Unilateral Horner's Syndrome and Brachial Plexus Palsy with a Labor Epidural
Horner’s syndrome (HS) is a triad of miosis, ptosis, and anhydrosis that is often associated with enophthalmos and vasodilatation. The underlying casuse of HS vary greatly, but HS is a known complication of lumbar epidural anesthesia (Table 1). The incidence ranges from 0.5-4%1,2.
Multiple possible etiologies have been described, but cephalic spread of the local anesthetic to interrupt the sympathetic chain, in the region of C8 to as low as T4, is surmised (Image 1). The anatomical and physiologic changes associated with pregnancy may promote cephalad spread (Table 2)3.
Unilateral HS accompanied by ipsilateral brachial plexus palsy is exceedingly rare. A recent systematic review found only 18 cases of HS with altered ipsilateral arm sensory or motor function occurring after neuraxial blockade4.
A 31-year-old G1P0 at 39w6d with preeclampsia undergoing augmentation of labor requested an epidural. Past medical history included anxiety and migraines with aura. Her CBC and CMP were unremarkable.
The epidural was easily placed using loss of resistance to air and a nylon 20G closed tip catheter was threaded 4.5cm in the epidural space. After negative test dose, 10cc of 0.125% bupivacaine was given and a 0.125% bupivacaine with 2mcg/ml fentanyl infusion was started at 6 cc/hr.
Over the next 30 mins, the patient reported right hand paresthesia that progressed to right upper extremity numbness and then marked weakness. Her sensory level was found to be T10 bilaterally to temperature, without chest wall or left arm numbness, respiratory depression, or hemodynamic compromise. The patient denied headache or vision changes. Neurologic exam was notable for mild right ptosis and injected sclera, right pupil smaller than left, partial paralysis of the right upper extremity (0/5 strength in triceps, finger flexion/extension, interossei, thumb abduction, wrist flexion), decreased sensation to light touch and pinprick on the right upper extremity, and 1+ reflex in the right triceps.
The differential included preeclampsia with focal neurologic deficit, migraine with transient weakness, TIA, carotid dissection, and epidural side effect. The epidural infusion was paused for an MRI/MRA of the brain/c-spine, which was unrevealing. Soon after stopping the infusion, the patient experienced resolution of symptoms except for persistent HS. Epidural replacement was discussed with her, and she elected to continue with the original catheter. The catheter was bolused with 7cc of 0.125% bupivacaine and the infusion restarted. Within 30 mins, her pain was well controlled with a T11 bilateral sensory level, but the paresis returned to her right fingers and arm. The patient was closely observed during her 8hrs of labor, and the catheter was discontinued after delivery. Within a few hours of removal, her neurologic exam returned to baseline.
Upon our review of the literature, this is the first reported instance of HS and ipsilateral brachial plexus palsy after labor epidural placement with a symmetric, low (T10) truncal level. Prior case reports were associated with truncal levels of T6 or higher5. Additionally, prior cases often reported asymmetrical blocks, with the side affected by HS having a cutaneous block four or more dermatomal levels higher than the unaffected side4.
HS after neuraxial blockade is usually a benign phenomenon that resolves spontaneously after discontinuation of the local anesthetic.
Following onset of HS, the parturient should be assessed for hemodynamic instability, fetal well-being, dermatomal level, and coexisting neurologic deficits. While current evidence suggests it is safe to continue epidural anesthesia in the setting of isolated HS, consideration should be given to replacement of the epidural to allow for identification of persistent symptoms, which would point to a more sinister etiology.