Editorial
In 1998, Macdonald Critchley and Eileen Critchley published their biography of John Hughlings Jackson (see Brain, 1999; 122: 1199–200). Then in his 98th year, Macdonald Critchley drew on the personal accounts of many from whom he had learned neurology, themselves taught and directly influenced by Hughlings Jackson. Dubbed by Dr and Mrs Critchley as the ‘Father of English Neurology’, the senior author was therefore, in a sense, one of Hughlings Jackson's ‘neurological grandsons’ by direct descent. Their shrewd and informative account is rich in personal and genealogical details, and in its critical appraisal of Hughlings Jackson's writings. He was not an experimentalist but used clinical observation to understand organizational principles in the nervous system. Hughlings Jackson was influenced by colleagues at the West Riding Lunatic Asylum (see Brain 2007; 130: 599–601) and the philosopher Herbert Spencer. He believed that function is not localized but depends on complex orchestration of the entire nervous system, even though disorder at specific sites yields precise and predictable clusters of clinical deficits. Behind this rather pragmatic view of cerebral localization lay a more sophisticated philosophy which, in its fully developed formulation, postulated three layers of organization. In disease, subservient systems in this hierarchy are released creating syndromes consisting of negative (loss of function) and positive (disinhibited) symptoms. The lowest level is concerned with vegetative function and operates through reflex activity at the spinal level: the next tier (cortex, striatum and long tracts) determines movement and sensation; and the most elevated system is the pre-frontal region providing higher functions and coordination of the more elementary components. Hughlings Jackson is revered but largely unread. He left no major synthesis of his views and reading the papers requires detective work and stamina. We dedicated an issue to Hughlings Jackson in March 1907 (with papers on the cerebellum by Hughlings Jackson himself, Sherrington, Edinger, Batten, Farquhar Buzzard, Holmes and Kinnier Wilson; and by Head and Thompson on afferent impulses in the spinal cord—running to a mere 204 pages), and reprinted 15 papers on aphasia in 1915 (Brain 38: 1–190) with a critique by Henry Head and a bibliography listing 36 articles published between 1864 and 1893. James Taylor edited Hughlings Jackson's Neurological Fragments (1925) and, with the help of Gordon Holmes and FMR Walshe, published on behalf of the Guarantors of Brain his Selected Writings (1931–1932), each with a bibliography of papers published between 1861 and 1909; the Critchleys identified some other publications but a definitive bibliography has been lacking. Now, George York and David Steinberg fill the gap with An introduction to the life and work of John Hughlings Jackson with a catalogue raisonné of his writings (Medical History 2006; 52 Suppl 26: p 165). Errors in the lists compiled by James Taylor are corrected, and 84 publications not previously catalogued added to the Jacksonian canon. In ‘The philosopher of emerging clinical neurology’ (page 1968), Mervyn Eadie explains the principles of Hughlings Jackson's hierarchial system based on sensory-motor reflexes that so much influenced Sir Charles Sherrington (Brain 2007; 130: 884–886), and his views on epilepsy and cortical localization (‘I am not what has been called a universaliser ... nor am I a localizer’). Professor Eadie accepts that not all Hughlings Jackson's ideas were original; he notes the tendency for loose ends to be left untied as Hughlings Jackson moved on to new interests; and he shares in the general view that Hughlings Jackson's prose is awkward and his writings inaccessible. As professor emeritus of neurology in the University of Brisbane, historian of Australian neurology (in papers published from 1981) and scholar on the origin of ideas and concepts concerning epilepsy (writing extensively on this topic since 1989) Professor Eadie is well qualified to comment. This is an affectionate and constructive appraisal for, taken together, Mervyn Eadie acknowledges and trumpets Jackson's genius, and finds the pedestal on which posterity placed him when he died in 1911 to have rock-solid foundations. Sadly, though the pedestal remains intact, the bust of Hughlings Jackson which it supported was removed some years ago from the front hall of Queen Square evidently by an unknown neurophilic kleptomaniac.Often, like London buses, not many papers on a particular topic are submitted and then several come in a rush. The present issue contains five from amongst a number considered recently that describe those aspects of syndromes converting from one phenotype to another, or evolving from detectable but pre-symptomatic forms of a particular disease. John Ringman and colleagues from Los Angeles, Sylmar and Downey (USA) and Mexico City (Mexico) studied white matter changes in individuals at risk of familial Alzheimer's disease using diffusion tensor imaging of strategic white matter regions (page 1767): they find that fractional anisotropy of late-myelinating tracts connecting limbic structures, especially the fornix, characterizes pre-symptomatic familial Alzheimer's disease, and this feature may merit evaluation as a biomarker in sporadic forms of the disease. Jennifer Whitwell and investigators from the Mayo Clinic (Rochester, USA) studied patients with mild cognitive impairment, and charted changes in regional brain atrophy in the 3 years before conversion to Alzheimer's disease (page 1777): they show an evolution from early changes in the medial temporal lobes and fusiform gyrus spreading to involvement of the posterior temporal lobe and hippocampus, and then the temporoparietal association cortex and frontal lobes by the time of clinical conversion to Alzheimer's disease—matching the known pathological maturations and providing another potential biomarker of overt dementia. Yen Tai and a team from Imperial College and the Institute of Neurology (London, UK), Cambridge (UK) and Mainz (Germany) use 11C-(R)-PK11195 positron emission tomography to compare microglial activation and striatal neuronal dysfunction (11C-raclopride) in pre-symptomatic Huntington's disease (page 1759): they show increased microglial activation in the presence of decreased striatal neuronal activity at the time of conversion to overt disease and with further progress across the initial clinical course—findings that tell us something of the early pathogenesis and provide another potential biomarker for incipient dementia. Caroline Williams-Gray and colleagues from Cambridge (UK) add to previous work from the group of Roger Barker (esteemed editor of Advances in Clinical Neuroscience and Rehabilitation) on cognitive failure in a subset of patients from an incident cohort with Parkinson's disease further documenting cognitive profiles in the early (3–5) years of the disease (page 1787): they reveal a sharp increase in deficits, especially those implicating frontostriatal functions and depending on the integrity of posterior cortical structures, that reaches 67% at a mean 3.7 years from onset; now, we need to know if these cases can be predicted by genetic profiles or other features that illuminate the nature of cognitive failure in Parkinson's disease and account for its apparent heterogeneity. Kevin Strauss and investigators from Strasburg and Pasadena (USA) studied Amish individuals with glutaryl-CoA dehydrogenase deficiency (page 1905): they show impaired glucose uptake and increased grey matter blood volume in pre-symptomatic individuals, and describe three stages of striatal necrosis characterized by acute cytotoxic oedema, subacute reduced striatal perfusion and glucose utilization, and chronic striatal atrophy, respectively—these events developing insidiously or ushered in by illnesses early in life for which intravenous fluids and dextrose might prove neuroprotective.
One other paper also deals with mitochondrial disease. Edoardo Malfatti and investigators from Milan and Siena (Italy) and Porto Alegre (Brazil) have undertaken an heroic screen of mitochondrial and nuclear encoded genes in a large sample of paediatric and adult cases with encephalopathy due to complex 1 deficiency (page 1894): they identify new mutations of mitochondrial DNA that affect NADH-dehydrogenase (ND) components of complex 1 function, examine for functional deficits in mitochondrial cybrids and show impaired assembly of the holoenzyme complex implying that these are pathogenic mutations and surprisingly common explanations for complex 1 deficiency in all age groups. The syndrome of intracranial hypotension and radiological features of the spontaneous variant are well recognized but the mechanism not so well understood. On page 1884, Mario Savoiardo and colleagues from Milan (Italy) show that brain swelling in patients with spontaneous intracranial hypotension occurs only in those with diffusion abnormalities that affect structures draining into the vein of Galen and straight sinus: they describe a decreased angle between these vessels that results in functional stenosis at their junction, perhaps thereby explaining the abnormalities of brain volume that may occur in idiopathic intracranial hypotension. Darcy Reisman and investigators from Newark (USA) seek to provide a physiological rationale for rehabilitation aimed at improving gait after stroke (page 1861). The issue is whether cerebellar circuits that also involve cerebral structures are required for both fast and slow adjustments to gait patterns required during walking. The answer is ‘no’; these involve only brainstem–cerebellar connections. But, in passing, 15 min adaptation to perturbations of terrain on a split-belt walking treadmill corrects baseline asymmetry of spatio–temporal gait abnormalities, suggesting this as a useful rehabilitation strategy.
Three papers focus on the temporal lobe. Ingrid Olson, Alan Plotzker and Youssef Ezzyat from Philadelphia (USA) review the role of the temporal pole in social and emotional processing, drawing on the human and non-human primate literature and emphasizing functions over and above memory (page 1718, and see cover): they argue that this part of the brain acts to bind complex perceptual inputs to visceral emotional responses feeding into specific streams that support the special senses—dorsal (auditory), medial (olfactory) and ventral (visual). Valérie Rigau and colleagues from Montpellier (France) examine blood vessels in the temporal lobes of patients undergoing epilepsy surgery (page 1942): first, they show that seizure frequency is associated with increased expression of vascular endothelial factor, damage and leakage of the blood brain barrier and angiogenesis—findings that are reproduced in a rodent model of temporal lobe epilepsy, leading to the conclusion that seizure-driven vascular changes contribute to further neuronal dysfunction and perpetuation of the seizure pattern. Carmen Barba and investigators from Rome and Florence (Italy) and Grenoble (France) characterize the clinical features of patients with temporal lobe epilepsy dependent on electrical discharges confined to the temporal lobe and those extending to nearby structures with which the temporal lobe makes connections (page 1957): indistinguishable in many respects, patients with discharges in the extended network—defined by intracerebral recordings and interictal electroencephalography—more frequently exhibit adversive head and eye postures, and describe gustatory, auditory and vestibular sensations, autonomic experiences and mood changes in association with their attacks. Thus, back to John Hughlings Jackson and his magisterial contributions to neurology through observing people with the ‘dreamy state’ that accompanies seizures arising from the temporal lobes (however, these are currently classified). In From the Archives we review ‘On right or left sided spasm at the onset of epileptic paroxysms, and on crude sensation warnings, and elaborate mental states’ (J Hughlings Jackson, Brain 1880; 2: 192–206); ‘On a particular variety of epilepsy ("intellectual aura"), one case with symptoms of organic brain disease (J Hughlings Jackson, Brain 1888; 11: 179–207); ‘Case of epilepsy with tasting movements and "dreamy state"—very small patch of softening in the left uncinate gyrus’ (J Hughlings Jackson and WS Colman, Brain 1898; 21: 580–90); and ‘Epileptic attacks with a warning of a crude sensation of smell and with the intellectual aura (dreamy state) in a patient who had symptoms pointing to gross organic disease of the right temporo-sphenoidal lobe’ (J Hughlings Jackson and Purves Stewart, Brain 1899; 22: 535–49).
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