Neurology. Charles H. Clarke

Muscle wasting, a.k.a. amyotrophy Visible Absent Fasciculation Visible Absent Fibrillation Recordable on EMG, visible in tongue Absent Tone Flaccid/normal Increased/spastic type Weakness pattern Root, nerve or distal Pyramidal + dexterity Tendon reflexes Depressed/usually absent Exaggerated^a Clonus Absent Present Abdominal reflexes Present Absent Plantars Flexor (normal) Extensor

      ^a tendon reflexes can be absent/depressed initially with an acute UMN lesion.

      Sensory System

      Abnormalities are exceptional when the patient is articulate without sensory complaints.

      Focus neuro‐anatomically:

       Assess posterior columns first – vibration (VS) and joint position sense (JPS).

       Spinothalamic sensation: cold metal and a disposable sharp object.

       Light touch: fingertip or cotton wool. Avoid stroking/tickling.

       Two‐point discrimination (0.5 cm finger tips, 2 cm soles): useful & shows you are thorough.

       Chart sensory loss or altered sensation.

      Formulation

Drawing together data is essential. To conclude that a fall with loss of consciousness and residual weakness is ‘collapse?cause’ or a hemiparesis is ‘a CVA’ are not formulations any doctor should reach. Tease out the history and build on the signs found, to reach either a diagnosis or at least a direction for investigations. Such attention to detail can be hard in an emergency, but it is in acute neurology that many mistakes occur. For example, a sudden headache can be discounted when the reality is a subarachnoid haemorrhage, whereas thoughtful appraisal usually provides the correct answer. Another common error is the distinction between a seizure and syncope; epilepsy is overdiagnosed. It is sometimes taxing to formulate a diagnosis, but essential to try.

      Difficulties

      When a diagnosis is unclear, try to establish relevant and secure details – whether or not features are certain. A fact is a clearly witnessed account of a tonic–clonic seizure. Unequivocal signs are sustained ankle clonus and extensor plantars. Separate these from vague findings such as weakness, or dizziness without vertigo or nystagmus. Recognise, accept and record uncertainty – easier to write than to put into practice.

Diagnostic Tests

      We are surrounded by technology, by defensive practice and the need to provide reassurance by exclusion. Be aware of costs; try to target studies for some real purpose.

      Imaging

      This summary is a stepping‐stone to widely available resources, such as:

       htpps://radiopaedia.org

      Plain X‐rays have a limited role – skull, spine and skeleton – and radio‐opaque implants and ventricular shunts.

CT (computerised tomography) uses X‐rays to generate thin tomographic slices. CT relies upon tissues attenuating X‐rays to different degrees. Grey‐scale images are adjusted to provide optimal contrast between brain, water (CSF) and bone (Figures 4.1 and 4.2).

Figure 4.1 Axial brain CT: brain windows.

Figure 4.2 Axial brain CT: bone windows. White arrow: ossicles. Black arrow: cochlea. Arrowhead: mastoid bone trabeculations.

Figure 4.3 CT Myelogram. (a): Sagittal. (b): Axial. Intrathecal contrast creates high attenuation CSF, outlines vertebral canal contours, cord (white arrowhead) and nerve roots (white arrows).

Figure 4.4 Axial MR (a) T1w – CSF black. (b) T2w – CSF white, grey matter hyperintense to white matter.

CT myelography images the cord and nerve roots (Figure 4.3).

Magnetic resonance imaging (MRI) uses magnetic fields (1.5 Tesla and 3 Tesla) with radiofrequency pulses to generate signals from protons in water molecules. Two commonly used sequences (Figure 4.4) produce images based on variations in relaxation times of protons, generating T1‐weighted (T1w) and T2‐weighted (T2w) images.

Many other sequences are used – Fluid Attenuated Inversion Recovery (FLAIR), diffusion‐weighted imaging (DWI) and susceptibility‐weighted imaging (SWI). Gadolinium is used for contrast. CT and magnetic resonance angiography (MRA, Figure 4.5) are used for vascular imaging.

Figure 4.5 MR Angiography: contrast MRA of neck vessels.

      Advanced MRI, functional MRI, and MR spectroscopy are used in specialist units, and also positron emission tomography (PET) and single‐photon emission computed tomography (SPECT).

      Duplex ultrasound, a.k.a. Doppler, is commonly used to assess extracranial carotid arteries. Transcranial Doppler (TCD) gains information from intracranial vessels and has therapeutic possibilities.,

Digital subtraction catheter angiography (DSA) is the gold standard for vascular