Clinical Examination of a Patient with Possible Neuropathic Pain Maija Haanpää, MD, PhD18 Helsinki University Hospital, Department of Neurosurgery, Helsinki, Finland; Etera Mutual Pension Insurance Company, Helsinki, Finland Educational Objectives Th is chapter explains the crucial role and prac- tical performance of the bedside examination of a pain 1. State the defi nition of neuropathic pain and de- patient with suspected neuropathic pain. Despite the scribe grading methods to determine clinical cer- development of neurophysiological and neuroimaging tainty of neuropathic pain. methods, taking a history and performing a clinical ex- 2. Give an overview of the clinical examination for di- amination of a patient, using simple tools, remain the agnosing neuropathic pain. most important step in the diagnostic process. Basic knowledge of neuroanatomy, suffi cient practical train- 3. Discuss the limitations and challenges of clinical ing in neurological examination, and an analytic ap- examination in diagnosing neuropathic pain and in proach in the patient are needed. Th e accompanying diff erentiating it from other types of pain. chapters by Truini and Meier review laboratory tools, quantitative sensory testing, and confocal corneal mi- Th e Rationale for Diagnosing croscopy in assessing patients with possible neuropath- Neuropathic Pain ic pain. Neuropathic pain causes suff ering and disability for Defi nition of Neuropathic Pain many patients and is a well-known public health prob- lem. Neuropathic pain diff ers from nociceptive pain IASP defi nes neuropathic pain as “pain caused by a le- in terms of symptoms, mechanisms, and therapeutic sion or disease of the somatosensory system.” Com- management [2]. Early diagnosis is a prerequisite for pared to the former defi nition, “pain initiated or caused adequate management. Hence, the basics of clinical ex- by a primary lesion or dysfunction of the nervous sys- amination of a patient with suspected neuropathic pain tem,” the current defi nition is more restrictive and pre- should be familiar to all clinicians treating pain patients. cise by necessitating “a lesion or disease” instead of In specialized pain centers, more extensive skills should the obscure “dysfunction” and by locating it in the “so- be available for diagnosing pain conditions, including matosensory system” instead of the broader “nervous skilled clinical examination and the availability of labo- system.” For example, the new defi nition excludes pain ratory examinations needed to confi rm or exclude sus- secondary to increased muscle tone in pyramidal or ex- pected cause of the pain state. trapyramidal motor system diseases from neuropathic Pain 2014: Refresher Courses, 15th World Congress on Pain Srinivasa N. Raja and Claudia L. Sommer, editors 201 IASP Press, Washington, D.C. © 2014 202 Maija Haanpää pain [9,14]. Th e lack of structural abnormalities in pain (non-painful visceral percepts). Descending tracts are states such as fi bromyalgia or complex regional pain also part of the somatosensory system. Th ese tracts syndrome, type I, currently excludes them from neuro- originate in cortical, subcortical, and brainstem regions, pathic pain, although there may be subgroups in these importantly including the midbrain periaqueductal diagnostic categories that fulfi ll the requirement of a gray and rostroventral medial medulla. Th e projections recognized lesion in the nervous system [20]. With ad- from the brainstem are both inhibitory and facilitatory. vances in neuroscience, new conditions are now includ- Th e variable nature of neuropathic pain is not surpris- ed in the concept of neuropathic pain, such as primary ing, considering the complexity of the somatosensory erythromelalgia, a painful condition caused by a muta- system and the myriad of ways it may be aff ected by tion in the SCCN9A gene that codes for the voltage-gat- disease or injury. Th e literature on neuropathic pain ed sodium channel NaV1.7 [6]. overemphasizes conscious perception of sensory in- Neuropathic pain is a syndrome caused by formation from the skin. However, we lack standard- a range of diff erent diseases or lesions. Neuropathic ized methodology for the assessment of pain from deep pain can arise from damage to the nerve pathways at tissues (such as muscles and joints) and from viscera, any point from the terminals of the peripheral noci- which are the more dominant areas of complaint from ceptors to the cortical neurons in the brain. It is not patients. [11] known why the same condition is painful in some pa- tients and painless in others. Neuropathic pain is clas- Aims and General Principles sifi ed as central (originating from damage to the brain of Assessment of a Pain Patient or spinal cord) or peripheral (originating from damage to a peripheral nerve, plexus, dorsal root ganglion, or Assessment of a patient with possible neuropathic root). Of note, the term “central pain” should never be pain aims at (1) recognizing what type of pain the pa- used to describe chronifi cation of an acute pain (de- tient has—nociceptive pain, neuropathic pain, a com- spite producing central changes), as it is reserved for bination of them (called “mixed pain”) [2], or neither neuropathic pain associated with lesion(s) in the cen- of them; (2) diagnosing the disease(s) or event(s) that tral nervous system. caused the pain; and (3) recognizing the functional limitations, possible comorbidities, and other impor- Neuroanatomy of Neuropathic Pain tant aspects related to tailoring the management of the patient. Th e best clinical tools in pain assessment Th e somatosensory system comprises mechanorecep- are the clinician’s capacity to listen to patients as they tion, thermoreception, nociception, proprioception, tell their story, careful observation, and thorough and visceroception functions, providing conscious physical examination. perception of sensory information from the skin, the Medical history. It is best to initiate the med- musculoskeletal system, and the viscera [5]. Th e so- ical history by permitting patients to fully describe matosensory system can be divided into the dorsal their pain experience as they understand it. Th e his- column-lemniscal system and the spinothalamic tract tory should include questions about the location, in- system. Th e former subserves mechanoreception and tensity, character, temporal profi le, and possible exac- proprioception, and the latter thermoreception, noci- erbating factors of the pain. Concomitant symptoms ception, and visceroception. Th e two systems project should also be queried. Past medical and surgical his- via the ventrobasal and intralaminar groups of tha- tory, psychosocial history, and functional history (i.e., lamic nuclei into a network of somatosensory cortex the impact of symptoms on level of mobility, activities areas, which include the primary and secondary so- of daily living, relation with others, sleep, and mood) matosensory cortex, posterior parietal cortex, pos- are also important. terior and mid-insula, and mid-cingulate cortex. Be- Conscious observation of patients from the sides these two main systems, other pathways have very fi rst moment of the appointment—their way of been suggested to be involved in mediating somato- expressing themselves, cognition, movement, gait, and sensory functions, such as the dorsal spinocerebellar general behavior—is important in giving the physician tract (lower limb proprioception), postsynaptic dorsal a general impression and clues about any functional column pathway (pelvic organ pain), and vagus nerve impairment they may have. During the history the Clinical Examination of a Patient with Possible Neuropathic Pain 203 physician formulates hypotheses about the type of pain the nociceptive submodality. In addition, allodynia to the patient has and the possible causes of pain. light moving tactile stimuli (dynamic mechanical al- Physical examination then tests these hy- lodynia), gentle pressure (static mechanical allodynia), potheses and hence verifi es or rejects the suggested innocuous warmth (heat allodynia), or cold (cold allo- explanations for the pain. In neurological examination dynia) may occur. It is helpful to document the extent the fi ndings should be consistent when tested multiple of each abnormal sensory fi nding on a body template. times in multiple ways, and they should be consistent Depending on the patient’s symptoms, specifi c with the pre-examination observation of behavior. If tests such as straight leg testing or Tinel’s test are per- there is any discrepancy between the patient’s perfor- formed. Guidelines and review articles are recommend- mance during the history and clinical examination, test- ed for specifi c clinical entities such as low back pain ing needs to be repeated or modulated so that the clini- [15,16], facial pain [21,25], or peripheral neuropathy [7]. cian can titrate out the real impairment from possible functional variation due to malingering or conversion Character of Neuropathic Pain syndrome. In addition to general examination, the pain Neuropathic pain is characterized by spontaneous and area is inspected and palpated. Next, neurological ex- provoked pain and negative signs (sensory defi cits) re- amination is performed to an adequate extent. Assess- fl ecting neural damage. Many patients with neural ment of cranial nerves, motor function, deep tendon damage only have negative symptoms, but some pa- refl exes, muscle tone, coordination, gait, and balance tients also have positive symptoms such as paresthesias is performed in