Clinical Assessment of Muscle Tone, Meningeal Signs, and Motor Strength Testing

Types of Increased Muscle Tone (Hypertonia)

There are several types of increased muscle tone:

• Spasticity (Clasp-Knife Rigidity)

  Characterized by initial high resistance to passive movement, which then suddenly decreases (like opening a clasp knife). This is typical of **pyramidal tract lesions**.

• Plastic Rigidity (Lead-Pipe Stiffness)

  The increased muscle tone is constant and uniform throughout the entire range of passive movement. This is often found in **Parkinson's disease**.

• Cogwheel Rigidity

  Muscular resistance feels like small, successive jerks or jolts during passive movement, often described as if the joint were replaced by a sprocket. This can also be found in **Parkinson's disease**.

Meningeal Signs Examination

The presence of these signs suggests meningeal irritation:

1. Nuchal Rigidity (Stiff Neck)

   The patient should be supine, relaxed, and without a pillow. The examiner attempts to **flex** the head, noting any resistance. In meningeal irritation, resistance occurs during head flexion, but not usually during lateral movements. Caution: This maneuver should only be performed if there is no history of head or neck trauma, and the stability of the cervical spine is confirmed.

2. Brudzinski's Sign

   If the examiner passively **flexes** the patient's head (using slightly more energy, but without exaggeration), a positive sign occurs if there is involuntary flexion of the lower limbs at the hips and knees. This should not happen under normal conditions.

3. Kernig's Sign

   Two alternatives for testing:

   • Raise both legs straight and observe if they tend to **flex** at the hips and knees.
   • **Flex** the leg at the hip and knee, and then attempt to stretch (extend) it. Note any resistance or pain. Repeat with the other limb.

   When the phenomenon is bilateral, it suggests meningeal irritation. When unilateral, it may correspond to lumbosacral radiculopathy (lumbo-sciatica).

Assessment of Muscle Strength

Upper Limb Strength Testing

• Elbow Flexion (C5, C6): Biceps Brachii.
• Elbow Extension (C6, C7, C8): Triceps.
• Hand Grip/Prehension (C7, C8, T1): The patient squeezes the examiner's crossed index and middle fingers.
• Finger Abduction (C8, T1): Interossei muscles. Patient keeps hands palm down, fingers extended and separated, resisting external pressure attempting to push the fingers together.
• Thumb Opposition (C8, T1): Median Nerve. The patient moves the thumb toward the little finger against the examiner's resistance.

Lower Limb Strength Testing

• Hip Flexion (L2, L3, L4): Iliopsoas muscle.
• Hip Extension (S1): Gluteus Maximus.
• Hip Adduction (L2, L3, L4): Adductor muscles. The patient resists the examiner's attempt to separate the knees.
• Hip Abduction (L4, L5, S1): Gluteus Medius and Minimus. The patient separates the knees against resistance.
• Knee Flexion (L4, L5, S1, S2): Hamstrings.
• Knee Extension (L2, L3, L4): Quadriceps.
• Foot Dorsiflexion (L4, L5): Mainly Tibialis Anterior.
• Foot Plantar Flexion (S1): Mainly Gastrocnemius and Soleus.