Diseño de la Base de Datos

History

A 35-year-old man has presented with a severe burn to his right hand. He tipped some boiling water on to the hand a few hours earlier, which led to severe erythema and blisters, but he does not complain of any pain from the injury. Over the last month he has experienced mild shoulder pain, exacerbated by coughing, and bilateral leg stiffness resulting in walking difficulty. He works as a librarian. He has no medical, drug, travel or smoking histories. He drinks fewer than 10 units of alcohol per week.

Examination

Cardiorespiratory and abdominal examinations are unremarkable. There is no rash or lymphadenopathy. Cranial nerve examination is normal, and no spinal tenderness is elic-ited. In the upper limb, tone is normal. His hands appear to have slight wasting bilater-ally, with mild weakness, but other myotomes are within normal limits. There is no wrist tenderness. Reflexes in the arms are absent. Light touch sensation is intact throughout the upper limbs, but pain sensation is absent bilaterally from C4 to T4 distribution. In the lower limbs, the tone is elevated with ankle clonus bilaterally. Power is globally reduced to 4/5 (Medical Research Council scale), and there is hyper-reflexia. All sensation modali-ties are intact in the lower limbs. Coordination and vibration sense are preserved in all limbs. Anal tone and perineal sensation are intact. A chest X-ray shows no abnormalities.

Observations: temperature 36.5°C, heart rate 80/min, blood pressure 105/70 mmHg, SaO₂ 100 per cent on room air.

INVESTIGATIONS

Normal range

White cells 6.0 4–11 ¥ 10⁹/L

Neutrophils 2.8 2–7 ¥ 10⁹/L

Haemoglobin 13.0 13–18 g/dL

Platelets 250 150–400 ¥ 10⁹/L

Sodium 137 135–145 mmol/L

Potassium 4.5 3.5–5.0 mmol/L

Urea 4.6 3.0–7.0 mmol/L

Creatinine 73 60–110 mmol/L

C-reactive protein 300 <5 mg/L

Bilirubin 20 5–25 mmol/L

Alanine transaminase 35 8–55 IU/L Alkaline phosphatase 180 42–98 IU/L

Albumin 35 35–50 g/L

Creatine kinase 88 60–320 IU/L

Erythrocyte sedimentation rate <10 Males, age/2;

females, [age+10]/2 Antinuclear antibodies Negative

Antinuclear cytoplasmic antibodies Negative

Questions

• What is the differential diagnosis?

• What should be the management plan?

In approaching a neurological case, it is important to try to localize where the lesion(s) are within the neurological system. When investigating weakness it can be divided into:

• myopathy (i.e. not a neurological disorder);

• neuromuscular junction disorder;

• peripheral nerve;

• radiculopathy/spinal cord lesion/myelopathy;

• lesion in the brainstem and/or cerebellum;

• cortical lesion.

The patterns of presentation differ and this helps to localize the lesion.

This patient’s neurological findings can be summarized as:

• spastic paraparesis in the lower limbs (as demonstrated by bilateral upper motor neu-ron signs);

• dissociated sensory loss in the upper limbs (i.e. spinothalamic impairment but intact posterior column);

• absent upper-limb reflexes with hand-muscle wasting.

Putting all this together suggests the lesion is within the spinal cord at the level of the cervical and upper thoracic cord. This will produce a segmental effect, as demonstrated by lower motor neuron signs in the upper limbs and long-tract effect, as demonstrated by upper motor neuron signs below the level of the spinal cord lesion.

Having established the site of lesion within the neurological system, the next step is to find out what type of cord lesion this is. The common causes of cord lesions are tumours, infection, disc disease and spondylosis, haematoma or cystic lesions. Except for disc dis-ease and spondylosis, most of these pathological processes can occur in the extradural, intradural or intramedullary space. All lesions within the spinal cord can produce local segmental damage and long-tract effects (i.e. damage/interruption to ascending and descending tracts within the cord).

With regard to local segmental damage, the lesions can affect (i) a nerve root (radiculo-pathy), which leads to severe, sharp, shooting, burning pain at that nerve root distribu-tion and is aggravated by movement, straining and coughing; or (ii) cord (myelopathy), leading to dull ache which is continuous, unaffected by movement and may radiate into the whole leg or even one half of the body. Bone pathology tends to cause localized ten-derness which is reproducible by palpation of the affected area. For long-tract effects, the effects are dependent on which long tract is affected (spinothalamic, posterior column, spinocerebellar or corticospinal tracts). In addition, damage to the sympathetic outflow at level of T1 or the cervical cord may lead to Horner’s syndrome. Bladder symptoms occur when both sides of the spinal cord are affected; usually they start with difficulty in initiating micturition before retention symptoms develop.

The combinations of presenting symptoms are also reflective of segmental damage within the affected cord. Cord lesion can be divided into (i) extrinsic compressive lesions, (ii) central cord lesions, (iii) cauda equina lesions. For extrinsic compressive lesions, the long-tract effects depend on the location of the tumour. For example, a posterior tumour causes ipsilateral posterior column lesions first (light touch, proprioception and vibration sensory loss) and, as it expands, it may cause further direct pressure effects or ischae-mia to the neighbouring tracts – so it may cause ipsilateral corticospinal tract lesions

179 (upper motor neuron signs) and then contralateral spinothalamic tract lesions (pain and temperature loss). If half of the spinal cord is affected then it produces a combination of symptoms consistent with Brown–Séquard syndrome.

In contrast with extrinsic compressive lesions, the central cord lesions produce a different set of long-tract signs. The centrality of the lesion means that the medially situated fibres are involved first. As the spinothalamic tract decussates at the level of the spinal cord, central cord lesions cause bilateral sensory loss at the level of the lesion initially. With a cervical central cord lesion the pattern of spinothalamic damage may expand to a ‘cape’

or ‘suspended’ pattern (with pain and temperature sensory deficit spared in the sacral distribution even with large central lesion) due to the peripheral location of sacral fibres within the spinothalamic tract. As the central cord lesion expands, corticospinal tracts are involved leading to lower motor neuron lesions at the level of spinal cord affected (e.g. hand-muscle wasting) and upper motor neuron signs below the level of lesions (e.g.

spastic paraparesis). Posterior column signs appear late.

Cauda equina lesions typically affect the lumbosacral areas. If lesions are affecting the sacral nerve roots they cause saddle anaesthesia and bladder symptoms earlier than other lesions.

This man’s symptoms and signs are consistent with a central spinal cord lesion. The combination of dissociated sensory loss and spastic paraparesis is highly suggestive of a cystic lesion known as syringomyelia. Other differential diagnoses are cystic intramedul-lary tumours, infection and haematoma. Subacute combined degeneration of the cord and multiple sclerosis can sometimes produce a similar collection of symptoms.

Syringomyelia is a rare disorder with a prevalence of 8.4 cases per 100 000 population.

An abnormal cerebrospinal fluid-filled cavity known as a syrinx develops in the spinal cord. If a syrinx develops within the brainstem, the condition is termed syringobulbia.

Syringomyelia is associated with Arnold–Chiari malformation which is a developmental abnormality of the brainstem and cerebellum: the cerebellar tonsils herniate through the foramen magnum. The pathophysiology of syringomyelia is incompletely understood.

Magnetic resonance imaging of the brain and spinal cord is the investigation of choice (Fig. 70.1), which will demonstrate the characteristic syrinx, the extent of the lesion and rule out other conditions as mentioned above. Cerebrospinal fluid (CSF) sampling is relatively contraindicated owing to the risk of herniation. The natural history of this condition is variable and neurosurgery is considered but is not curative because, despite best effort, at least 33 per cent of patients suffer progressive deterioration.

KEY POINT

• It is important to recognize the different patterns of neurological presentation in order to make an accurate neurological diagnosis.

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