Neurology. Charles H. Clarke

       Drift with pronation/descent towards midline is a cardinal sign of an early pyramidal lesion.

       Postural tremor, chorea, pseudochorea and asterixis become apparent. Rest tremor diminishes.

       Apply gentle downward wrist pressure and release: rebound – a cerebellar lesion.

       Fatiguability: inability to maintain the arm outstretched.

       Inspect arms, hands, nails.

       Non‐organic problems: often aimlessly waving around.

       Tone

      Distinguish between akinetic‐rigidity and spasticity.

      Extrapyramidal lead pipe rigidity is detectable throughout all passive movements. Take the hand through slow, extension, flexion, rotation movements. This elicits early stiffness in wrist and forearm muscles and cogwheeling. Stiffness becomes more evident when the opposite limb is moved actively a.k.a. synkinesis. By contrast, in spasticity, the early pronator catch or beats of ankle clonus will only become apparent if sought by brisk movements – quickly supinating the forearm or dorsiflexing the ankle: slow movements can miss these signs. A catch of increased tone at an ankle precedes sustained clonus.

       Power, Muscle Bulk, Consistency

      MRC 0–5 Power Grades:

       5: Normal

       4: 4+, 4− Active movement against gravity and resistance

       3: Active movement against gravity

       2: Active movement, gravity eliminated

       1: Flicker of contraction

       0: No visible muscle contraction.

      Limitations: inability to record slight weakness & dependence on cooperation. ‘I could just overcome hip flexion’ is better than 4⁺ and 4⁻. ‘Give‐way’ weakness means poor effort and/or pain. Assess skilled hand & foot movement: ‘play piano, wriggle toes’.

      Assess fatiguability, if needed. Consider focal or general muscle wasting, fasciculation, muscle bulk/consistency, myotonia.

       Cerebellar Signs

      Look for dysmetria (past pointing) and action tremor.

      Dysmetria: place the patient’s forefinger on the point of your tendon hammer shaft, at the limit of their reach; ‘now, please touch the tip of your nose, and back’. Move the shaft to a different position. Do not test finger–nose–finger rapidly – this misses early dysmetria. Follow with other tests – try circular polishing of the dorsum of the opposite hand with a single finger, and alternating forearm pronation/supination.

In the lower limb heel–shin test:

       Raise one leg, touch your opposite ankle with your heel and then move the heel up your shin, to the knee and down again.

       Repeat the sequence. Simply gliding one heel up and down the shin can miss early ataxia.

      Foot tapping also elicits incoordination.

      Knee jerks with a pendular pattern ‐ slow and swinging ‐ or absent reflexes do occur with cerebellar disease, if seldom.

      Dysarthria is usually obvious.

      Nystagmus rarely occurs without other cerebellar features.

      Remember: a midline cerebellar lesion may cause gait and trunk ataxia without limb ataxia.

       Tendon Reflexes

      Ensure the patient is relaxed – with head and trunk supported. Minor asymmetry is common, and reduced knee jerks compared with ankle jerks. Reinforcement: ask the patient to clench their teeth and then relax. Original Jendrassik manoeuvre: hook fingers together and pull.

      Do not miss slow relaxing reflexes: hypothyroidism.

       Absent Reflex→Clonus nomenclature

0	Absent with reinforcement	Almost always pathological
±	Present with reinforcement	Sometimes normal; may be pathological
+	Present	Normal
++	Brisk	Normal
+++	Very brisk	Pathological if tone increased; can be normal
CL	Clonus	>3 beats of ankle clonus = pathological; 2 beats may be normal

       Spinal levels of tendon reflexes, a.k.a. deep tendon reflexes – DTRs in US

C5–6	Supinator
C5–6	Biceps
C7	Triceps
C8	Finger jerks
L(3)4	Knee
S1	Ankle

       Extensor Plantar (Babinski)

      Babinski published the 26‐line phénomène des orteils (toes) in 1896. An extensor is an indication of a brain or cord UMN lesion. A reproducible upgoing toe by any reasonable stroking action on the foot is abnormal. Extensors are exceptional in normal adults.

       Superficial Abdominal Reflexes

Elicit muscle twitches by gentle stroking each quadrant with an orange‐stick – not with a needle. Superficial abdominals are lost with pyramidal lesions and hard to elicit or absent in the obese. Preservation of upper superficial abdominal reflexes with absent lower abdominals can occur with a thoracic sensory level in cord compression (T10 = umbilicus).

       Respiration, Diaphragm

      Respiration and the diaphragm can be assessed by observing inspiration and expiration and abdominal muscles. Selective diaphragm weakness causes paradoxical upward movement of the umbilicus – well seen with the patient supine during sniffing. Measure vital capacity.

       Lower and Upper Motor Neurone Lesions

See Table 4.2.

Table 4.2 Lower (LMN) & upper motor neurone (UMN) lesions.

Feature

LMN

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