or neuroimaging should be initiated. Very few patients would require inpatient rehabilitation. Conclusion: PCS with cognitive impairment is a debilitating condition that could affect daily functioning and reduce work productivity. Management in primary care should adopt a multidisciplinary approach, centering around physical, cognitive, and pharmacological therapies.

Covid-19: Involvement of the nervous system. Identifying neurological predictors defining the course of the disease

The main objective of this study was to analyse neurological symptoms during a Covid-19 infection and determine the pattern of symptoms by comparing outpatients with inpatients. A further goal was to identify possible predictors, such as pre-existing conditions and neurological symptoms.

We recorded the clinical data of 40 inpatients and 42 outpatients in this retrospective, cross sectional study. Of them, 68 patients (83%), evenly distributed between the two groups, suffered from neurological symptoms. We identified the onset of neurological symptoms and the related time ranges in 41 patients (36 outpatients and 5 inpatients). Of these, 63.4% reported neurological symptoms on the first or second day of illness. 49 patients (72%) showed combinations of at least two to a maximum of seven different neurological symptoms. A more severe course of disease was correlated with age and male sex, but age was not identified as a predictor for the occurrence of neurological symptoms. Women suffered from central and neuromuscular symptoms more often than men (p = 0,004). The most common symptoms were fatigue (54%), headache (31%), loss of taste (31%), and loss of smell (27%).

Pre-existing dementia was associated with increased lethality; similarly, pre-existing stroke was associated with a more severe course of Covid-19 infection. Hallucinations and confusion were related to an increased likelihood of death.

The present data demonstrate the importance of comprehensive neurological support of inpatients and outpatients affected by Covid-19.

Spontaneous bilateral diaphragmatic paralysis: a rare cause of respiratory failure

Bilateral diaphragmatic paralysis (BDP) can occur in the course of motor neuron disease, myopathy, or from mechanical damage or the use of "ice slush" during cardiac surgery. BDP has been observed during and after infections, associated with systemic lupus erythematosus and mediastinal tumors, or may have idiopathic etiology. It is a serious and life-threatening condition. A 62-yr-old man presented with slowly progressive dyspnoea that worsened in the supine position and on bending forward. Chest X-rays, fluoroscopy, lung-function parameters and blood-gas analysis revealed respiratory failure. BDP was confirmed from a phrenic nerve stimulation test and measurement of transdiaphragmatic pressure (Pdi). Since there was no evidence of an obvious etiology, BDP was considered idiopathic. Other muscles were not involved. The pathological basis was probably focal demyelination in segments of the phrenic nerve. Because of increasing diaphragmatic muscle fatigue, the patient was treated with a nasal mask providing bi-level positive airway pressure (BiPAP) ventilation during the night. Clinical suspicion of BDP should always be raised in patients suffering slowly progressive dyspnoea without any obvious cardiac, metabolic or traumatic predisposing factors, and orthopnoea and dyspnoea on bending forward. Electromyographic tests and measurement of Pdi can reveal the correct diagnosis.

Epileptic seizures following cortical application of fibrin sealants containing tranexamic acid in rats

BACKGROUND

Fibrin sealants (FS) derived from human plasma are frequently used in neurosurgery. In order to increase clot stability, FS typically contain aprotinin, a natural fibrinolysis inhibitor. Recently, synthetic fibrinolysis inhibitors such as tranexamic acid (tAMCA) have been considered as substitutes for aprotinin. However, tAMCA has been shown to cause epileptic seizures. We wanted to study whether tAMCA retains its convulsive action if incorporated into a FS.

METHOD

FS containing aprotinin or different concentrations of tAMCA (0.5-47.5 mg/ml) were applied to the pial surface of the cortex of anaesthetized rats. The response of the animals was evaluated using electroencephalography and by monitoring the clinical behaviour during and after recovery from anaesthesia.

FINDINGS

FS containing tAMCA caused paroxysmal brain activity which was associated with distinct convulsive behaviours. The degree of these seizures increased with increasing concentration of tAMCA. Thus, FS containing 47.5 mg/ml tAMCA evoked generalized seizures in all tested rats (n=6) while the lowest concentration of tAMCA (0.5 mg/ml) only evoked brief episodes of jerk-correlated convulsive potentials in 1 of 6 rats. In contrast, FS containing aprotinin did not evoke any paroxysmal activity.

INTERPRETATION

Tranexamic acid retains its convulsive action within FS. Thus, use of FS containing tAMCA for surgery within or close to the CNS may pose a substantial risk to the patient.

[Proximal neuropathy of the median nerve]

In a 77 year old man the rare clinical picture of a complete lesion of the median nerve at the upper arm is described. During removal of a "neurinoma" at the upper arm, inadvertedly the general surgeon had also transsected the median nerve. However diagnosis was delayed due to electrodiagnostic tests, which erronously interpreted the volume conduction of the neigbouring nerves as partial function, and later even as improvement of the median nerve function. Clinically he presented with "orators" hand. He was unable to pinch thumb and index finger, Sensory loss was noted at the fingertip 2 and 3, atrophy of the abductor pollicis brevis muscle and trophic skin changes with an ulcer at the tip of the index finger. Nerve revision confirmed the median nerve transsection. Intraoperative nerve stimulation could not elicit distal muscle stimulation. Sural nerve transplant was performed and within one year a positive Tinel sign progressing 20 cm distally to the operation site, without distal motor or sensory changes was observed.

Dose-dependent effects of inspiratory muscle training in neuromuscular disorders

The goal of this study was to show whether a correlation exists between the intensity of specific respiratory muscle training and the improvement of strength and endurance in inspiratory musculature in patients with neuromuscular disorders (NMD). Sixteen patients with NMD (13 with Duchenne muscular dystrophy and 3 with spinal muscular atrophy) performed inspiratory muscle training (IMT) at home with a special training apparatus for 9 months. Maximal inspiratory mouth pressure (PI(MAX)) and 12s-maximum voluntary ventilation (12s-MVV) test served as parameters for inspiratory muscle strength and endurance, respectively. In patients whose inspiratory vital capacity (VC(in)) declined by less than 10% during the year before training began (n = 10), a significant positive correlation was found between the number of successfully completed strength and endurance exercises and the improvement of PI(MAX) (P < 0.05) and 12s-MVV (P < 0.05). In patients whose VC(in)-decline exceeded 10% (n = 6), indicating more progressive respiratory system involvement of the disease, no significant correlation between the improvement of PI(MAX) and 12s-MVV and the intensity of training was found. In patients with NMD, the effects of IMT-runs are dose-dependent, provided that the respiratory system involvement of the disease is only slowly progressive.

Iliac artery aneurysm causing isolated superior gluteal nerve lesion

Lesions of the superior gluteal nerve (SGN) lead to weakness of hip abduction, manifesting itself as a gait abnormality, with contralateral tilting of the pelvis with each step. Causes are numerous and may occur at different anatomical locations before the nerve enters the suprapiriform foramen, in the foramen itself, or after the nerve has exited the foramen. This case report describes an SGN lesion by a large iliac artery aneurysm in a patient presenting with a gait disorder.

[Role of electrophysiology in diagnosis of polyneuropathies]

Most for polyneuropathies present in a uniform, distally accentuated, rather symmetrical pattern, although asymmetric or multifocal distributions occur. The main feature of diagnosis is the history of development and the neurological clinical examination. Neurophysiologic studies, mainly nerve conduction studies (motor and sensory), reflex studies and electromyography are very accurate, but unspecific tools in order to establish the diagnosis of polyneuropathies, define special electrophysiologic features and can also reveal undetected (subclinical) lesions. For clinical purposes most neuropathies can be divided according the nerve conduction studies in axonal, demyelinating and mixed types. In recent years additional electrophysiological features as conduction block have appeared and are still under discussion. The etiology of polyneuropathy has to be determined in each patient with scrutinity. Additionally to general diseases (e.g. diabetes), common toxins (e.g. alcohol), concurrent medication (e.g. some cytostatic drugs) also immunologic (e.g. vasculitis) and hereditary factors have to be considered. A nerve biopsy is only indicated after a thorough consideration of electrophysiology and ancilliary findings. This applies in particular to hereditary neuropathies, where genetic testing has become a highly reliable test replacing biopsy.

Repetitive phrenic nerve stimulation study in normal subjects

In patients with myasthenia gravis (MG), it may be difficult to determine by clinical methods if respiratory insufficiency is due to a defect in neuromuscular transmission. We therefore studied the technique of repetitive electrical stimulation of the phrenic nerve in 6 healthy subjects. It was easily performed and quite reproducible. Responses at 3-Hz stimulation were recorded from surface electrodes of the ipsilateral hemidiaphragm, before and after exercise. We analyzed the percent decrement of the negative peak (NP) amplitude, area, and duration of the diaphragmatic compound muscle action potential (CMAP) between the first and the fifth or sixth potentials. The mean percentage change of the area was -2.2% (+/-4.3), and in all tests the change was <10.6%, yielding a normal range of <11%. The change in the NP amplitude was 12.1% (+/-8.3); in duration, the change was -8.7% (+/-9.6). Producing diaphragm fatigue did not change these results. The increase in amplitude and decrease in duration with little change in area, termed pseudofacilitation, may be due to shifts in the position of the diaphragm affecting volume conduction. The technique is a promising tool in the diagnosis of respiratory involvement from neuromuscular transmission disorders.

Electrophysiological monitoring in neurological respiratory insufficiency

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Vinorelbine-induced neurotoxicity in patients with advanced breast cancer pretreated with paclitaxel--a phase II study

Vinorelbine (VNB) shows high antitumoral activity in advanced breast cancer due to its high affinity for mitotic tubulin and differs from the other vinca alkaloids with regard to its low degree of neurotoxicity because of its low affinity for axonal tubulin. Preclinical data show the existence of different binding sites on tubulin for vinca alkaloids and paclitaxel (P), suggesting a lack of cross-resistance. Thus, VNB was chosen eligible for a phase II study to evaluate both the therapeutic efficacy and the toxicity of VNB in patients (pts) with advanced breast cancer failing first- or second-line chemotherapy with P. A total of 14 pts with advanced breast cancer pretreated with P were entered into the study. Therapy consisted of VNB at 30 mg/m2 diluted in 500 ml of normal saline given over 30 min after a minimal interval of 4 weeks since the last application of P. For the first four cycles, injections were repeated at 2-week intervals; thereafter they were repeated at 3-week intervals until evidence of progressive disease or severe toxicity developed. All but one pt was considered assessable for response and all pts were evaluable for toxicity. No objective response was observed; two pts showed no change in their disease. In four pts therapy had to be stopped because peripheral neurotoxicity increased from a pretherapeutic level after therapy with P from National Cancer Institute Common Toxicity Criteria (NCI-CTC) grade 1 (n = 3) and 2 (n = 1) to neurotoxicity grade 3 after 1, 2 (n = 2), and 3 cycles of therapy with VNB, respectively. In addition, constipation of grade 2 occurred in 10 pts. Hematologic toxicity was negligible. No other evaluable toxicity exceeded NCI-CTC grade 1. Both observations of this study, the complete resistance to VNB and the increase in peripheral neuropathy, let us assume the existence of a preclinically not anticipated but clinically relevant cross-resistance between these two spindle poisons and the presence of common functional targets. Therefore, P-pretreated pts should be excluded from consecutive VNB-containing therapies.

The respiratory system

Neurological disorders frequently contribute to respiratory failure in critically ill patients. They may be the primary reason for the initiation of mechanical ventilation, or may develop later as a secondary complication. Disorders of the central nervous system leading to respiratory failure include metabolic encephalopathies, acute stroke, lesions of the motor cortex and brain-stem respiratory centres, and their descending pathways. Guillan-Barré syndrome, critical illness polyneuropathy and acute quadriplegic myopathy are the more common neuromuscular causes of respiratory failure. Clinical observations and pulmonary function tests are important in monitoring respiratory function. Respiratory electrophysiological studies are useful in the investigation and monitoring of respiratory failure. Transcortical and cervical magnetic stimulation can assess the central respiratory drive, and may be useful in determining the prognosis in ventilated patients, with cervical cord dysfunction. It is also helpful in the assessment of failure to wean, which is often caused by a combination of central and peripheral nervous system disorders. Phrenic nerve conduction studies and needle electromyography of the diaphragm and chest wall muscles are useful to characterize neuropathies and myopathies affecting the diaphragm. Repetitive phrenic nerve stimulation can assess neuromuscular transmission defects. It is important to identify patients at risk of respiratory failure. They should be carefully monitored and mechanical ventilation should be initiated before the development of severe hypoxaemia.

Transcortical and cervical magnetic stimulation with recording of the diaphragm

Transcortical and cervical magnetic stimulation is a potential method of examining the central inspiratory pathway to phrenic motor neurons. The reliability and accuracy of this technique were studied. We performed magnetic stimulations of the cortex and cervical spinal cord with recording from both hemidiaphragms in 35 normal subjects using two different stimulation coils (90-mm circular coil and 70-mm figure-of-eight coil). Needle electrode recordings and ultrasound real-time documentation in 2 subjects excluded volume-conducted contaminations from adjacent chest wall and abdominal muscles. The effect of diaphragmatic facilitation (stimulation at the end of a deep breath) on latency, and amplitude were compared to the effect of hypothenar muscle facilitation. Normal ranges were established for: latency; central motor conduction time; amplitude; amplitude ratio between between peripheral and both cortical and cervical amplitude; and excitability threshold. The latencies were similar for both coils. The amplitudes were significantly higher, and excitability thresholds significantly lower for the 90-mm circular coil, indicating that this coil is preferable for transcortical diaphragmatic stimulations. The effect of facilitation was greater for hypothenar than diaphragmatic recordings. There was excellent right-left agreement for all measurements. Transcortical and cervical magnetic stimulation with recording from the diaphragm can be used routinely to diagnose and monitor patients with impaired central respiratory drive.

MRI in patients with general paresis

Few cases of MRI in neurosyphilis have been reported. We examined the value of MRI in patients with general paresis; MRI was performed on four HIV-negative patients with parenchymatous neurosyphilis. It demonstrated frontal and temporal atrophy, subcortical gliosis and, in one patient, increased ferritin in the basal ganglia. The progression of the lesions on MRI correlated well with the neuropsychiatric disturbances. The MRI findings correlated with the well-known neuropathological findings. This combination of pathological findings in neurosyphilis has not been described before and we suggest that MRI is of prognostic value in patients with general paresis.

Respiratory electrophysiological studies in Guillain-Barré syndrome

Respiratory failure is a common and potentially life threatening complication in patients with Guillain-Barré syndrome. The incidence of phrenic nerve involvement and the predictive value of phrenic nerve conduction and diaphragmatic needle EMG were studied in 40 patients with Guillain-Barré syndrome within the first three days of admission to hospital. The negative peak onset latency of the diaphragmatic compound muscle action potential (CMAP), and its amplitude, duration, and area were abnormal in 83%. The need for ventilation was correlated with diaphragmatic CMAP amplitude (P = 0.005), and area (P = 0.001), but not with latency or duration. Abnormalities in diaphragmatic needle EMG were found in 45%, mainly a decreased number of motor unit potentials. The abnormalities correlated with the need for ventilation (P = 0.013). Of the 40% who required ventilation, all had either abnormal phrenic conduction, abnormal diaphragmatic needle EMG, or both. Eighty one per cent of the ventilated patients had abnormal forced vital capacity on the day of the electrophysiological examination. The results indicate that phrenic nerve conduction studies and diaphragmatic EMG are useful in detecting respiratory involvement in patients with Guillain-Barré syndrome and in identifying those at risk of respiratory failure.

[Multifocal motor neuropathy with conduction block--a clinico-neuropathologic case report]

Descriptions on patients with multifocal motor neuropathy with conduction block (MMNCB), including histology, nerve fiber teasing and electron microscopy on nerve biopsy, are rare. We report a 64-year old female patient with progredient weakness of the upper extremities without sensory deficit. Electrophysiology shows conduction blocks up to 80% in several examined motor nerves. A biopsy of the sensory sural nerve reveals features of a mixed axonal and de- and remyelinating neuropathy. Thus sural nerve biopsy contributes here significantly to differential diagnosis and supports an immune mediated pathogenesis of MMNCB.

Diaphragmatic paresis in newborns due to phrenic nerve injury

Phrenic nerve lesions as a result of birth trauma have been reported as a cause of acute respiratory distress infrequently. We report recent diagnostic and therapeutic experiences in four newborns with birth-traumatic phrenic nerve injury: one bilaterally, and three unilaterally, all right-sided. In each case, mechanical ventilation was required for at least 16 days. Ultrasound examination of the diaphragm and phrenic nerve conduction studies turned out to be the diagnostic methods of choice. Spontaneous recovery occurred in two children and two became asymptomatic after operative treatment. One improved after plication of diaphragm and one after autologous nerve transplantation.

Phrenic neuropathy in chronic renal failure

BACKGROUND

Peripheral neuropathy and alterations in diaphragmatic muscle function are frequently caused by uraemia. Phrenic nerve function in patients with end stage renal failure, however, has not been examined to date.

METHODS

An electrophysiological study of the phrenic nerve was performed to determine its possible involvement in 32 nondiabetic patients with end stage renal disease undergoing chronic haemodialysis.

RESULTS

Seventeen patients had electrophysiological signs of peripheral neuropathy in at least one of the investigated nerves and 14 of the 17 showed pathological phrenic nerve latencies. Delayed phrenic nerve latencies correlated clearly with pathological peroneal nerve conduction velocities.

CONCLUSIONS

Phrenic neuropathy is a frequent complication of uraemia.

Jarisch-Herxheimer reaction in a patient with neurosyphilis

A 40 year old man presented with progressive personality changes in the previous six months. Specific serological tests for syphilis in blood and CSF were highly positive and CSF sedimentation showed signs of an inflammatory process. Ten hours after the start of penicillin treatment a severe symptomatic Jarisch-Herxheimer reaction with alteration of level of consciousness, pupillary changes, and focal neurological signs developed. Jarisch-Herxheimer reaction may occur in various settings, particularly in the treatment of syphilis. Investigation of CSF before the treatment may predict a potential risk. Corticosteroid treatment has been suggested for prevention.

The effect of aminophylline on the force-length characteristics of the diaphragm

The aim of our study was to evaluate the effect of aminophylline on the contractile function of the human diaphragm during varying muscle fiber length. Ten healthy subjects were studied during maximal sniff maneuvers and bilateral phrenic nerve twitch stimulations, with and without intravenous infusion of aminophylline in a randomized fashion. The transdiaphragmatic pressures generated at various baseline lung volumes, from residual volume to 90% of total lung capacity, were recorded before and after the induction of diaphragm exhaustion. At all levels of lung volume, aminophylline did not have an effect on the contractility of the fresh diaphragm. In the exhausted diaphragm, however, the pressure values, induced by sniffs and twitch stimulations, were significantly improved by aminophylline. This positive effect on diaphragm contractility was also impressive at 60, 75, and 90% of total lung capacity. This indicates that aminophylline significantly improves the contractile function of the exhausted human diaphragm, even if the muscle fibers are shorter than optimal. This effect occurs regardless of the neuronal firing rate, whether it is low (twitch stimulation) or high (sniff maneuver).

Effect of lung transplantation on diaphragmatic function in patients with chronic obstructive pulmonary disease

BACKGROUND

To date there are no data on the effects of lung transplantation on diaphragmatic function in patients with end stage chronic obstructive pulmonary disease (COPD). It is not known whether the relation between the transdiaphragmatic pressure (PDI) and lung volume is altered in recipients after transplantation as a result of changes in diaphragmatic structure caused by chronic hyperinflation. The effect of lung transplantation on diaphragmatic strength was determined in patients with COPD and the relation between postoperative PDI and lung volume analysed.

METHODS

Diaphragmatic strength was assessed in eight double lung transplant recipients, six single lung transplant recipients, and in 14 patients with COPD whose lung function was similar to those of the transplant recipients preoperatively. PDI obtained during unilateral and bilateral phrenic nerve stimulation at 1 Hz (twitch PDI) at functional residual capacity (FRC) and during maximal sniff manoeuvres (sniff PDI) at various levels of inspiratory vital capacity (VCin) served as parameters for diaphragmatic strength. Sniff PDI assessed at the various VCin levels were used to analyse the PDI/lung volume relation.

RESULTS

Lung transplantation caused a reduction in lung volume, especially in the double lung transplant recipients. As a consequence sniff PDI was higher in the double lung transplant recipients than in the patients with COPD at all levels of VCin analysed. However, sniff PDI values analysed at comparable intrathoracic gas volumes were not reduced in the patients with COPD when compared with those who underwent lung transplantation. Bilateral twitch PDI values were similar in the patients with COPD and in the lung transplant recipients. In the single lung transplant recipients unilateral twitch PDI values were similar on the transplanted and the non-transplanted side. The relation between PDI and lung volume was similar in the patients with COPD and in the lung transplant recipients.

CONCLUSIONS

In patients with COPD lung transplantation leads to an increase the maximal sniff induced PDI values by placing the diaphragm in a more favourable position for pressure generation. Since patients with COPD and postoperative lung transplant recipients showed similar PDI/lung volume relations, this suggests that chronic pulmonary hyperinflation does not cause major functional alterations of the diaphragm.

Syndrome of continuous muscle fiber activity and plasmacytoma with IgM paraproteinemia

A patient with IgM-lambda plasmacytoma presented with continuous muscle fiber activity syndrome (CMFAS), which responded to carbamazepine therapy. This is the first report of CMFAS in association with plasmacytoma and IgM paraproteinemia.

[Necrotizing myopathy with antilipemic agents. Case report and review of the literature]

A 73 year old male who had been prescribed fenofibrate for years developed a slightly asymmetric paraparesis of both lower extremities. CPK values rose to 9800 U/l, EMG of the quadriceps femoris muscle was myopathic. Muscle biopsy revealed a necrotic myopathy. Discontinuation of fenofibrate induced a rapid decline of CPK values, followed by a slower remission of muscular symptoms and persisting pseudo-myotonic discharges in EMG. The spectrum of neuromuscular side effects of cholesterol lowering agents, consisting of myalgia, cramps and reversible CPK elevation, is discussed. Only rarely necrotic myopathies have been described.

Occurrence of epileptiform activity in the routine EEG of epileptic patients

In a retrospective study, the occurrence of epileptiform activity (EA) in routine EEG records of epileptic patients was investigated. Data were obtained from 1078 EEGs of 373 patients (199 men and 174 women; aged 17-87 (mean 34.2 +/-14.7)). The percentage of 38% of patients with EA in a single EEG could be increased to 77% by repeated records. After the 5th record however, the gain in new information decreased remarkably. No differences between seizure types could be detected. There was a relationship between EA and nonspecific EEG abnormalities. High EA rates were found for short time intervals since last seizure, young patients, long durations of the seizure disorder and for high seizure frequencies.