Understanding Neurology

224The ulnar nerve is most prone to injury where itpasses across the medial epicondyle at the elbow (the‘funny bone’). Elbow fractures or repeated chronictrauma (e.g. leaning on the elbows) can cause ulnardistribution sensory symptoms and loss, progressingto ulnar weakness. Compressing the ulnar nerve atthe medial epicondyle may reproduce thesesymptoms. Radial nerve lesions rarely present assensory syndromes.SUMMARY❏❏Numbness and tingling may arise from lesionsdirectly affecting the neuraxis, from the level ofthe peripheral nerve and sensory receptor throughthe spinal cord to cortical level: these symptomsmay be secondary to non-neurological disorders.Distinct patterns of sensory loss and associatedfeatures facilitate clinical localization of thelesions: an understanding of the basicneuroanatomical pathways subserving sensationand their physiology enables this.CLINICAL SCENARIOS❏❏❏❏Separation of sensation into large fibre/posteriorcolumn function versus small fibre/ spinothalamicfunction helps in considering peripheralnerve and spinal lesions; assessment ofproprioception and pain are useful screeningexaminations.Cortical and subcortical lesions produce loss ofintegrated sensory functions but these functionsdepend on intact spinal and peripheral sensorypathways: gross sensation may be intact withthese higher level lesions.Sensory symptoms must not be considered inisolation: enquiry regarding motor andautonomic symptoms should be made whereappropriate, and a full neurological examinationshould be conducted.An accurate sensory assessment may avoidunnecessary investigation.CASE 1A 60-year-old, right-handed female presented tothe neurology clinic with a 6-month history ofascending paraesthesiae, affecting her feetinitially, but then progressing to a level below theknees. These symptoms were most noticeable inbed at night. She had also become aware of beingslightly unsteady, especially in the dark. Shedenied any weakness, upper limb symptoms, orbladder symptoms. Past medical history wasunremarkable, and she was not taking anyregular medications. She was a nonsmoker, anddrank