Neurology. Charles H. Clarke

      Cerebellar Syndromes

      Features of cerebellar disease are well defined. With a lateral cerebellar lobe lesion, there is rebound and dysmetria in the ipsilateral limbs, dysarthria and nystagmus. With a vermis lesion, there is ataxia of stance, trunk & gait, sometimes with negative Romberg.

There are two practical points:

      First, if an expanding cerebellar mass lesion is suspected or found on imaging, there must be speedy liaison with a neurosurgeon. While all brain mass lesions are potentially serious, many tumours above the tentorium can be dealt with in an expectant manner. With a cerebellar mass progression can take place over hours or less. Secondly, to misdiagnose as non‐organic the ataxia of stance and gait of a midline lesion does happen. See cerebellar syndromes: (Chapter 17).

      Movement Disorders

      These can be divided into akinetic‐rigid syndromes, where poverty of movement predominates, and dyskinesias in which excessive movement is the principal feature. Akinetic‐rigid syndromes include idiopathic Parkinson’s, Parkinson‐plus, drug‐induced & post‐encephalitic parkinsonism, manganism (v.rare), childhood akinetic‐rigid syndromes and Wilson’s disease.

      Dyskinesias include tremors, chorea, hemiballismus, myoclonus, tics, dystonias, paroxysmal and drug‐induced dyskinesias. The distinction between the two groups is artificial. For example, Parkinson’s can be primarily tremulous; Wilson’s disease can have features of akinesia with an unusual tremor.

      No amount of writing surpasses seeing a movement disorder, either in the flesh or on video. See: Chapter 7.

      Diagnostic difficulties occur. First, when akinetic‐rigidity becomes apparent, early idiopathic Parkinson’s disease tends to be over‐diagnosed. The reality, evident some years later, is another akinetic‐rigid syndrome. Parkinson’s is almost always asymmetrical, and also should be diagnosed with caution if rest tremor is not apparent. Progressive supranuclear palsy (PSP) or multiple system atrophy (MSA) tend to be symmetrical from the onset. Consider Wilson’s disease in akinetic‐rigidity, or dyskinesia below 40.

      Benign essential tremor (BET), though common, can cause difficulty. Usually, tremor occurs when the limbs adopt a particular posture. However, forms of BET mimic benign tremulous Parkinson’s disease, and even cerebellar action tremor.

      Early chorea is easy to miss – mistaken for fidgeting. Minor dystonia can also escape recognition. Non‐organic movement disorders are difficult; many labelled initially as functional have organic disease.

      Paraparesis

      Spastic paraparesis, meaning lower limb weakness of cord or, rarely, cortical origin, is a pivotal diagnosis. Prior to MRI, clinical examination had a major role in differentiating between cord compression and other causes of paraparesis.

      The clinical picture begins with subtle features:

       Scuffing the toes of shoes, often worse on one side

       Stiffening of gait (spastic gait) with retention of a narrow base

       Noticeable beats of ankle clonus (e.g. on a step or kerbstone)

       Changes in lower limb sensation.

Spinal pain is common in cord compression. With a thoracic meningioma, pain at tumour level develops with an emerging spastic paraparesis and a sensory level, rising from below. The patient complains of numbness or altered sensation commencing in the feet, that marches upwards, over days, weeks or longer. Brown‐Séquard features (pyramidal signs on one side, spinothalamic on the other) may appear.

      These features apply equally to tetraparesis (syn. quadriparesis).

      The five principal features of a pyramidal lesion may not all be present. Pain may not be present in cord compression. Marked asymmetry can sometimes cause difficulty.

      Two questions arise when signs of spastic paraparesis are found:

       Is the paraparesis caused by cord compression?

       Is the paraparesis the result of a condition in which it is part of the picture? Examples are:MSMNDSubacute combined degeneration of the cordSyringomyeliaCortical lesions such as a parasagittal meningioma, hydrocephalus and other brain lesions can occasionally cause paraparesis.

      Paraparesis is also caused by many rarities, such as vascular anomalies of the cord, adrenoleucodystrophy and copper deficiency (see Chapter 16). There can be difficulties with the initial diagnosis: within primary care, especially when restricted to a brief telephone call, emergence of difficulty in difficulty in walking is not taken seriously, and early features of a paraparesis can pass unrecognised.

      Brainstem Syndromes

Anatomy is outlined in Chapter 2. Figure 4.9 is a helpful diagram, repeated here in a clinical context: think of the level within the brainstem and of the dorso‐ventral plane. The usual hallmark is coexistence of damage to motor and/or sensory fibres and to cranial nerve nuclei. Syndromes involving oculomotor nerves III, IV and VI indicate upper or mid brainstem disease. Mid and lower brainstem disease affects nuclei VII–XII.

Bulbar and pseudobulbar palsy describe common brainstem syndromes (Chapter 13). Both cause dysarthria, dysphagia, drooling and respiratory problems. Bulbar palsy means disease of the lower cranial nerves (IX, X, XII), their nuclei and muscles. Pseudobulbar palsy is shorthand for UMN lesions of lower cranial nerve nuclei. MS, brainstem stroke and MND cause pseudobulbar palsy, the latter usually both pseudobulbar and bulbar. Advanced Parkinson’s causes poverty of movement of these muscles.

Figure 4.9 Brainstem: lateral schematic view.

      Source: Hopkins (1993).

      Anterior Horn Cell Disease

      Relatively few diseases afflict the anterior horn. All are serious. The commonest is MND; spinal muscular atrophies, Kennedy’s disease, poliomyelitis and other viruses, notably West Nile are also causes. LMN signs of wasting and weakness develop. Amyotrophy is also a word used to describe wasting; it means myo (muscle) atrophy. Typically in all these diseases, initially at least, weakness can be highly selective. For instance, MND can present with weakness of one or two finger extensors. Neurophysiology is often diagnostic.

      Sensory Abnormalities: Patterns at Different Levels

      Sensation is difficult to evaluate. Eponyms abound – positive Tinel (carpal tunnel), tic douloureux, causalgia, anaesthesia dolorosa, lightning pains, Lhermitte, Brown‐Séquard, dissociated sensory loss, suspended sensory loss, sacral sparing, thalamic pain and astereognosis.

      An approach that some find valuable is that if a sensory symptom is the principal complaint, such as the pain of trigeminal neuralgia (Chapter 13) or nocturnal tingling of the hands in median nerve entrapment at the wrist (Chapter 10), the quality of symptoms tend to be diagnostic. In other situations, the history and neurological signs suggest