Background Deformational plagiocephaly (DP) is one of the most prevalent abnormal findings in infants and a frequent reason for parents to seek paediatric advice. Objective To systematically review the literature and identify evidence and hypotheses on the aetiology and determinants of DP in otherwise healthy infants. Design Systematic keyword search in all major biomedical databases to identify peer-reviewed publications reporting (a) empirical research or (b) hypotheses on the aetiology of DP in healthy, term infants. 3150 studies published between 1985 and 2016 and containing relevant keywords were screened. In a two-pronged approach, results were summarised separately for the body of empirical work (22 studies) and the body of hypotheses (110 articles). Review findings Only a few empirical studies have examined risk factors in non-selected patient populations on a higher grade methodological level. The most commonly reported risk factors were: male gender, supine sleep position, limited neck rotation or preference in head position, first-born child, lower level of activity and lack of tummy time. Agreement between empirical studies was poor for most exposures, including supine sleep position, tummy time and use of car seats. The articles reporting hypotheses on the aetiology of DP cover a wide field of environmental and biological factors, but include little suggestions as to the potential influence of the everyday care environment of the baby. Conclusions and relevance The evidence on the aetiology of DP is fragmentary and heterogeneous. In addition, factors possibly relevant to the development of DP have not been appreciated in the scientific discussion.

Although myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has a specific and distinctive profile of clinical features, the disease remains an enigma because causal explanation of the pathobiological matrix is lacking. Several potential disease mechanisms have been identified, including immune abnormalities, inflammatory activation, mitochondrial alterations, endothelial and muscular disturbances, cardiovascular anomalies, and dysfunction of the peripheral and central nervous systems. Yet, it remains unclear whether and how these pathways may be related and orchestrated. Here we explore the hypothesis that a common denominator of the pathobiological processes in ME/CFS may be central nervous system dysfunction due to impaired or pathologically reactive neuroglia (astrocytes, microglia and oligodendrocytes). We will test this hypothesis by reviewing, in reference to the current literature, the two most salient and widely accepted features of ME/CFS, and by investigating how these might be linked to dysfunctional neuroglia. From this review we conclude that the multifaceted pathobiology of ME/CFS may be attributable in a unifying manner to neuroglial dysfunction. Because the two key features – post exertional malaise and decreased cerebral blood flow – are also recognized in a subset of patients with post-acute sequelae COVID, we suggest that our findings may also be pertinent to this entity.

Zusammenfassung: Myalgische Enzephalomyelitis/Chronisches Fatigue-Syndrom (ME/CFS) ist eine schwere, chronische Multisystemerkrankung, die je nach Ausprägung zu erheblichen körperlichen und kognitiven Einschränkungen, zum Verlust der Arbeitsfähigkeit bis hin zur Pflegebedürftigkeit einschließlich künstlicher Ernährung und in sehr schweren Fällen sogar zum Tod führen kann. Das Ziel dieses D-A-CH-Konsensusstatements ist es, 1) den aktuellen Wissensstand zu ME/CFS zusammenzufassen, 2) in der Diagnostik die kanadischen Konsensuskriterien (CCC) als klinische Kriterien mit Fokus auf das Leitsymptom post-exertionelle Malaise (PEM) hervorzuheben und 3) vor allem im Hinblick auf Diagnostik und Therapie einen Überblick über aktuelle Optionen und mögliche zukünftige Entwicklungen aufzuzeigen. Das D-A-CH-Konsensusstatement soll Ärzt:innen, Therapeut:innen und Gutachter:innen dabei unterstützen, Patient:innen mit Verdacht auf ME/CFS mittels adäquater Anamnese und klinisch-physikalischen Untersuchungen sowie der empfohlenen klinischen CCC zu diagnostizieren und dabei die präsentierten Fragebögen sowie die weiteren Untersuchungsmethoden zu nutzen. Der Überblick über die zwei Säulen der Therapie bei ME/CFS, Pacing und die symptomlindernden Therapieoptionen sollen nicht nur Ärzt:innen und Therapeut:innen zur Orientierung dienen, sondern auch Entscheidungsträger:innen aus der Gesundheitspolitik und den Versicherungen darin unterstützen, welche Therapieoptionen bereits zu diesem Zeitpunkt bei der Indikation „ME/CFS“ von diesen erstattbar sein sollten.

Lay Summary: In industrialized societies some babies develop flattening of the back part of their head. It is thought that this comes from sleeping supine, which has been shown to be the safest option for babies. However, this explanation cannot be correct from an evolutionary standpoint: why should safe sleep come at the cost of a misshaped head? Babies in industrialized societies are generally healthy. The medical problems they may be afflicted with are usually well understood. Deformational plagiocephaly presents a notable exception. In many industrialized countries, one in six babies shows posterior flattening of the skull—a feature noteworthy from an evolutionary perspective as the well rounded cranium is part of the ‘Kindchenschema’ evolved to secure care for the infant. It is commonly held that the deformation of the posterior cranium occurs as a consequence of the supine sleep position, now advocated as the safest sleep position for babies by medical experts. This explanation, however, does not fare well in the light of evolutionary theory: why should safe sleep come at the cost of a social handicap? Here, we present an alternative hypothesis that is grounded on evolutionary mismatch theory and exemplifies how evolutionary reasoning can help clarify medical conditions relevant to today’s public health.