Ultrasound-guided spinal anesthesia in a patient with osteogenesis imperfecta

INTRODUCTION

Osteogenesis imperfecta (OI), also known as brittle bone disease, is a rare genetic disorder of type I collagen with multiple causative gene variants, leading to multiple phenotypic subtypes, associated with bone fragility, fractures, and connective tissue abnormalities. OI results in anatomic and physiological abnormalities, which makes any form of anesthesia a challenging task involving a careful multidisciplinary approach.

We report on a case of anesthetic management of a known case of OI who underwent a TENS (Titanium elastic nail) nail removal of the femur.

CASE REPORT

A 31-year-old male presented in the preanesthetic checkup clinic for TENS (Titanium elastic nail) nail removal of the right femur [Figure 1a]. He was a known case of osteogenesis imperfecta (OI) and had a history of fracture of the right femur shaft 2 years back, for which he had been operated on under spinal anesthesia with technical difficulty. There was no history of OI in the family.

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Figure 1:

(a) X-ray AP view right femur with TENS nail, (b) Chest X-ray AP view: Visible significant scoliosis of spine towards left, (c) 31 year old male patient with OI, (d) Palpation of spine (e) Position of the patient and USG transducer probe during paramedian sagittal scan of the lumbar paravertebral region, (f) Sagittal sonogram of lumbar paravertebral region, (g) Subarachnoid block given in the space L3-L4. TENS: Titanium elastic nail; AP view: Anteroposterior view OI: Osteogenesis imperfecta.

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On general examination, he was short-statured with a height of 100 cm, weighing 55 kg with fragile bones, progressive hearing loss, and kyphoscoliosis.¹ His blood pressure was 140/90 mmHg, and his heart rate was 114 beats/min. He was known to be hypertensive for 3 years on Tab Telmisartan 40 mg OD. There was no pallor, icterus, cyanosis, clubbing, lymphadenopathy, or pedal edema. The respiratory system revealed a barrel-shaped chest with bilateral equal air entry, and the cardiovascular system revealed normal heart sounds. Electrocardiogram (ECG), liver function test, renal function test, and coagulation profile were normal. Chest X-ray revealed mediastinal widening; X-ray of the spine revealed dorsolumbar kyphoscoliosis to the left [Figure 1b]. The pulmonary function test was suggestive of mildly restrictive disease. Airway assessment showed acceptable flexion and extension at the neck with adequate mouth opening and normal dentition, Mallampatti Class IV [Figure 1c]. The patient was accepted for surgery as American Society of Anesthesiologists Grade III; in view of odontoaxial dislocation and a normal coagulation profile, we decided to proceed with a spinal anesthetic technique under ultrasound guidance. Thorough operating room preparation was completed, including difficult airway equipment, and measures were made ready to deal with temperature fluctuations.²

The patient was positioned very carefully on the operation table, and pressure points were adequately padded. An 18-gauge intravenous (i.v.) cannula was inserted on the dorsum of the right hand. Monitors, including ECG, sphygmomanometer, and SpO₂, were placed on the patient.

Baseline blood pressure was 140/80 mmHg, heart rate was 98 beats/min, and O₂ saturation on room air was 99%. A preload of 500 ml Ringer’s lactate was administered intravenously. The patient was placed in a sitting position [Figure 1d], and using a low-frequency (2–5 MHz) curved array probe,³ a systematic ultrasound scanning protocol was used. The probe was oriented longitudinally to obtain a paramedian sagittal view of the lumbosacral spine [Figure 1e and 1f], in which the L2–L3 to L4–L5 interlaminar spaces were identified and marked by counting upward from the sacrum. The probe was then rotated 90 degrees to obtain a transverse view of the lumbar spine. The L2–L3 to L4–L5 interspinous and interlaminar spaces were identified by visualizing the intrathecal space between the ligamentum flavum–dura mater complex and the posterior aspect of the vertebral body.⁴ The midline (interspinous ligament) and the location of each interlaminar space were marked on the skin. The intersection of these two markings was used to guide a midline approach to spinal anesthesia. The depth of the posterior complex from the skin was measured as 2.4 cm. Subarachnoid block given in the L3–L4 space with a 25-gauge Quincke needle with 2.5 ml of hyperbaric bupivacaine 0.5% [Figure 1g]. There is differential attainment of sensory blockade of T-10 on the right side and T-8 on the left side. The operation lasted for 90 minutes. There was no significant variation in the vitals, and the recovery was uneventful.

Anesthetic management of OI is influenced by diversity of presentation, namely, coexisting orthopedic deformities, fragile bones prone for fractures at the time of positioning, platelet dysfunction, cardiovascular abnormalities such as mitral valve prolapse, tendency to develop malignant hyperthermia, anticipated difficult intubation because of abnormal cervical spine mobility, fragile teeth, odontoaxial dislocation, and risk of mandibular and facial fractures.

In our case, anatomic deformity was of a higher degree; even then, we preferred spinal anesthesia so as to avoid the need for tracheal intubation. Moreover, kyphoscoliosis with pectus carinatum affects vital capacity along with chest compliance, resulting in ventilation-perfusion mismatch, which eventually leads to arterial hypoxemia. Succinylcholine increases the risk of malignant hyperthermia; fasciculations can lead to fractures, and inhalational agents pose a risk for malignant hyperthermia.

Patients with distorted surface landmarks (i.e., those with clinically obvious lumbar scoliosis) have been associated with technical difficulty and block failure; therefore, preprocedural ultrasound imaging facilitates the performance of spinal anesthesia.