Brain, Vol. 126, No. 2, 508-511,
February 2003
© 2003 Guarantors of Brain
doi: 10.1093/brain/awg024
Book Review |
A DICTIONARY OF NEUROLOGICAL SIGNS
Walsgrave Hospital, Coventry, UK
A DICTIONARY OF NEUROLOGICAL SIGNS
By A. J. Larner
2001. Dordrecht: Kluwer Academic Publishers
Price £19. ISBN 140200043X.
In the early 1960s a live BBC television broadcast on Parkinson’s disease showed the moment of cessation of tremor in a patient undergoing stereotactic surgery. The importance of the physical sign not only in diagnosis but also, together with knowledge of anatomy, in understanding pathophysiology was made clear and a future addiction to physical signs primed in at least one viewer. Subsequent medical school training saw exhaustive exposure. The professorial medical ward round would start in the post mortem room at 1:30 pm, subsequently progressing to the ward, symptoms and signs continuing to be dissected until the medical school bar opened at 6:00 pm. A missed opportunity to examine a patient led to professorial admonishment, permanently recorded in the medical school journal, that ‘time tide, and signs in the chest wait for no man’ but encouragement led to the rare opportunity to observe a patient in circulatory failure, alternately blue, gasping for breath yet pink and quiet 30 seconds later.
After undergraduate neurology teaching had combed out much woolly thinking it became possible to appreciate clinical neurology at its pre CT scan peak. Saturday mornings spent, at a cost of 10 shillings each, at the National Hospital, Queen Square, were rewarded not only with masterly case demonstrations but also the opportunity to observe different personalities exhibiting, for example, a gleam of Irish wonder at a case of alexia without agraphia, military planning, precision and clarity, Gielgudian ability to recount the experience of others and, from the merest hints in the history, encourage the patient to divulge diagnostic clues, and humour appreciated both by patients and audience.
Apart from any other consideration, the discomfort and risk involved in neuroradiological investigation at that time demanded prior expert assessment. The advent of CT and subsequently MRI scanning inevitably appeared to reduce this need and at the same time exposed some limitations of clinical neurology. For a time it made sense to invest in greater scanning capacity than to increase the number of neurologists.
Whereas in the early 1960s Scientific American popularised knowledge of the structure of DNA and RNA, and reported the Davson-Danielli lipid bilayer model of the cell membrane, with putative pores, genomes have now been mapped and journals are littered with models of membrane proteins and ion channels, albeit often still reminiscent of Heath Robinson.
The corresponding explosion of neurological knowledge over the same period has inevitably led to an increasingly subtle appreciation of history and signs. Further leaps are likely as functional MRI scanning disentangles defects in parallel and interactive processing, perhaps contributing to an understanding of consciousness, and as the neurogenetic web becomes finer, perhaps eliminating some current difficulties in clinical identification of genotype from phenotype. Despite technological advance, it seems likely that professional pride and interest will continue to improve the clinical accuracy of the neurologist in eliciting and interpreting signs, not least to determine the significance of incidental findings and avoid unnecessary or inappropriate treatment. A much more rapid learning curve is demanded than in earlier decades and as a result there is a clear need to simplify reliable access to this knowledge and at the same time provide a comprehensive view of the subject.
In my opinion, Larner’s book on neurological signs and their meaning achieves this very well, albeit with occasional qualifications. A great wealth of information has been amassed and collated and often complex topics distilled with consistent clarity. While principally concerned with objective physical signs, subjective symptoms of special anatomical or pathological significance are included, each as a phenomenon of semiological significance. The retentive reader of this book should certainly be able to pursue the active process of seeking information from history and examination in a focused manner for signs that might otherwise be missed, whether more common complaints of urgency of micturition or Lhermitte’s phenomenon or rarities such as palinopsia or environmental tilt (though I missed the more common flying saucer syndrome of morning myoclonus).
In fact, despite the author’s comment that he cannot hope to be comprehensive given the diversity of neurological function, cover is remarkably extensive though concentration on more esoteric aspects has left rare gaps. Dropped head syndrome is included but not waddling gait or relative preservation of abdominal reflexes in familial spastic paraparesis. Several eponyms are attached to lid retraction but fear is not mentioned. Given the inclusion of De Musset’s sign of head tremor secondary to aortic valve regurgitation, the deliberate omission of ‘bruit’ (whether carotid, cranial or spinal) might perhaps be reversed in future editions. Primary dermatological conditions of neurological relevance are not included but itching, goose pimples, oedema, and cyanosis, of neurogenic origin, might be considered, together with pallor or facial flushing that may accompany migraine or migrainous neuralgia respectively, or partial seizures. Given the author’s thoroughness a further expansion to tap into the rich but stereotyped vocabulary describing sensory symptoms, sometimes with a suggestion of specific pathway involvement, would be of interest together with additional description of focal seizures, including not only ‘butterflies’ but perhaps the rare hallucination of focal or generalised elemental colour, green or purple being commonest in the reviewer’s experience, together with mention of the visual ‘blackout’ or ‘whiteout’ which may occur at the onset of syncope. The slow spread of the migrainous aura and the often precise 20 minute duration of migrainous visual hallucinations might be emphasised to contrast with the more rapid spread, if any, of focal epilepsy and its usually brief duration. Perhaps neurogenic breathlessness deserves mention, whether measured simply by counting out loud while exhaling one breath, and progressive impairment of gait with distance that may be associated with a spinal arteriovenous malformation or multiple sclerosis. A stamping gait may still be found. Given their increasing use, statins causing painful muscle swelling and dark urine of rhabdomyolysis might be added to causes of calf hypertrophy. Synkinesis might extend to include spread of movement on performing voluntary rapid horizontal tongue movements to involuntary associated movement of the lower jaw (and sometimes beyond) that may signal corticospinal disorder. Hydrophobia might be included to minimise temptation of an insular providence. A section for colloquial descriptions might be included, for example the ‘zig-zags’ or ‘tunnel vision’ of migrainous visual aura.
The book’s principal strength is its structured approach and the author’s skill in achieving a succinct definition of each sign, a brief account of the clinical technique required for it to be elicited, a description of other neurological signs that may accompany the index sign and, where known, a brief account of its basis in terms of neuro-anatomy, pathophysiology, pharmacology and neuropathology, together with a differential diagnosis of the commonest clinical diseases causing or associated and brief details of specific treatment, if available. A wide range of salient references is provided and expertly summarised, the entry under ‘vibration’ being a particular example. The author does not flinch from and indeed appears to revel in disorders of higher mental function. His comment that ‘with the passage of time, agnosic defects merge into anterograde amnesia (failure to learn new information)’, made this reviewer concentrate very hard. Intriguing entries include the association of slow relaxing reflexes with complete heart block and their normalisation after cardiac pacing, Fisher’s sign indicating the paucity of facial expression following a non-dominant hemisphere lesion, the synaesthesia of Scriabin, Messiaen and Nabokov, and alloaesthesia in which a sensory stimulus given to one side of the body is perceived at the corresponding area on the other side after a half-second delay, the reviewer observing this for the first time a week before reading this entry.
The author’s common sense approach is apparent under the entry ‘weakness’, stating that ‘testing records only the best forced maximal contraction and should not develop into an unseemly trial of strength between patient and examiner’. The existence of some degree of observer bias is acknowledged. Powers of tact and observation are mirrored by entries under ‘psychogenic tremor’ and ‘head turning sign’ (though in this context focal adversive seizures might be added to the description of seizure semiology).
Occasional entries may require some qualification or correction. The reviewer was disappointed not to find mention of anosmia under the Foster Kennedy syndrome. While it was Kennedy’s aim to emphasise the occurrence of ‘true retro bulbar neuritis with the formation of a central scotoma and primary optic atrophy on the side of the lesion, together with concomitant papilloedema in the opposite eye’, as the result of an ipselateral inferior frontal lobe tumour or abscess, impairment or loss of the sense of smell was acknowledged in each of his six cases.
While festinant gait is correctly identified as ‘hurrying’, it appears to mean ‘shuffling’ under another entry.
While the association of glove and stocking sensory loss with peripheral neuropathy is not challenged, examination may sometimes reveal evidence of a high cervical cord syndrome in patients with a similar story. On this note it is not clear that Van Gijn would agree that the first response of the hallux is necessarily the critical observation in eliciting an extensor plantar response.
The author, like Dr Johnson, is limited by the literature at his disposal. With regard to the Holmes–Adie or tonic pupil this is bedevilled by misquotation and misapprehension. Complete or almost complete loss of light reflex to the naked eye, with tonic constriction and dilatation on accommodation are cardinal features, together with cholinergic super-sensitivity and residual focal constriction to light on slit lamp examination. With time the tonic pupil may diminish in size, eventually becoming smaller than the opposite normal pupil. The literature is similarly confusing with regard to the Argyll Robertson pupil. Herpes zoster, Charcot–Marie–Tooth disease and Dejerine–Sottas hypertrophic neuropathy are more likely to be accompanied by a tonic pupillary abnormality. With regard to palatal myoclonus, a sense of disappointment was felt that the red nucleus appears to have lost its place in the Guillain Mollaret triangle, this being reduced to the dentato-olivary pathway. Entries regarding the definition of plegia and paresis seem to have been reversed in relation to ophthalmoplegia and ophthalmoparesis. Valuable explanations of signs (with references) are given in many cases, where these are known. The counterintuitive finding of a relative afferent pupillary defect with retrochiasmal lesions of the pupillary light reflex pathway is unexplained but it has been suggested that this may result from asymmetry of nasal and temporal fields. Given the mention elsewhere of bow tie nystagmus a future edition might include the bow tie optic atrophy that may occur in optic tract lesions. Reference to the distal optic nerve in the context of Traquair’s junctional scotoma seems odd but again appears to reflect usage in the literature. The tic of trigeminal neuralgia surely occurs in response to the sudden, dolorous, pain.
While the author’s reference to ring scotoma in retinitis pigmentosa is correct, in this reviewer’s experience tunnel vision has been more common while glaucoma and Vigabatrin induced peripheral field loss have been more frequent causes. While the enlargement of the blind spot seems invariable in papilloedema, with inferior nasal field constriction an occasional finding, a generalised constriction of peripheral field seems unusual other than in more severe cases.
Extensive and valuable lists featuring classification, causes and associations are given. Many eponyms are included but the emphasis invariably is on the sign named. Each entry needs to be read in its entirety, if possible with cross references. While often demanding of its readers this book will heighten the perception of all students of neurology approaching their patients.
The text contains a modest number of typographical errors, most commonly elisions, Murphy’s Law decreeing ironically that singultus should not be exempt. It seems likely that L5/S1 is intended rather than L1 as stated in relation to urinary retention due to acute cauda equina compression by prolapsed disc. The hypothetical neural integrator for horizontal eye movements is thought to lie in the nucleus prepositus hypoglossi.
Although a small number of disagreements or points of difference of emphasis have been identified this is clearly work of considerable scholarship and promise. It would have been counterproductive for the author to soldier on like Dr Johnson until most of his contemporaries were no more. Larner invites his readers to communicate any errors, disagreements or omissions. It is hoped that not only will they do so but that a collaborative effort will evolve that may in time provide an encyclopaedic approach akin to the OED, based upon historical principles aspired to by Dr Johnson, with corresponding supplements as the brain becomes increasingly conscious of its workings.
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