Exame neurológico dos membros inferiores

Existem mais de uma maneira de realizar um exame neurológico e o clínico deve desenvolver sua própria técnica. Uma técnica inadequada não conseguirá detectar sinais ou produzirá resultados falsos.

See the separate História e Exame Neurológico article which covers the basic principles of examination and technique.

Inspection of the lower limbs¹

Note whether there is any damage to the feet. Neuropathic ulcers and neuropathic joints develop because of a lack of pain perception. Pain is a protective mechanism. When inspecting the motor system, the following points should be assessed:

• Note the resting posture. Establish whether there is unusual rotation or posture of a joint. Note whether the patient is symmetrical.

• Look for muscle wasting or hypertrophy: note whether it is focal or diffuse.

• Procure por movimentos involuntários, como tremores, tiques, espasmos mioclônicos, coreia ou atetose.

• Look for muscle fasciculation (a sign of lower motor neurone disease process). These are subcutaneous twitches over a muscle belly at rest. Tapping the belly may stimulate fasciculation.

Examination of the lower limbs may be performed more easily with the patient lying on a couch.

Exame de cada uma das modalidades sensoriais¹

Toque leve

• Use o toque suave de um dedo, um pedaço de algodão ou um pedaço de papel tissue.

• É importante tocar e não acariciar, pois uma sensação de movimento, como esfregar e coçar, é conduzida ao longo das vias de dor.

• Peça ao paciente que feche os olhos e diga quando sentir que você está tocando nele.

• Compare cada membro na mesma posição.

• Mantenha o tempo de cada toque irregular para evitar que o paciente antecipe.

• A logical progression is required. You may want to start testing over the groin and to move down the front of the leg and up the posterior side as this moves progressively from L1 to S3 dermatomes.

• Observe quaisquer áreas de hipoestesia ou disestesia.

Toque agudo (pontada)

• Teste usando uma agulha descartável dedicada. Uma agulha hipodérmica descartável é muito afiada.

• Use a área esternal para estabelecer uma referência de nitidez antes de começar.

• Follow the same progression as with light touch with the patient's eyes closed, comparing both lower limbs.

• Peça ao paciente para relatar hipoestesia (sensação de entorpecimento) ou hiperestesia (sensação de maior sensibilidade).

Temperatura

• Isso costuma ser negligenciado, mas pode ser importante.

• An easy and practical approach is to touch the patient with a tuning fork, as the metal feels cold.

• Compare a qualidade da sensação de temperatura nos braços, rosto, tronco, mãos, pernas e pés.

• Recipientes com água morna e fria podem ser usados para uma avaliação mais precisa. Peça ao paciente para distinguir entre quente e frio em diferentes áreas da pele com os olhos fechados.

Sensação de posição articular (própriocepção)

• Test at the interphalangeal joint of the big toe.

• Hold the proximal phalanx with one thumb and finger and hold the medial and lateral sides of the distal phalanx with the other. Move the distal phalanx up and down, showing the patient the movement first.

• Peça ao paciente para fechar os olhos e mover a falange distal para cima e para baixo aleatoriamente. Peça ao paciente para dizer a direção do movimento a cada vez.

• Test on both feet.

• If there is an abnormality, move backwards to the metatarsophalangeal joint and so on until joint position sense is normal.

Sensação de vibração

• Use um diapasão de 128 Hz e certifique-se de que o diapasão esteja vibrando.

• Coloque-o no esterno para começar, para que o paciente possa sentir a sensação.

• Then place it on the big toe.

• If no vibration is sensed, move backwards to the bony malleolus of the ankle, the tibial shaft and tuberosity and the anterior iliac crest.

• Pedir ao paciente que informe quando o diapasão parar de vibrar pode ser útil se houver dúvida de que a sensação de vibração esteja preservada.

2-point discrimination

• This test is not usually performed on the soles of the feet because the distinguishing distance is usually much greater than that on the fingers.

Interpretando os achados

The site of any lesion can be determined by looking at the pattern of any dysfunction found. The dermatomal (segmental) and peripheral nerve innervation is labelled below.

Exame Neurológico

© Häggström, Mikael (2014). "Galeria médica de Mikael Häggström 2014". WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.008. ISSN 2002-4436. Domínio Público

• All of the sensory modalities can be affected in peripheral neuropathies and nerve injuries, radiculopathy due to disc lesions and spinal injuries.

• Se um nervo ou raiz sensorial individual for afetado, todas as modalidades sensoriais podem ser reduzidas.

• If there is a spinal cord lesion, there may not be equal diminution across all of the sensory modalities: light touch, vibration and joint position sense may remain intact while sharp touch and temperature are lost. This is because the lateral spinothalamic pathways may be damaged while the dorsal columns remain intact.

• Problems with joint position sense or vibration usually occur distally first. Joint position sense is also required for balance, gait and co-ordination.

• A sensação de vibração pode ser perdida antes da sensação de posição articular na neuropatia periférica ou mielopatia que afeta as colunas dorsais.

• Vibration sense over the ankles is often diminished or lost in elderly people with no apparent neurological lesion.

• As partes distais dos membros tendem a ser afetadas na polineuropatia, geralmente as pernas antes dos braços. É produzido um efeito de 'luva e meia'.

Tônus

• Tone is the resistance felt when a joint is moved passively through its normal range of movement. Hypertonia is found in upper motor neurone lesions; hypotonia is found in lower motor neurone lesions and cerebellar disorders.

• Clonus is rhythmic and involuntary muscle contraction that can be provoked by stretching a group of muscles.

• Test tone:

  • Ask the patient to let their legs 'go floppy'.

  • Internally and externally rotate the 'floppy' leg. Assess for any increased or reduced tone.

  • Then lift the knee off the bed with one of your hands. Note whether the ankle raises off the bed as well, signifying increased tone.

• Test for ankle clonus:

  • Flex the patient's knee, resting the ankle on the bed.

  • Dorsiflex the foot quickly and keep the pressure applied.

  • You will be able to see the foot moving up and down if clonus is present.

Poder

• É necessária uma avaliação robusta de poder.

• O Conselho de Pesquisa Médica (MRC) possui um sistema de classificação recomendado para força (veja a tabela). Foi demonstrado que possui boa confiabilidade, embora tenham sido levantadas dúvidas sobre a ampla faixa do grau 4³ .

• O teste de força muscular manual é avaliado de forma diferente, sendo 4 - Bom: amplitude de movimento completa contra a gravidade com resistência moderada, e 5 - Normal: amplitude de movimento completa contra a gravidade com resistência máxima⁴ .

• Get the patient to contract the muscle group being tested and then you as the examiner try to overpower that group.

• Teste o seguinte:

  • Hip flexion, extension, adduction and abduction.

  • Knee flexion and extension.

  • Foot dorsiflexion, plantar flexion, eversion and inversion.

  • Toe plantar flexion and dorsiflexion.

Escala MRC para força muscular

Reflexos tendinosos profundos

• Certifique-se de que o paciente esteja confortável e relaxado, e que você possa ver o músculo sendo testado.

• Use um martelo de tendão para golpear o tendão do músculo e observar a contração muscular.

• Compare ambos os lados.

• Os reflexos podem ser hiperativos (+++), normais (++), lentos (+) ou ausentes (-). ± é usado quando o reflexo está presente apenas na reinicialização (veja abaixo).

• In the lower limbs:

  • Test the knee jerk (L3, L4): flex the patient's knee and support it by using one of your hands in their popliteal fossa. Elicit the reflex by tapping just below the patella.

  • Test the ankle jerk (S1): with the patient lying down, flex their knee and dorsiflex their ankle, at the same time rotating their leg slightly laterally. Elicit the reflex by tapping over the Achilles tendon just above the heel. If this is difficult to elicit, an alternative method is to ask the patient to kneel on a chair, facing the back of the chair, so that their feet are dangling off the seat of the chair. Tap over the same area in this position.

• If a reflex is difficult to elicit, try 'reinforcement' (the Jendrassik manoeuvre). Ask the patient to flex their fingers and interlock them with one palm facing upwards and the other facing downwards. Then ask them to try to pull their fingers apart just before you strike the tendon.

Interpretação

• Lesões do neurônio motor superior geralmente causam hiperreflexia.

• Lesões do neurônio motor inferior geralmente produzem uma resposta reduzida ou ausente.

• It may be normal to have reduced or absent ankle reflexes in some elderly people, although the frequency and significance of this is disputed.

• Isolated loss of a reflex can point to a radiculopathy affecting that segment - eg, loss of ankle jerk if there is an S1 disc prolapse.

Superficial tendon reflexes

• In the lower limbs, this is the plantar response.

• To elicit this, the patient should be lying down with their legs extended.

• Use a blunted point and run this along the lateral border of the foot, starting at the heel and moving towards the big toe.

• Stop on the first movement of the big toe.

• An extensor plantar response (upgoing big toe) is pathological and signifies an upper motor neurone lesion.

Exame de coordenação

• The cerebellum helps in the co-ordination of voluntary, automatic and reflex movement. Tests of cerebellar function in the lower limbs require normal power, tone and sensation to be valid and include:

• The heel-shin test:

  • Ask the patient to lift one of their legs and flex it at the knee, keeping the other leg straight.

  • They should then place the heel of the flexed leg on the knee of the other leg and run it down the shin towards the ankle and back again towards the knee.

  • Ask them to repeat this a number of times.

• The heel-toe test:

  • This tests balance mechanisms that rely on the cerebellar, vestibular and proprioceptive systems.

  • The patient either needs to be barefoot or wearing flat shoes.

  • They should walk in a straight line so that the heel of the second foot touches the toes of the first foot. This should be repeated so that the heel of the first foot then touches the toes of the second foot, etc, each time with the patient moving forward.

  • Look at how well they are able to perform this. Is there any staggering which would suggest a lesion of the cerebellum?

• Romberg's test:

  • This also tests balance mechanisms that rely on the cerebellar, vestibular and proprioceptive systems.

  • Ask the patient to keep their eyes open and stand with their feet together, arms by their sides.

  • Then ask them to maintain this position when they close their eyes.

  • Patients who have cerebellar lesions often cannot stand in this position, even with their eyes open. If balance is only lost when the eyes are closed, this signifies a proprioceptive or vestibular lesion.

  • Be ready to catch the patient by standing behind.

• No neurological examination, especially of the lower limbs, is complete without observing gait.

• This is an enormous topic and there are separate articles discussing Marcha Anormal e Anormalidades na Marcha em Crianças.

• Also, watch the patient as they rise from the chair to walk and note any abnormality of movement.